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Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information is preliminary at time of publication and subject to change.

Recently Published Bulletin Reports

Ebeko (Russia) Ash explosions remained frequent through May 2018, with plumes typically rising more than 1 km

Langila (Papua New Guinea) Gradual decline in activity after July 2017, but continuing through May 2018

Sheveluch (Russia) Intermittent thermal anomalies along with gas and steam emissions continue through April 2018

Karangetang (Indonesia) Small ash plume and incandescence seen on 2 February 2018

Klyuchevskoy (Russia) Intermittent moderate gas, steam, and ash plumes during December 2017-February 2018

Kikai (Japan) Elevated thermal activity during February-April 2018; one earthquake swarm in March

Dieng Volcanic Complex (Indonesia) Phreatic explosion on 1 April 2018 at Sileri Crater

Ibu (Indonesia) Ongoing thermal anomalies from dome growth in the summit crater through April 2018

Bagana (Papua New Guinea) Intermittent ash plumes and thermal anomalies continue through 15 April 2018

Stromboli (Italy) Intermittent explosions and 100-m-long lava flow, November 2017-February 2018

Popocatepetl (Mexico) Ongoing steam, gas, and ash emissions along with intermittent explosions, August 2017-February 2018

Dukono (Indonesia) Ongoing ash explosions, thermal anomalies, and sulfur dioxide emissions through March 2018



Ebeko (Russia) — June 2018 Citation iconCite this Report

Ebeko

Russia

50.686°N, 156.014°E; summit elev. 1103 m

All times are local (unless otherwise noted)


Ash explosions remained frequent through May 2018, with plumes typically rising more than 1 km

The most recent eruption at Ebeko, a remote volcano in the Kuril Islands, began in October 2016 (BGVN 42:08) with explosive eruptions accompanied by ashfall. Frequent ash explosions were observed through November 2017 and the eruption remained ongoing at that time (BGVN 43:03). Activity consisting of explosive eruptions, ash plumes, and ashfalls continued during December 2017 through May 2018 (table 6). Eruptions were observed by residents in Severo-Kurilsk (about 7 km E), by volcanologists, and based on satellite imagery. The Kamchatkan Volcanic Eruption Response Team (KVERT) is responsible for monitoring Ebeko, and is the primary source of information. The Aviation Color Code (ACC) remained at Orange throughout this reporting period. This color is the second highest level of the four color scale.

Table 6. Summary of activity at Ebeko volcano from December 2017 to May 2018. Aviation Color Code (ACC) is a 4-color scale. Data courtesy of KVERT

Date Plume Altitude Plume Distance Plume Direction Other observations
1-4 and 7 Dec 2017 2 km -- -- ACC at Orange. Ashfall reported in Severo-Kurilisk. Explosions on 2-4 and 7 Dec.
8, 9, 11 Dec 2017 2.3 km -- -- Explosions.
16, 18-19, and 21-22 Dec 2017 3.5 km 16 km SSW Explosions. Ash plume and weak thermal anomaly on 16 Dec.
25 Dec 2017 1.5 km -- -- Explosion.
01-05 Jan 2018 -- -- -- No activity noted.
08-10 Jan 2018 2.5 km -- -- Explosions.
11-12, 14-16, and 18 Jan 2018 3.1 km -- -- Explosion. Minor ashfall reported in Severo-Kurilsk on 15,16, and 18 Jan.
22-23 Jan 2018 2 km -- -- Explosions.
26-27 and 29-31 Jan 2018 2.5 km -- -- Explosions. Ashfall reported in Severo-Kurilsk on 29 Jan.
05-08 Feb 2018 2.4 km -- -- Explosions. Ashfall reported in Severo-Kurilisk on 8 Feb.
09-10 and 14 Feb 2018 2.2 km -- -- Explosions.
17-18 and 20-21 Feb 2018 2.4 km -- -- Explosions. Ashfall reported in Severo-Kurilisk on 17-18 Feb.
23-25 and 27-28 Feb 2018 3.3 km -- -- Explosions.
06 Mar 2018 1.7 km -- -- Explosions.
12-13 Mar 2018 2.7 km -- -- Explosions.
18 and 21-22 Mar 2018 1.8 km -- -- Explosions. Ashfall reported in Severo-Kurilisk on 17 and 21 Mar.
23-25 and 28-29 Mar 2018 2.3 km -- -- Explosions.
31 Mar-06 Apr 2018 2.7 km -- -- Explosions.
07 and 11-12 Apr 2018 1.8 km -- -- Explosions. Ashfall reported in Severo-Kurilisk on 6 Apr.
15 and 17-19 Apr 2018 2.6 km -- -- Explosions.
21 and 25 Apr 2018 2.5 km -- -- Explosions.
01-03 May 2018 2.8 km -- -- Explosions.
04 and 06-10 May 2018 2.4 km -- -- Explosions.
12-14 May 2018 2.8 km 21 km SW Explosions. Ash plume drifted SW on 13 May.

Minor ash explosions were reported throughout the period from December 2017 through May 2018 (figure 17). Minor amounts of ash fell in Severo-Kurilisk at the end of 2017 and into 2018. Ash was reported on 2-4, and 7 December 2017; 15, 16, 18, and 29 January 2018; 8, 17, and18 February; 17 and 21 March; and 6 April. Ash plume altitudes during this reporting period ranged from 1.5 to 3.5 km (table 6); the summit is at 1.1 km.

Figure (see Caption) Figure 17. Explosions from Ebeko sent ash up to an altitude of 1.5 km, or about 400 m above the summit, on 6 February 2018. Courtesy of T. Kotenko (IVS FEB RAS).

Geologic Background. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/).


Langila (Papua New Guinea) — June 2018 Citation iconCite this Report

Langila

Papua New Guinea

5.525°S, 148.42°E; summit elev. 1330 m

All times are local (unless otherwise noted)


Gradual decline in activity after July 2017, but continuing through May 2018

Langila, one of the most active volcanoes of New Britain (figure 7), has been intermittently ejecting ash since April 2016 (BGVN 42:09). Volcanic ash warnings continue to be issued by the Darwin Volcanic Ash Advisory Centre (VAAC). Recent ash plume altitudes (table 5) are in the range of 1.5-2.5 km, but several in mid-April to mid-May 2018 reached up to twice that level. Thermal anomaly data acquired by satellite-based MODIS instruments showed a gradual decrease in power level and occurrence through mid- to late-2017, followed by significantly fewer alerts and anomalies in the first half of 2018. Rabaul Volcano Observatory (RVO) data indicates the activity during 2017 was primarily located in Crater 2 (northern-most crater).

Figure (see Caption) Figure 7. Satellite imagery showing Langila volcano at the far NW end of New Britain island. The brown color of recent lava flows and other volcanic deposits are easily noticeable compared to green vegetated areas. The volcano is about 9 km due south of the community labeled Poini. Imagery in this view is from sources listed on the image; courtesy of Google Earth.

Table 5. Reported data by Darwin Volcanic Ash Advisory Centre (VAAC) on ash plume altitude and drift from Langila based on analyses of satellite imagery and wind model data between 21 June 2017 and 28 May 2018.

Dates Ash Plume Altitude (km) Ash Plume Drift Other Observations
07 Aug 2017 2.1 55 km NW --
09 Aug 2017 1.8 N --
16 Aug 2017 2.1 NW --
01-02 Sep 2017 1.8 N, NW --
07-08, 10-12 Sep 2017 1.8-2.4 NNW, NW, SW --
22-23 Sep 2017 2.1 NNW --
04 Oct 2017 1.8 N Minor ash emission
11, 15-16 Oct 2017 1.8-2.1 NE, NNW, NW --
17-18, 20 Oct 2017 1.5-1.8 NE, NNW, NW --
05 Nov 2017 3.7 SE, ESE --
15-16 Nov 2017 1.8-2.7 S, SW --
15 Apr 2018 3.7 S --
24 Apr 2018 4 SW Ash dissipated in 6 hours
13 May 2018 5.5 W At 0709; ash dissipated in 6 hours
17-18, 21-22 May 2018 2.1-2.4 WSW, W, WNW --
23, 26-28 May 2018 2.4-3 WSW, W, NW --

MIROVA analysis of thermal anomalies measured by MODIS satellite sensors show a gradual decline of radiative power from early June 2017 to the end of the year (figure 8). Sporadic low-power anomalies occurred in January, April, and May 2018.

Figure (see Caption) Figure 8. Thermal anomalies from MODIS data analyzed by MIROVA, plotted as log radiative power vs time for the year ending 6 June 2018. Courtesy of MIROVA.

Thermal alerts from MODVOLC analyses were concentrated between early June 2017 and late September 2017 (figure 9), with only one pixel being measured in 2018 through early June, that alert being on 5 January 2018.

Figure (see Caption) Figure 9. Map showing thermal anomalies from MODIS data analyzed by MODVOLC for the year ending 6 June 2018. Courtesy of HIGP - MODVOLC Thermal Alerts System.

Geologic Background. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea.


Sheveluch (Russia) — May 2018 Citation iconCite this Report

Sheveluch

Russia

56.653°N, 161.36°E; summit elev. 3283 m

All times are local (unless otherwise noted)


Intermittent thermal anomalies along with gas and steam emissions continue through April 2018

An eruption at Sheveluch has been ongoing since 1999, and volcanic activity was previously described through January 2018 (BGVN 43:02). Ongoing activity has consisted of pyroclastic flows, explosions, and lava dome growth with a viscous lava flow in the N. According to the Kamchatka Volcanic Eruption Response Team (KVERT), moderate emissions of gas-and-steam have continued, and ash explosions up to 10-15 km in altitude could occur at any time. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) throughout this reporting period from February through April 2018.

KVERT reported continuous moderate gas-and-steam plumes from Sheveluch during February-April 2018 (figure 49). Satellite imagery interpreted by KVERT showed a thermal anomaly over the volcano on 13 days during February, 21 days in March, and 15 days in April. Cloud cover obscured satellite imagery the remainder of the time during this reporting period.

Figure (see Caption) Figure 49. Photo of the lava dome at Sheveluch on 25 March 2018. Courtesy of Yu. Demyanchuk (IVS FEB RAS, KVERT).

The MIROVA system detected intermittent low-power thermal anomalies from February through April 2018. Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were not detected during this period.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Karangetang (Indonesia) — May 2018 Citation iconCite this Report

Karangetang

Indonesia

2.781°N, 125.407°E; summit elev. 1797 m

All times are local (unless otherwise noted)


Small ash plume and incandescence seen on 2 February 2018

Eruptive activity at Karangetang between June 2014 and March 2016 included intermittent ash plumes, lava flows, pyroclastic flows, and persistent thermal anomalies from a slowly growing lava dome (BGVN 42:02) south of the highest summit (figure 16). Activity since mid-March 2016 has been low, with only a few notable events consisting of a possible ash plume on 10 May 2017, a strong sulfur dioxide emission on 10 October 2017, and a small ash explosion on 2 February 2018. Information was mainly provided by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), the Darwin Volcanic Ash Advisory Centre (VAAC).

Figure (see Caption) Figure 16. Satellite image of the summit area of Karangetang on 27 June 2012. The active dome is steaming, with the fumarolic plume curving towards the NE. Dark-colored recent lava flows are noticeable. The higher inactive summit is about 500 m N and 20 m higher than the active dome. Courtesy of DigitalGlobe and Google Earth.

Based on analyses of satellite imagery, wind data, and ground-based visual observations, the Darwin VAAC reported that on 10 May 2017 a gas-and-steam plume apparently containing ash rose to an altitude of 3.6 km and drifted over 35 km SE. The Aviation Color Code was briefly raised to Orange.

According to a news account (Antara News) that quoted the chief of the volcano's observatory post, "sulfuric smoke" rose 200 m on 10 October 2017. The official stated that this was natural activity for the volcano and also indicated that several types of tremor had occurred the previous day. A small SO2 anomaly near the volcano was detected on 11 October 2017, registering 2.1 Dobson Units on the Aura satellite Ozone Monitoring Instrument.

In a Volcano Observatory Notice for Aviation (VONA) issued on 2 February 2018, PVMBG reported an explosion, crater incandescence, and an ash plume that rose 600 m above the summit. The Aviation Color Code was raised from Unassigned to Yellow.

No MODVOLC thermal anomalies were detected during the reporting period. The MIROVA system, however, detected twelve scattered low-power thermal anomalies in the year ending on 26 April 2018. One of the thermal anomalies occurred around 10 October.

Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Antara News (URL: https://en.antaranews.com/).


Klyuchevskoy (Russia) — May 2018 Citation iconCite this Report

Klyuchevskoy

Russia

56.056°N, 160.642°E; summit elev. 4754 m

All times are local (unless otherwise noted)


Intermittent moderate gas, steam, and ash plumes during December 2017-February 2018

Klyuchevskoy has been active for many decades, alternating between eruptive and less active periods. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters. The current eruptive period began in late August 2015. Lava effusion ended in early November 2016 but explosive activity continued to be observed through October 2017 (BGVN 42:11) and into mid-February 2018 as described below. The Kamchatkan Volcanic Eruption Response Team (KVERT) is responsible for monitoring, and is the primary source of information. The Aviation Color Code remained at Orange through April 2018.

Strong gas-and-steam activity was observed on 2-5 December 2017. Ash plumes rose to an altitude of 5.5 km and extended for about 180 km (figure 26). Emissions were reported at 2300 on 5 December 2017 with plumes extending 170 km E. Gas-and-steam and ash plumes extended for approximately 95 km to the E and SW on 7 and 13 December, respectively. On 16-19 December the gas-steam and ash plumes extended approximately 140 km E, and on 22-25 December they reached about 220 km E.

Figure (see Caption) Figure 26. Photo of Klyuchevskoy showing a gas-and-steam plume on 3 December 2017. Courtesy of Yu. Demyanchuk (IVS FEB RAS, KVERT).

Moderate eruptive activity continued into January and February 2018. On 1, 3, and 4 January gas-and-steam plumes with ash extended approximately 150 km downwind. The plume extended to 160 km N, W, and E on 5, 6, and 8-10 January (figures 27 and 28). On 12 and 17-18 January, the plume extended to 120 km W and E. The Tokyo VAAC reported that on 18 February an ash plume rose to an altitude of 5.2 km and extended SW. No further reports of ash plumes were reported through April 2018.

Figure (see Caption) Figure 27. Gas-and-steam plume with minor ash content rising from Klyuchevskoy on 6 January 2018. Courtesy of Yu. Demyanchuk (IVS FEB RAS, KVERT).
Figure (see Caption) Figure 28. Close-up satellite image of a small plume of gas, steam, and ash rising from Klyuchevskoy on 10 January 2018 taken by the Operational Land Imager (OLI) on Landsat 8. Courtesy of NASA Earth Observatory, with imagery by Joshua Stevens and Jeff Schmaltz, using Landsat data from the U.S. Geological Survey.

A weak thermal anomaly was detected over the volcano on 5, 6, 11, 16, and 22, December 2017; and on 3, 6, 8, 11, 12, 15 and 17 January 2018. The number of MIROVA thermal anomalies detected also increased in the first half of January 2018; most were low to slightly moderate in intensity.

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Institute of Volcanology and Seismology, Far Eastern Branch, Russian Academy of Sciences (IVS FEB RAS), 9 Piip Blvd., Petropavlovsk-Kamchatsky 683006, Russia (URL: http://www.kscnet.ru/ivs/eng/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Earth Observatory, EOS Project Science Office, NASA Goddard Space Flight Center, Goddard, Maryland, USA (URL: http://earthobservatory.nasa.gov/); Tokyo Volcanic Ash Advisory Center (VAAC), 1-3-4 Otemachi, Chiyoda-ku, Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).


Kikai (Japan) — May 2018 Citation iconCite this Report

Kikai

Japan

30.793°N, 130.305°E; summit elev. 704 m

All times are local (unless otherwise noted)


Elevated thermal activity during February-April 2018; one earthquake swarm in March

Heightened activity at Kikai (also known as Satsuma Iwojima) was reported during January 2013-July 2014 (BGVN 3907), which included one eruption with intermittent explosions, occasional ash and steam plumes, and sporadic weak seismic tremor. Subsequently, seismicity remained at background levels, and plume activity was low. A short-lived period of heightened activity occurred in March 2018, with increased daily plume heights, sulfur dioxide output, and seismicity. Activity returned to background levels by 26 April. This report is based on information supplied by the Japanese Meteorological Agency (JMA).

JMA reported that one small-amplitude short-duration volcanic tremor was detected on 16 March 2018. The number of volcanic earthquakes increased on 19 March, with 93 occurrences, prompting JMA to raise the Alert Level from 1 (active volcano) to 2 (restricted area around the crater), on a 5-level scale. The report noted increased thermal activity since February, with occasional visual observations of incandescence. Plume heights and volcanic earthquakes briefly increased during 22-23 March (figure 8, plot 4).

Figure (see Caption) Figure 8. Plots showing multi-year records of measured plume heights (1 and 4) and volcanic earthquakes (2 and 5) during January 1998-April 2018 from Kikai. Explosive events are indicated by the small volcano icons along the top of plot 1. Plot 3 indicates measured sulfur dioxide in tons/day since 2012. The orange diamonds on plot 4 indicate observations of incandescence. Plume heights are measured in meters above the crater. This record is from a seismic station located less than 1 km from the summit. Courtesy of Japan Meteorological Agency (JMA).

The number of volcanic earthquakes was low during 27 March-2 April. A white plume at the Iwo-dake summit crater rose to 1,800 m above the crater rim in late March (figure 8, plot 4), the highest seen in many years. At the same crater a highly sensitive surveillance camera revealed incandescence at night on 27 and 28 March due to increased thermal activity. No incandescence was observed after 12 April (figure 8, plot 4).

In its report for 20-26 April, JMA noted a white plume at the Iwo-dake summit crater that rose to 700 m above the rim. A field survey conducted on 25 and 26 April confirmed the slight expansion of a thermal anomaly area when compared to 24 and 25 March, but the release amount of sulfur dioxide was slightly less than 300 tons per day (compared with 600 tons on March 24) (figure 8, plot 3).

On 27 April 2018, with volcanic earthquakes being small in number and no observed volcanic tremor, JMA determined that activity had decreased and reduced the warning level from 2 to 1.

Geologic Background. Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. Kikai was the source of one of the world's largest Holocene eruptions about 6300 years ago. Rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred in the 20th century at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km east of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).


Dieng Volcanic Complex (Indonesia) — May 2018 Citation iconCite this Report

Dieng Volcanic Complex

Indonesia

7.2°S, 109.879°E; summit elev. 2565 m

All times are local (unless otherwise noted)


Phreatic explosion on 1 April 2018 at Sileri Crater

Dieng has had a history of intermittent phreatic explosions. In 2017, explosions occurred on 30 April, 24 May, and 2 July (BGVN 42:10). Another phreatic explosion occurred on 1 April 2018. The volcano is monitored by the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Centre for Volcanology and Geological Hazard Mitigation or CVGHM).

PVMBG reported that a phreatic explosion at the Sileri Crater lake (Dieng Volcanic Complex) occurred at 1342 on 1 April 2018, ejecting mud and material 150 m high, and up to 200 m in multiple directions. The event was preceded by black emissions that rose 90 m, and then diffuse white emissions that rose 150 m. The report noted that few tourists were in the area due to rainy weather; visitors are not permitted within 200 m of the crater rim.

According to a news report (The Jakarta Post) that cited an official of the National Disaster Management Agency (BNPB), no toxic gases such as carbon dioxide, hydrogen sulfide, or sulfur dioxide were detected in the explosion.

Geologic Background. The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century CE. The Dieng volcanic complex consists of two or more stratovolcanoes and more than 20 small craters and cones of Pleistocene-to-Holocene age over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of dissected to youthful cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but have not occurred in historical time, when activity has been restricted to minor phreatic eruptions. Toxic gas emissions are a hazard at several craters and have caused fatalities. The abundant thermal features and high heat flow make Dieng a major geothermal prospect.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/); The Jakara Post (URL: http://www.thejakartapost.com).


Ibu (Indonesia) — May 2018 Citation iconCite this Report

Ibu

Indonesia

1.488°N, 127.63°E; summit elev. 1325 m

All times are local (unless otherwise noted)


Ongoing thermal anomalies from dome growth in the summit crater through April 2018

Ongoing activity at Ibu volcano from April through August 2017 consisted primarily of intermittent ash explosions (BGVN 42:10). Based on data and reports through April 2018, the eruption that began on 5 April 2008 appeared to be continuing. Monitoring of the volcano is the responsibility of the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Center for Volcanology and Geological Hazard Mitigation (CVGHM). Additional data below come from the Darwin Volcanic Ash Advisory Centre (VAAC) notices, with infrared MODIS data analyzed by the MODVOLC and MIROVA systems.

There were no reports of ash plumes from September 2017 through early March 2018. Although the summit area is often covered in fog, on 7-8 March ash plumes were observed rising 300-600 m above the crater rim and drifting W and S (table 3). Additional eruption plumes with ash were reported on 20 and 30 April. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay at least 2-3.5 km away from the active crater.

Table 3. Monthly summary of reported ash plumes and MODIS thermal anomalies from Ibu for August 2017-April 2018. The direction of drift for the ash plume through each month is highly variable. Data from Darwin VAAC, PVMBG, and MODVOLC.

Month Plume Altitude (km) Plume Drift Days with MODVOLC Alert Pixels
Sep 2017 -- -- 4
Oct 2017 -- -- 5
Nov 2017 -- -- 4
Dec 2017 -- -- 4
Jan 2018 -- -- 4
Feb 2018 -- -- 2
Mar 2018 1.6-1.9 W, S 2
Apr 2018 1.8-1.9 E, S 3

Thermal anomalies identified by the MIROVA system using MODIS satellite data (figure 12) show that activity has been ongoing and almost continuous during May 2017-April 2018. Anomalies for the same time period detected and mapped using MODVOLC (figure 13, table 3) appear to be centered towards the north part of the crater and possibly extending down the N flank. This may indicate eruptive activity similar to that reported by PVMBG in June-December 2013 (BGVN 38:11) where the lava dome grew above the crater rim and sent incandescent material over a low notch in the rim and down a river valley towards Duono village, about 5 km NW.

Figure (see Caption) Figure 12. Thermal anomalies at Ibu shown on a MIROVA plot (Log Radiative Power) for the year ending 3 May 2018. Courtesy of MIROVA.
Figure (see Caption) Figure 13. A contour map showing MODVOLC thermal alert pixels at Ibu for the year ending 3 May 2018. Pixels are centered at the north crater rim and down the N flank. Courtesy of Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System.

Geologic Background. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).


Bagana (Papua New Guinea) — May 2018 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Intermittent ash plumes and thermal anomalies continue through 15 April 2018

Bagana is a relatively remote volcano on Bougainville Island that is poorly monitored except by satellite. The most recent eruptive phase began on or before early 2000 with intermittent ash plumes and thermal anomalies (BGVN 41:04, 41:07, 42:08). During the period 13 June 2017-15 April 2018, this same pattern of activity continued. Intermittent ash plumes rose to 2.1-2.4 km altitude (table 3). Plume activity was especially elevated during August 2017. Satellite data indicate that both plume activity and thermal alerts had decreased markedly by the beginning of March 2018.

Table 3. Summary of ash plumes from Bagana reported during 14 June 2017-15 April 2018. Courtesy of the Darwin Volcanic Ash Advisory Centre (VAAC).

Date Max Plume Altitude (km) Plume Drift
14 Jun 2017 2.1 65 km SW, W, NW
22, 25 Jun 2017 2.1 NW
02 Jul 2017 2.1 W
16 Jul 2017 2.1 W
23 Jul 2017 2.1 W
01 Aug 2017 2.1 W
05-08 Aug 2017 2.1 Multiple
09-10, 13 Aug 2017 2.4 W, NW (120 km W on 13 Aug)
24-28 Aug 2017 2.1-2.4 WNW, W, SW
31 Aug 2017 2.1 N, W, SW
11-12 Sep 2017 2.1 NW
27 Oct 2017 2.1 E, NE
03 Nov 2017 2.4 NE
15-17 Nov 2017 2.1 N, SW, SSW, W
25-26 Dec 2017 2.4 NE
07-08 Feb 2018 2.4 NE
26-27 Feb 2018 2.1 WNW
02 Mar 2018 2.4 NE
14-15 Apr 2018 2.1-2.4 110 km SW

Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were observed 0-3 days each month during June-November 2017, seven days in December 2017, one day in January 2018, and two days in February 2018. More than two pixels were recorded on 4-5 and 9 December (up to five pixels), 31 January (4 pixels), and 4 February (5 pixels).

The MIROVA (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, recorded a moderate number of thermal alerts within 5 km of the volcano from June through late November 2017, except for a decrease between mid-September and mid-October (figure 29). Activity rose sharply during the end of November through early December and again during the first half of January before tapering off, a pattern inconsistent with the reported ash plumes. Few hotspots were detected between mid-February through 15 April, a pattern consistent with the MODVOLC data.

Figure (see Caption) Figure 29. Thermal anomalies at Bagana shown on a MIROVA plot (Log Radiative Power) for the year ending 27 April 2018. Courtesy of MIROVA.

Sulfur dioxide anomalies since June 2016 above 2.5 Dobson Units (Ozone Monitoring Instrument, OMI) or above 1.6 Dobson Units (Ozone Mapping and Profiler Suite, OMPS) occurred in 2016 on 4 and 6 July, 10-11 October, 11 November, and 3 December. Similar emissions were detected in 2017 on 30 January, 3 and 19 March, 15 April, 5 August, and 2 and 7 December. The satellite data showed high levels of SO2 in 2018 on 8 and 24 February, and 29 March.

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA, a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).


Stromboli (Italy) — April 2018 Citation iconCite this Report

Stromboli

Italy

38.789°N, 15.213°E; summit elev. 924 m

All times are local (unless otherwise noted)


Intermittent explosions and 100-m-long lava flow, November 2017-February 2018

Confirmed historical eruptions at Stromboli go back 2,000 years; this island volcano in the Tyrrhenian Sea has been a natural beacon with its near-constant fountains of lava for eons. Eruptive activity at the summit consistently occurs from multiple vents at both a north crater area (N Area) and a southern crater group (S or CS Area) on the Terrazza Craterica at the head of the Sciara del Fuoco, a large scarp that runs from the summit down the NW side of the island. Thermal and visual cameras that monitor activity at the vents are located on the nearby Pizzo Sopra La Fossa, above the Terrazza Craterica, and at a location closer to the summit craters.

Eruptive activity during January-October 2017 peaked during June and then declined through August, returning to background levels in September; it included intermittent periods of frequent explosions from both crater areas that sent ash, lapilli, and bombs across the Terrazza Craterica and onto the head of the Sciara del Fuoco (BGVN 43:02). This report covers similar activity from November 2017-February 2018. Weekly reports of activity were provided by Italy's Instituto Nazionale de Geofisica e Vulcanologia (INGV), Sezione de Catania, which monitors the gas geochemistry, deformation, and seismicity, as well as surficial activity.

An explosive sequence on 1 November 2017 followed less than two weeks after a similar event on 23 October (BGVN 43:02) in the CS Area, creating Strombolian activity that sent ejecta 300 m high. Intermittent explosions and spattering continued until the next large explosion on 1 December, also in the CS Area. A general increase in seismicity was recorded during December 2017; intense spattering in the N Area on 15 December formed a lava flow that traveled 100 m N from the rim of the vent before stopping. The number of explosive events remained high (more than 20 per hour) through December, when both the intensity and rate of activity declined significantly, reaching levels below 10 events per hour in early February, and remaining there for the rest of the month. The general levels of intensity in the N and CS Areas, apart from the larger explosive events, were variable throughout November 2017-February 2018, generally increasing during December and decreasing during January (table 3). This pattern of activity is also reflected in the variation of the thermal activity that was recorded in the MIROVA thermal data during that time (figure 117), and the MODVOLC thermal alert data which recorded two alerts in November, and 14 in December, but none after that through February 2018.

Table 3. General intensity and activity levels at the summit vents in the N Area and CS Area at Stromboli, November 2017-February 2018. Intensity values correspond to the height of the ejecta above the vent: Low = less than 80 m high, Med-Low = less than 120 m High, Medium = less than 150 m high, Med-High = sometimes to 200 m, High = over 200 m. Coarse ejecta consisted of lapilli and bombs, and fine ejecta was primarily ash and smaller lava fragments.

Month N Area Activity N Area Intensity N Area Explosions/Hour CS Area Activity CS Area Intensity CS Area Explosions/Hour
Nov 2017 Explosions with lapilli and bombs at both vents N1 and N2, occasional vertical lava jets at N1 Mostly Low to Med-Low, Medium during last week 5-12 Continuous degassing, explosions with lapilli and bombs, and intense spattering episodes at C, explosions with lapilli and bombs and vertical lava jets at S2, S1 only active during 1 Nov explosion Low and Med-Low 1-7
Dec 2017 Explosions with lapilli and bombs at both N1 and N2, mixed with ash at N1 during last week; intense spattering mid-month (lava flow) Variable, Low to High 5-18 Continuous degassing interrupted by intense spattering and explosions at C, weakened by month's end; No activity at S1, explosions at S2 of lapilli and bombs mixed with meter-size fragments of lava during first half of month; predominantly fine ash mixed with coarse material during second half of month Med-Low at C; variable Low to High at S2 2-15
Jan 2018 Explosions at N1 and N2; more lapilli and bombs during first half of month, mostly ash mixed with coarser material during second half of month Variable, Mostly Low to Medium, occasional High 3-21 Continuous degassing activity interrupted sporadically by explosions of coarse material at C; No activity at S1 until incandescence and occasional ash during last week; explosions at S2 of predominantly fine ash occasionally mixed with coarse lapilli and bombs Variable, Low to Med-High 1-10
Feb 2018 Explosions of mostly coarse material (lapilli and bombs) sometimes mixed with ash from N1. More fine ash, less coarse material from N2. Med-Low at N1, Low at N2 2-9 Continuous degassing at C, two points of incandescence after mid-month; occasional incandescence and modest ash emissions at S1 during first half of month; Explosions of predominantly fine ash at S2 Low 1-5
Figure (see Caption) Figure 117. MIROVA thermal data for Stromboli for the year ending on 2 May 2018 showed a gradual increase in thermal energy during mid-November 2017, peaking in mid-December, and then decreasing rapidly in early January to low levels by the end of the month that persisted through February 2018. Courtesy of MIROVA.

On 1 November 2017 at 0829 UTC a strong explosive sequence that lasted about 2 minutes was observed in the CS Area of the Terrazza Craterica (figure 118). The first explosion sent bombs and lapilli around the slopes of the terrace and the ejecta exceeded 300 m in height. Two more explosions followed soon after, sending material about 150 m into the air.

Figure (see Caption) Figure 118. The explosive sequence of 1 November 2017 at Stromboli, taken from the INGV thermal and visual cameras at the 400 m level sent ash, bombs, and lapilli as high as 300 m. The time period covered by the explosions is about two minutes. Courtesy of INGV (Report 45/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 07/11/2017).

A survey by INGV scientists during 3-5 November 2017 evaluated the effects of this and the previous explosion on 23 October on the Terrazza Craterica. They noted that a large depression with a vent at the base, formed in the CS Area after the 23 October explosions, had been significantly enlarged during the 1 November explosions. Continuous spattering and strong incandescence were observed during the survey at the 4-m-wide C vent. They also observed that the explosive activity at S2 was produced by three emission points. They noted that the N1 site consisted of a single hornito and a secondary vent on the side flank (figure 119).

Figure (see Caption) Figure 119. Several changes to the Terrazza Craterica at Stromboli were visible after the two strong explosive sequences of 23 October and 1 November 2017. a) The Terrazza Craterica on 5 November 2017; b) vent C on 30 September 2017 and c) on 5 November 2017 after the two major explosions; d) vent N1 on 30 September and e) on 5 November 2017. Photograph by D. Andronicus, courtesy if INGV (Report 45/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 07/11/2017).

The 23 October 2017 explosions ejected light brown scoriaceous material S and SE, almost reaching the Pizzo Sopra La Fossa 300 m to the E. A wide band of lithic blocks was also observed on the N flank of the W part of the Valle della Luna, an open area located S of the Terrazza, over a ridge at a higher elevation. During the 1 November explosions abundant black scoriaceous material formed spatter that covered the entire Terrazza Craterica and reached the W wall of the Pizzo facing the craters. Some of this material additionally landed on the NW ridge of the Valle della Luna and on its N flank. Blocks as large as 2 m were ejected during the 1 November event, along with reddish debris that dispersed in a wide area of the Terrazza Craterica and onto the SE flank at the S end of the Pizzo.

Vent C exhibited continuous degassing activity interrupted by short spattering episodes observed mainly on 15 and 21 November 2017. During 20-24 November, a new vent opened between vents S2 and C, which was sporadically active with incandescence and small explosions of fine-grained material. Three emission points were active from the C vent area at the end of November (figure 120).

Figure (see Caption) Figure 120. The two crater areas on the Terrazza Craterica at Stromboli are visible from the thermal camera on the Pizzo Sopra La Fossa, seen here on 27 November 2017. The abbreviations and arrows indicate the names and locations of the active vents. Three emission points were active at vent C at the end of November 2017. Courtesy of INGV (Report 48/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 28/11/2017).

On 1 December 2017 at 1242 UTC a strong new explosive sequence in the CS crater area was recorded by the seismic network, although weather conditions permitted only observations of incandescence during the event. A large crater was noted a few days later in the area where the three emission points had been active at vent C. A general increase in seismic activity was observed beginning on 4 December that included increases in tremor amplitude, frequency and amplitude of VLP quakes, and the amplitude of explosion earthquakes. On 9 December, numerous explosions from vent S2 combined with strong winds and sent debris as far as the Pizzo Sopra La Fossa located 300 m E (figure 121).

Figure (see Caption) Figure 121. The infrared camera on the Pizzo Sopra La Fossa captured an explosion produced by vent S2 in the CS Area at Stromboli on 9 December 2017; ejecta reached the Pizzo area. Courtesy of INGV (Report 50/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 12/12/2017).

The general increase in seismicity continued into the second week of December 2017. On 15 December 2017 intense spattering began at vent N1 at 1019 UTC. At 1330 the lava overflowed the crater rim and flowed N towards the Pianoro area, the N facing slope of the Terrazza Craterica, reaching about 100 m from the rim of N1 before stopping by 1530 that afternoon (figure 122).

Figure (see Caption) Figure 122. Images taken by the infrared camera at the 400 m level of the lava overflow on 15 December 2017 from the N1 vent at Stromboli. Courtesy of INGV (Report 51/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 19/12/2017).

A survey by INGV scientists on 15 December 2017 revealed that the biggest change caused by the 1 December explosion was the formation of a new cone at vent S2 (figure 123a) with an inner crater that was almost 40 m wide. Emissions of dark ash 2-3 times per hour were observed along with spattering and ejected blocks of lava. Vent C, which had been a small pit crater prior to the explosion (figure 123b), had become a small cone that was degassing from the crater, with two smaller lateral vents exhibiting weak but continuous spattering activity (figure 123c). Vent N2 was characterized by infrequent Strombolian activity (1-2 explosions per hour). Most of the activity on 15 December was at vent N1 (figure 123a, e), where INGV scientists observed a new vent with continuous and increasing spattering that soon formed a lava flow. The flow traveled quickly across the crater area. Between 1300 and 1420, 3-4 violent and prolonged explosions at N1 ejected lava fragments tens of meters from at least four emission points. The area was covered with abundant scoriaceous material with average dimensions of 5-6 cm, and numerous fragments of black scoriaceous spatter ranging in size from 20 to 40 cm long; a few were as large as 100 cm.

Figure (see Caption) Figure 123. INGV scientists recorded the changes at Stromboli's summit on 15 December 2017 that resulted from the explosions of 1 December, as well as events that day that generated a short lava flow. a) the Terrazza Craterica on 15 December 2017; b) vent C on 5 November and c) on 15 December after the explosions of 1 December created a cone; d) vent N1 on 5 November and e) on 15 December; the lava flows were produced by vents N1a and N1d. Photo by D. Andronicus, courtesy if INGV (Report 51/2017, Bollettino settimanale sul monitoraggio vulcanico, geochimico, delle deformazioni del suolo e sismico del vulcano Stromboli del 19/12/2017.

Activity diminished during January 2018; low- to medium-intensity explosions were typical in the N Area and degassing continued with intermittent explosive activity at the CS Area. During February 2018 activity decreased further with the overall explosion rate averaging generally less than 10 events per hour, a significant decline after the increases in activity that began in early November 2017 (figure 124).

Figure (see Caption) Figure 124. The hourly frequency of the explosive events at Stromboli as recorded by the surveillance cameras from 1 July 2017-5 March 2018, averaged by day. The information is grouped by explosions at the N Area and the CS Area, and also shown as the total average. The Total value is the sum of the average hourly frequency by day of all the explosive events produced by the active vents. Courtesy of INGV (Repprt 10/2018, Stromboli, Bollettino Settimanale, 26/02/2018 - 04/03/2018, issue date 06/03/2018).

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period from about 13,000 to 5000 years ago was followed by formation of the modern edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania, Piazza Roma 2, 95123 Catania, Italy, (URL: http://www.ct.ingv.it/en/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).


Popocatepetl (Mexico) — April 2018 Citation iconCite this Report

Popocatepetl

Mexico

19.023°N, 98.622°W; summit elev. 5393 m

All times are local (unless otherwise noted)


Ongoing steam, gas, and ash emissions along with intermittent explosions, August 2017-February 2018

Located 60 km SE of Mexico City, frequent historical eruptions have been reported from Popocatépetl going back to the 14th century. Activity increased in the mid-1990s after about 50 years of quiescence, and the current eruption, which has been ongoing since January 2005, has included frequent ash plumes and numerous episodes of lava-dome growth and destruction within the 500-m-wide summit caldera. Multiple emissions of steam and gas occur daily, rising generally 1-4 km above the 5.4-km-elevation summit; many contain small amounts of ash. Larger, more explosive events that generate ashfall in neighboring communities often occur every week.

Activity through July 2017 was typical of the ongoing eruption with near-constant emissions of water vapor, gas, and minor ash, as well as multiple explosions every week with ash-plumes and incandescent blocks sent down the flanks (BGVN 42:09). This report covers similar activity through February 2018. Information about Popocatépetl comes from daily reports provided by México's Centro Nacional de Prevención de Desastres (CENAPRED); ash emissions are also reported by the Washington Volcanic Ash Advisory Center (VAAC). Satellite visible and thermal imagery and SO2 data also provide important observations.

Near-constant emissions of steam and gas, often with minor ash content, were typical activity for throughout August 2017-February 2018. Intermittent larger explosions with plumes of moderate ash content that generated ashfall in nearby communities were reported in most months, including several times during October and November 2017, reaching communities as far as 70 km away. Incandescence at the summit was often observed on clear nights, and Strombolian activity that sent incandescent blocks several hundred meters down the flanks occurred at least once each month during September 2017-January 2018. The tallest ash plumes during the period reached 9.1 km altitude in mid-October and 10.3 km altitude at the end of January 2018. Thermal anomalies were persistently detected in satellite data throughout the period, and SO2 plumes were recorded every month with satellite instruments.

Activity during August-September 2017. The Washington VAAC reported satellite observations of an ash plume extending 55 km W of the summit at 6.4 km altitude on 31 July 2017; the plume was mostly gas and steam with a small amount of ash. CENAPRED reported ashfall in Ozumba (18 km W) on 1 August from a plume that rose 2 km above the summit. They also noted numerous low-intensity explosions with steam, gas, and ash during 5-7 August. A small explosion early on 14 August produced a 500-m-high plume with minor ash content that drifted SW. Two explosions later in the day generated ash plumes that rose 0.8 and 1.5 km from the summit and drifted W (figure 94). Another explosion on 15 August produced a plume over 1 km in height with moderate ash content. On 21 August CENAPRED reported an ash plume that rose 4 km and drifted NW (figure 95). The Washington VAAC reported this plume extending 33 km W from the summit at 7.6 km altitude. Later in the day the ash cloud was observed about 230 km W of the summit, and a new cloud at a slightly lower altitude had drifted 45 km NW.

Figure (see Caption) Figure 94. An ash plume drifted W from Popocatépetl on 14 August 2017 as seen from the Tlamacas webcam located about 5 km N of the volcano. Courtesy of CENAPRED.
Figure (see Caption) Figure 95. An ash plume at Popocatépetl rose 4 km above the summit on 21 August 2017 and drifted over 200 km W before dissipating. View is from the Altzomoni webcam, located about 10 km N of the summit. Courtesy of CENAPRED.

CENAPRED noted 22 explosions with ash during 25-26 August that drifted N and NW. They were observed in satellite imagery by the Washington VAAC at 7.6 km altitude. Eleven explosions with small amounts of ash were reported by CENAPRED on 27 August. There were daily explosions during 28-31 August, but weather clouds obscured views of the summit. Incandescence at the summit crater was observed on many clear nights during August.

During 1-11 September 2017 cloudy conditions generally prohibited observations of the summit, but low-intensity emissions of steam and gas were briefly observed, many containing minor ash. Five explosions with minor ash emissions were reported by CENAPRED on 12 September; the Washington VAAC noted the ash plume in satellite imagery at 6.7 km altitude drifting slowly N. CENAPRED reported 22 explosions with ash and incandescent rocks on the NE flank during 12-13 September.

The Washington VAAC reported ash plumes on 13 September at 8.2 km altitude, on 18 September at 6.4 km altitude drifting W, and on 23 September near 7 km altitude moving to the NNE. Numerous explosions were reported by CENAPRED during 27 and 28 September (figure 96). The Washington VAAC reported the dense ash plume from these explosions at 6.7 km altitude drifting WSW. It extended 130 km W of the volcano by early afternoon on 27 September. CENAPRED reported that an explosion late on 30 September sent incandescent fragments 0.8 km from the crater and produced a dense ash column that rose more than 2 km above the summit.

Figure (see Caption) Figure 96. A dense ash emission from Popocatépetl on 27 September 2017 extended 130 km W before dissipating as viewed from the Altzomoni webcam, located about 10 km N of the summit. Courtesy of CENAPRED.

Activity during October-November 2017. The ash plume from the explosion late on 30 September 2017 was visible in satellite imagery the following morning located 15 km SW from the summit at 7.9 km altitude according to the Washington VAAC. CENAPRED reported three explosions on 2 October and five explosions the next day, causing ashfall in Atlautla (17 km W), Tepetlixpa (21 km W), and Ozumba. Three explosions on 5 October resulted in ashfall in Totolapan (32 km W), Tlalnepantla (40 km W), and Cuernavaca (64 km W), and closer to the volcano in Ecatzingo (15 km SW), Atlautla, and Tepetlixpa. Lahars were also observed on the W flank, but there were no reports of damage. Two more explosions on 6 October led to ashfall reported from Zacualpan de Amilpas (30 km SW) and Tetela del volcán (18 km SW) (figure 97). The Washington VAAC reported the 6 October emissions at 6.4 km altitude.

Figure (see Caption) Figure 97. Webcam image showing one of the two explosions on 6 October 2017 at Popocatépetl that caused ashfall in Zacualpan de Amilpas (30 km SW) and Tetela del volcán (18 km SW). The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

The first of two explosions on 7 October 2017, shortly after midnight, produced a plume that rose over 2 km and drifted SW with ashfall reported in Tetela del volcán; incandescent blocks were also sent down the flanks (figure 98). The second explosion produced an ash plume that rose 3 km and drifted NNE. The Washington VAAC reported continuing ash emissions during 7-11 October. Numerous plumes rose to 5.8-9.1 km altitude and drifted in several different directions; the plume extended 130 km SW from the summit on 10 October. CENAPRED reported three explosions on 8 October (figure 99) and two on 9 October. Numerous low-intensity exhalative events during 10-12 October produced ash plumes less than 1 km above the crater that drifted SW. Ashfall was reported in several communities during this time including Ozumba, México City (60 km NW), Milpa Alta (45 km NW), Xochimilco (56 km NW), Tlalpan (68 km NW), Coyoacán (66 km NW), Iztapalapa (57 km NW), Magdalena Contreras (72 km NW), and Iztacalco (64 km NW).

Figure (see Caption) Figure 98. Incandescent blocks visible in this image traveled down the flanks of Popocatépetl during the early morning of 7 October 2017. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.
Figure (see Caption) Figure 99. Multiple explosions from Popocatépetl on 8 October 2017, including the one seen here, caused ashfall in several communities NW of the volcano. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

CENAPRED noted incandescence at the crater during most nights from 14 to 31 October, as well as steam, gas, and minor ash from hundreds of low-intensity emission events each day. The Washington VAAC reported ash emissions visible in satellite imagery on 16, 20-22, and 26 October drifting in several different directions at altitudes of 5.8-7.6 km. The plume observed on 22 October reached 60 km from the summit before dissipating. CENAPRED reported two explosions with ash plumes each day during 25-27 October. The Washington VAAC reported an ash plume on 29 October at 6.1 km altitude drifting E about 35 km from the summit, and another at 6.7 km the following day along with an infrared hotspot visible at the summit.

The Washington VAAC issued multiple daily ash advisories throughout November 2017. CENAPRED reported hundreds of daily low intensity emissions of gas and steam that often contained minor ash; the plumes generally rose about 1 km above the summit and most often drifted SW. They also observed incandescence at the crater on all clear nights. They reported Strombolian activity on 3 November in the early morning that lasted for several hours. Explosions early on 4 November resulted in minor ashfall in Yecapixtla (29 km SW) and Zacualpan de Amilpas and other areas to the SW. A Strombolian episode later that day lasted for about an hour and resulted in minor ashfall in Tetela del Volcán. Another explosion that night sent incandescent fragments 200 m down the flanks.

An explosion on 6 November sent an ash plume 2.5 km above the summit crater that drifted SW and sent incandescent fragments 500 m down the flank. Another explosion during the early morning of 7 November produced a 2-km-high ash plume. Moderate amounts of ash rose 1 km above the summit on 8 November. There were three explosions on 10 November; the largest produced a 3-km-high ash plume that drifted SW. Continuous low-level emission of gas and ash on 14 November resulted in ashfall reported in Totolapan, Yecapixtla, Ocuituco (23 km SW), Tetela del Volcán, and Ecatzingo. An explosion on 17 November sent an ash plume 2.5 km above the summit that drifted SW. During 18-19 November five explosions caused ash plumes to rise 2 km above the summit and incandescent blocks to fall down the E flank.

Around 1030 on 20 November, seismic activity increased and was accompanied by a constant plume of steam, gas, and moderate ash that rose about 1.5 km and drifted E. During 20-21 November eight explosions were reported, with five more the following day. During the afternoon of 23 November a continuous ash emission that lasted 90 minutes drifted SSE at 2 km above the summit, and spread ash over communities to the SSE including Huaquechula (30 km SSE), Tepeojuma (38 km SE), Atlixco (23 km SE), and Izúcar de Matamoros (50 km SE) (figure 100). Another significant ash emission during the afternoon of 24 November sent a column of ash to 4 km above the summit, drifting SSE; it lasted for almost two hours (figure 101). The Washington VAAC reported the plume at 8.5 km altitude. Ashfall was reported in San Pedro Benito Juárez (12 km SE) and Atlixco. Late that evening, an explosion sent incandescent fragments 1 km down the flanks and generated an ash plume that rose to 2.5 km above the summit and also drifted SSE.

Figure (see Caption) Figure 100. A continuous ash emission at Popocatépetl that lasted for 90 minutes drifted SSE at 2 km above the summit, and spread ash over several communities to the SSE on 23 November 2017. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.
Figure (see Caption) Figure 101. A substantial ash emission at Popocatépetl during the afternoon of 24 November 2017 sent a column of ash to 4 km above the summit that drifted SSE; it lasted for almost two hours. The Washington VAAC reported the plume at 8.5 km altitude. The Altzomoni webcam is located about 10 km N of the summit. Courtesy of CENAPRED.

A flyover by CENAPRED and the Federal Police on 25 November 2017 allowed evaluation of the changes in the summit crater from the recent explosions. They noted that the internal crater within the summit crater had increased its dimensions, reaching a diameter of 370 m and a depth of 110 m (figure 102). A 3-km-tall ash plume resulted from continuous emissions that began in the afternoon of 27 November and lasted for two hours. The Washington VAAC reported the plume at 7.9 km altitude. The plume drifted SSE, and dispersed ash over communities in that region including Tochimilco (16 km), Izucar de Matamoros, Atlixco, and Huaquechula.

Figure (see Caption) Figure 102. During a flyover on 25 November 2017, CENAPRED observed that the increased size of the internal summit crater at Popocatépetl was 370 m in diameter and 110 m deep. Courtesy of CENAPRED.

Activity during December 2017-February 2018. The Washington VAAC issued multiple daily reports of ash emissions during 1-12 and 24-31 December 2017. CENAPRED noted hundreds of daily low-intensity emissions of gas and steam, most with small quantities of ash, throughout December, as well as multiple ash emissions on many days that rose generally 1-2.5 km above the summit. In the early morning of 2 December an explosion caused an ash plume to rise 2.5 km above the summit. A second plume rose 1 km later that day; they both drifted SSE. An explosion in the afternoon of 9 December sent an ash plume over 2.5 km above the summit that drifted NE. The Washington VAAC reported the plume at 7.6 km altitude. Later that evening Strombolian activity sent incandescent blocks down the flanks and generated an ash plume that drifted E. Incandescence was observed at the summit crater during the nights of 17-21 and 24-29 December. Continuous emissions of steam, gas, and moderate-density ash were reported drifting NW for about 90 minutes on 29 December. An explosion on 31 December at 1032 generated a 2-km-high ash plume that also drifted NW.

There were multiple daily reports of ash emissions issued by the Washington VAAC during most days of January 2018. CENAPRED noted hundreds of daily low-intensity emissions of gas and steam, many with small quantities of ash, throughout the month, as well as explosions with ash emissions on many days that generally rose 1-2.5 km above the summit. They also observed incandescence at the summit crater multiple days each week. Ongoing low-level emissions of steam, gas, and minor ash were reported during 4-5 January. During the evening of 5 January activity increased, and the ash plume rose to 800 m and drifted SE. In addition, incandescent blocks were ejected 200-300 m down the flanks for about two hours.

An explosion on 18 January 2018 generated an ash plume that rose 1.5 km above the summit and drifted E while incandescent blocks were ejected up to 700 m down the flanks. An episode of Strombolian activity in the early morning of 25 January produced an ash plume that rose 2 km above the summit and drifted N and NE, resulting in reports of ashfall in San Pedro Nexapa (14 km NE) and Amecameca (19 km NE). It lasted for about 2 hours. Four explosions were reported during the afternoon of 29 January and an explosion the following afternoon produced an ash plume that rose more than 3 km above the summit, and was dispersed to the NW. An explosion on 31 January also produced a substantial ash plume that the Washington VAAC reported at 10.3 km altitude moving NNE (figure 103).

Figure (see Caption) Figure 103. An ash plume rose to 10.3 km altitude from Popocatépetl on 31 January 2018 and drifted NNE. The Altzomoni webcam is located about 10 km N of the summit. Courtesy of CENAPRED.

Activity was somewhat quieter at Popocatépetl during February 2018. The Washington VAAC reported ash emissions on 14 days during the month. CENAPRED reported tens, not hundreds, of daily low-intensity emissions of gas and steam that often contained minor amounts of ash. They also noted one or more explosions with ash emissions on many days that rose generally 1-1.5 km above the summit and drifted in various directions. During many clear days they observed nearly constant emissions of steam, gas, and minor ash that reached 500-800 m above the summit. An explosion on 20 February produced an ash plume that rose 1.5 km above the summit. Continuous steam and gas emissions during 22-23 February were accompanied by minor incandescence intermittently observed at the summit.

Satellite data. Sulfur dioxide emissions were large enough to be recorded by satellite instruments several times every month during August 2017-February 2018 (figure 104). Variable wind directions and persistent emissions produced relatively long-lived plumes that dispersed over large areas of Mexico.

Figure (see Caption) Figure 104. The OMI instrument on NASA's AURA satellite recorded evidence of significant monthly SO2 emissions at Popocatépetl, including on 27 September 2017 (upper left), 13 October 2017 (upper right), 31 October 2017 (lower left) and 25 December 2017 (lower right). Variable wind directions and persistent emissions produced relatively long-lived plumes that dispersed over large areas of Mexico. Courtesy of NASA Goddard Space Flight Center.

Thermal anomaly data provided by the MIROVA project are consistent with the visual record of persistent incandescent and explosive activity at the summit (figure 105). Multiple MODVOLC thermal alerts were also recorded every month from October 2017-February 2018.

Figure (see Caption) Figure 105. Thermal anomalies detected by satellite-based MODIS instruments and recorded through the MIROVA project show the pattern of continued moderate-level activity at Popocatépetl during the year ending 12 July 2018. Courtesy of MIROVA.

Geologic Background. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Information Contacts: Centro Nacional de Prevención de Desastres (CENAPRED), Av. Delfín Madrigal No.665. Coyoacan, México D.F. 04360, México (URL: http://www.cenapred.unam.mx/), Daily Report Archive http://www.cenapred.unam.mx:8080/reportesVolcanGobMX/BuscarReportesVolcan); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).


Dukono (Indonesia) — April 2018 Citation iconCite this Report

Dukono

Indonesia

1.693°N, 127.894°E; summit elev. 1229 m

All times are local (unless otherwise noted)


Ongoing ash explosions, thermal anomalies, and sulfur dioxide emissions through March 2018

The current eruption at Dukono has been ongoing since 1933, with frequent explosions and ash plumes between August 2014 and March 2017 (BGVN 42:06). Similar activity has continued during April 2017-March 2018. Monitoring of the volcano is the responsibility of the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG), also known as the Center for Volcanology and Geological Hazard Mitigation (CVGHM).

Thermal measurements made by MODIS satellite instruments and processed by MIROVA show regular low-to-moderate thermal anomalies from April to October 2017 (figure 8), but none after December 2017 or in early 2018. MODVOLC analyses of thermal satellite data identified anomalies on 11 April, 29 April, 9 July, 1 August, and 21 August 2017.

Figure (see Caption) Figure 8. Thermal anomalies recorded by the MIROVA system for the year ending 9 March 2018. Courtesy of MIROVA.

Explosions were frequently reported by both PVMBG and the Darwin Volcanic Ash Advisory Centre (VAAC), with ash plumes rising only a few hundred meters above the Malupang Warirang crater and drifting in various directions (table 17). Some plumes during this reporting period drifted for more than 100 km, with the longest reaching 230 km W on 27 May 2017.

Table 17. Monthly summary of reported ash plumes from Dukono for March 2017-March 2018. The direction of drift for the ash plume through each month is highly variable; only notable significant plumes are listed. Data courtesy of Darwin VAAC and PVMBG.

Month Plume Altitude (km) Notable Plume Drift
Apr 2017 1.8-2.4 --
May 2017 1.8-2.4 230 km W (27 May)
Jun 2017 1.5-3.0 140 km E (07 Jun)
Jul 2017 1.5-2.7 --
Aug 2017 1.8-2.1 150 km (17 Aug)
Sep 2017 1.5-2.4 --
Oct 2017 1.5-2.1 140-170 km (08 Oct)
Nov 2017 1.8-2.3 170 km (04-05 Nov)
Dec 2017 1.8-2.1 --
Jan 2018 2.1 --
Feb 2018 1.5-2.1 --
Mar 2018 1.5-3.0 --

According to NASA Goddard Space Flight Center, SO2 emissions are commonly detected from Dukono, but usually only at low levels, using the Ozone Monitoring Instrument (OMI) aboard NASA's Earth Observing System (EOS) Aura satellite and the Ozone Mapping and Profiler Suite (OMPS) aboard the NASA/NOAA Suomi National Polar-orbiting Partnership (SNPP) satellite. The strongest emissions captured in satellite data during this report period was on 6 March 2018 (figure 9).

Figure (see Caption) Figure 9. Sulfur dioxide emissions from Dukono can be identified using the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite, as seen in this example from 6 March 2018. The highest amount of SO2 (red) is centered over the volcano. Courtesy of NASA Goddard Space Flight Center.

Geologic Background. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Information Contacts: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).

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Bulletin of the Global Volcanism Network - Volume 29, Number 03 (March 2004)

Managing Editor: Richard Wunderman

Ambrym (Vanuatu)

Abundant MODIS thermal alerts during March 2003-February 2004

Bagana (Papua New Guinea)

Abundant MODIS thermal alerts during March 2003-February 2004

Bezymianny (Russia)

Eruptions on 25 December 2002 and January 2004

Chillan, Nevados de (Chile)

A small eruption, the first since 1986, during August-September 2003

Egon (Indonesia)

29 January brings sudden eruptive onset, prompting rapid evacuations

Etna (Italy)

Ashfall with juvenile components, emitted gases, and seismic patterns imply magma ascent

Fournaise, Piton de la (France)

December 2003 lavas spread across 40% of Dolomieu crater floor

Karangetang (Indonesia)

Aviation report, stating ash to 7.5 km; seven MODIS alerts in ~ 1 year

NW Rota-1 (United States)

Minor submarine eruption seen at depth; quiet at West Rota caldera

Saunders (United Kingdom)

A MODIS thermal alert on 7 May 2003 (no secondary confirmation)

Sheveluch (Russia)

Lava dome growth and associated unrest

Stromboli (Italy)

Webcams at various wavelengths document increased explosions in February 2004

Suwanosejima (Japan)

Sporadic eruptions in 2003 and in January 2004, one to 2.4 km altitude

White Island (New Zealand)

Eruptions ceased in about 2002; crater lake rising

Yasur (Vanuatu)

500 explosions/day in March 2004; MODIS thermal alerts average about one per month



Ambrym (Vanuatu) — March 2004 Citation iconCite this Report

Ambrym

Vanuatu

16.25°S, 168.12°E; summit elev. 1334 m

All times are local (unless otherwise noted)


Abundant MODIS thermal alerts during March 2003-February 2004

Ambrym was last reported in BGVN 28:09, when details of activity observed during September 2003 visits were published. A daily summary of MODIS thermal alerts for the year ending February 2004 (table 1) suggests, subject to the limitations of thermal imaging (e.g. in times of heavy cloud), regular activity over the course of the year. No corroborative reports of activity have been received from the [Départment de la Géologie, des Mines et des Ressources,] or the Darwin Volcanic Ash Advisory Centre.

Table 1. Nights on which MODIS thermal alerts were recorded for Ambrym, for the year ending February 2004 . Thermal alerts recorded in daylight hours have been omitted for data reliability reasons (four cases). Data courtesy HIGP MODIS Thermal Alert System.

Month Days with Thermal Alerts
Mar 2003 7, 21, 30
Apr 2003 15, 17
May 2003 1, 3, 17, 19, 20, 28
Jun 2003 9, 15, 16, 29
Jul 2003 29
Aug 2003 21, 25
Sep 2003 13, 15, 24
Oct 2003 1, 3, 8, 10, 22, 24, 31
Nov 2003 2
Dec 2003 25, 27
Jan 2004 7, 9, 12, 28
Feb 2004 1, 3, 4, 10, 17, 19, 22, 28

Geologic Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.

Information Contacts: HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/).


Bagana (Papua New Guinea) — March 2004 Citation iconCite this Report

Bagana

Papua New Guinea

6.137°S, 155.196°E; summit elev. 1855 m

All times are local (unless otherwise noted)


Abundant MODIS thermal alerts during March 2003-February 2004

Continued MODIS thermal alerts during March 2003-February 2004 (table 2) suggests that activity continued over the year ending February 2004. No corroborative reports of activity have been received from the Rabaul Volcano Observatory or the Darwin Volcanic Ash Advisory Centre.

Table 2. Nights on which MODIS thermal alerts were recorded for Bagana, for the year ending February 2004. Thermal alerts recorded in daylight hours have been omitted for data reliability reasons (one case on 23 October 2003). Data courtesy HIGP MODIS Thermal Alert System.

[Skip text table]
    Month       Days with Thermal Alerts

    Mar 2003    13, 19, 26, 31
    Apr 2003    2, 11, 18, 25
    May 2003    18, 20
    Jun 2003    19, 26
    Jul 2003    21, 23, 25
    Aug 2003    4, 6, 8, 13, 24, 29
    Sep 2003    16
    Oct 2003    2, 4, 07, 13, 18, 27
    Nov 2003    5, 10, 12
    Dec 2003    3
    Jan 2004    13, 15, 20, 24, 31
    Feb 2004    5

Geologic Background. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Information Contacts: HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/).


Bezymianny (Russia) — March 2004 Citation iconCite this Report

Bezymianny

Russia

55.972°N, 160.595°E; summit elev. 2882 m

All times are local (unless otherwise noted)


Eruptions on 25 December 2002 and January 2004

Kamchatka Volcanic Eruptions Response Team (KVERT) reports, through the Alaska Volcano Observatory (AVO), indicate that a weak thermal anomaly registered on satellite images following the 26 July 2003 eruption and continuing until an eruption on 14 January 2004.

January 2004 eruption. A shallow earthquake of local magnitude (Ml) 2.2 was reported at Bezymianny on 9 January. The eruption itself began at 1053 on 14 January, sending ash plumes to 6-8 km altitude to the ENE, decreasing to 3.5 km altitude later in the day. KVERT reported that a large pyroclastic flow probably formed on the ESE flank. On 15 January, gas-steam plumes rose to 100 m above the lava dome, increasing to 500 m on 16 January. A 2- to 8-pixel thermal anomaly registered on these days. Satellite images on the morning of 14 January showed ash clouds about 30 km wide extending 150 ENE km, increasing to 250-300 km ENE that afternoon. Meaningful seismic monitoring was thwarted during the eruption period due to high-level volcanic tremor at nearby Kliuchevskoi volcano. The eruption caused the hazard status to temporarily rise to the highest level (red).

KVERT weekly reports for the period from the 14 January eruption to 16 April indicate continuing unrest at Bezymianny. The lava dome was reported to be growing, with no detectable seismicity, gas-steam plumes were rising ~ 3-4 km and dispersing in the wind (generally to the S), and the number of pixels in thermal anomalies reduced from 1-4 early in the period to 1-2 late in the period.

25 December 2002 eruption. A substantial eruption at Bezymianny on 25 December 2002 was not reported in the Bulletin. That eruption followed a 1-pixel thermal anomaly on 23 December that increased to 7-10 pixels on 24-25 December, with seismicity slightly above background levels. Weak intermittent spasmodic tremor occurred on the 25th, when a very hot plume that probably contained ash was visible, and moderate explosive activity began around 1900. Seismic data revealed a large explosive eruption on 26 December at 0715. The resultant ash cloud rose to 5 km altitude. and deposited ash in Kozyrevsk, 55 km NW of Bezymianny. The eruption continued through the 27th, but activity decreased. On 1 January 2003 a weak thermal anomaly was noted over the volcano, probably reflecting a viscous lava flow on the dome.

Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia, the Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.


Nevados de Chillan (Chile) — March 2004 Citation iconCite this Report

Nevados de Chillan

Chile

36.868°S, 71.378°W; summit elev. 3180 m

All times are local (unless otherwise noted)


A small eruption, the first since 1986, during August-September 2003

Nevados de Chillán was active from 1973 through 1983; after that, phreatomagmatic eruptions were reported to have almost ended. A small (VEI 1) eruption, the first since 1986, was noted by local inhabitants and tourists in August-September 2003. Low magnitude explosive events occurred over the week ending 27 August 2003, sending brown-gray to white gas-and-ash columns up to heights of 500 m for periods of up to 25 minutes. Resulting deposits were ~ 1 cm deep over a sharply defined 2.2 km wide zone to the SSE. Prevailing winds were strong around the time of the eruption (figure 2). Explosions then became more sporadic, occurring at 2-3 day intervals, until ceasing in mid-September.

Figure (see Caption) Figure 2. Strong prevailing winds blowing over the Nevados de Chillán complex caused the resulting plume to remain at low altitude. This photo was taken in early September 2003. The plume blew towards the SSE. Courtesy Servicio Nacional de Geoligica y Mineria.

An inspection of the eruption site on 22 January 2004 by Servicio Nacional de Geoligica y Mineria scientists revealed a new compound, fissure-like, double crater in the saddle between the cones Nuevo (which erupted during 1906-1945) and Arrau (which erupted during 1973-1986) (figure 3). This new ~ 64 m long double crater consisted of a NW situated, 25 x 14 m crater and a SE situated, 39 x 28 m crater. These craters lie to the NW of Arrau cone and become surrounded by an area of intense fumaroles towards Nuevo cone. The fumaroles are water-vapor rich but give off a weak sulfur odor. On Nuevo's E side they had temperatures of up to 88°C (table 1). While no previous measurements were available, this area showed more intense fumarolic activity than seen during a January 1994 visit and 1998 air photographs. During the recent visit the local heat-flow appeared concentrated adjacent to Nuevo cone, rather than Arrau cone. This, and the fissure-like form of the 2003 crater, were taken as evidence for possible future eruptions closer to Nuevo cone.

Figure (see Caption) Figure 3. Aerial view and cross section of the Nevados de Chillán complex, showing the new crater in relation to Nuevo and Arrau cones, and indicating SSE-oriented ash dispersal. Courtesy Servicio Nacional de Geoligica y Mineria.

Table 1. Site names, locations (as UTM coordinates), and fumarole temperatures describing conditions at Nevados de Chillán on 22 January 2004. The fumaroles were located near the 2003 vent. Courtesy of J.A. Naranjo and L.E. Lara, SERNAGEOMIN.

Site UTM N UTM W Temperature (°C ± 0.5)
SW Nuevo flank 288.086 5916.963 87.2
E Nuevo rim 288.138 5917.522 87.9
Between craters 288.263 5917.547 57.4

In addition to dispersal and deposition of loose ash, the January inspection noted agglutinates forming a series of 2 m long ridges or 'dunes' (figure 4). The agglutinates consisted of wet black clusters of ash spheres with 0.5- to 1-cm diameters. A large number of dead insects in the agglutinated ash suggested extreme conditions such as the presence of toxic gasses. When dry, the ash was dark gray with a lithic-rich polymodal composition. Particle sizes ranged from dust to 4-5 mm, of which 5-10% was coarse-grained, lithic-rich lapilli composed of black, gray, and red aphyric andesites and ~ 60% was fine- to medium-grained lapilli composed of lithic clasts, quartz, and plagioclase crystals. Below the 1 mm size range, black glassy shards appeared with cleaved vesicle surfaces and blocky or plate-like shapes. The remnant fraction was light-gray fine ash.

Figure (see Caption) Figure 4. January 2004 view of dried ash deposits from Nevados de Chillán's 2003 eruption. The darker deposits lay atop remnant snow pack. Courtesy Servicio Nacional de Geoligica y Mineria.

Reference. Naranjo, J.A., and Lara, L.E., 2004, August-September 2003 small vulcanian eruption at the Nevados de Chillán Volcanic Complex (36°50'S), Southern Andes (Chile). Revista Geológica de Chile, Vol. 31, No. 2, p. 359-366. DOI: 10.4067/S0716-02082004000200011.

Geologic Background. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.

Information Contacts: Jose A. Naranjo and Luis E. Lara, Servicio Nacional de Geoligica y Mineria (SERNAGEOMIN), Av. Santa Maria 0104, Santiago, Chile.


Egon (Indonesia) — March 2004 Citation iconCite this Report

Egon

Indonesia

8.676°S, 122.455°E; summit elev. 1661 m

All times are local (unless otherwise noted)


29 January brings sudden eruptive onset, prompting rapid evacuations

This first Bulletin report discussing Egon describes the sudden appearance of volcanic activity there in January 2004. Heavy rains fell over Egon and its surrounding area on 28 January. At 0400 on 29 January, local people heard the sound of the E crater wall collapsing inward. That was followed at 1700 by an explosion and a black ash cloud rising ~ 750 m above the summit. On 30-31 January further noise was followed by gray ash clouds and the odor of highly concentrated sulfur every 50-60 minutes. Visual observation on 31 January revealed a new solfatara.

Volcanic earthquakes were detected on 30 January (intensity III on the Modified Mercali (MMI) scale), and a seismometer installed on 31 January recorded a type-A deep-volcanic earthquake at 1610 and two harmonic tremor events (amplitude 0.5 mm) at 1800. At 2227 an explosion was heard and instrumentally recorded for about 70 seconds. On 1 February, instruments recorded two tremor events and one type-A volcanic earthquake. Egon was placed on Alert level 3 (on a 1-4 scale) on that day.

United Nations reports and news reports from around 31 January indicated that up to 6,400 people were being evacuated from near Egon volcano as a precautionary measure due to "smoke," ash, and other possible emissions. The news cited evacuations from the mountain villages of Hale, Hebing, Lere, Natakoli, Pedat, Bau Krengat, and Kelawair, with refugees going to Maumere (the island's main town, 25 km W of the summit). There were reports of 1 or 2 deaths, but it is not entirely clear that they were related to volcanic activity, evacuations, or other causes.

The European Volcanological Society (SVE) posted this report on the UN's Relief Web website: "One person has been reported killed from smoke and ash inhalation from the eruption of Egon volcano. Thick clouds of smoke and a great discharge of hot ash, large chunks of sulfur and volcanic rocks were seen nearby. The eruption caused panic among residents nearby, and they fled the mountain villages . . . . Eyewitnesses said the lower part of the crater was seen bursting and that was believed to be the main outlet for the hot lava that spewed from the volcano.."

Agence France-Presse published a photo (by Romeo Gacad) with a distant aerial view of Egon's summit as it appeared around sunset on 1 February. A thin plume rose gently above the summit. Lower portions of the photo were in cloud.

A 2 February 2004 United Nations (OCHA) report stated that "Volcanologists continue monitoring the activity of Mt. Egon closely. Since the beginning of February, a decrease in seismic activity and emissions has been registered." This and another UN report noted, as of 13 February ~ 5,000 people had been evacuated and had been accommodated in 14 temporary government shelters. The report went on to note "A gradual return of the evacuated population has already begun and is expected to continue if current conditions remain unchanged. As of 4 February some 600 people have already returned to their villages."

Geologic Background. Gunung Egon, also known as Namang, sits astride the narrow waist of eastern Flores Island. The barren, sparsely vegetated summit region has a 350-m-wide, 200-m-deep crater that sometimes contains a lake. Other small crater lakes occur on the flanks. A lava dome forms the southern summit. Solfataric activity occurs on the crater wall and rim and on the upper S flank. Reports of historical eruptive activity prior to explosive eruptions beginning in 2004 were inconclusive. A column of "smoke" was often observed above the summit during 1888-1891 and in 1892. Strong "smoke" emission in 1907 reported by Sapper (1917) was considered by the Catalog of Active Volcanoes of the World (Neumann van Padang, 1951) to be an historical eruption, but Kemmerling (1929) noted that this was likely confused with an eruption on the same date and time from Lewotobi Lakilaki.

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Directorate of Volcanology and Geological Hazards (formerly VSI), Jalan Diponegoro No 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Dan Shackelford, 3124 E. Yorba Linda Blvd., Apt. H-33, Fullerton, CA 92831-2324, USA; United Nations, Office for the Coordination of Humanitarian Affairs (UN OCHA), S-3600, New York, NY 10017, USA (URL: https://reliefweb.int/); Henry Gaudru, Société Volcanologique Européenne (SVE), C.P.1-1211 Geneva 17- Switzerland (URL: http://www.sveurop.org/).


Etna (Italy) — March 2004 Citation iconCite this Report

Etna

Italy

37.748°N, 14.999°E; summit elev. 3295 m

All times are local (unless otherwise noted)


Ashfall with juvenile components, emitted gases, and seismic patterns imply magma ascent

Since the cessation of the last eruption of Mount Etna on 28 January 2003, no further eruptive activity has been observed. Summit activity has been limited to pulsating gas emissions from the Northeast Crater (NEC) and from one of the two vents within Bocca Nuova (BN). The other central crater vents and the Southeast Crater (SEC) were essentially blocked and only producing extremely weak gas emissions.

The first significant variation from this very low level of activity was seen between 12 and 14 February 2004, when a weak ash emission was observed within the summit crater plume. A fresh ash sample was collected in Pedara, a village about 10 km SE from the summit. Del Carlo and Andronico (2004) reported that the sample was made up of material with a grain-size less than 0.125 mm. Components comprising the sample consisted of sideromelane (41.5%), tachylite (24.7%), loose crystals of clinopyroxene, olivine, and plagioclase (4%), and lithics (29.7%). The clasts of sideromelane were very vesiculated and made of light-brown, transparent and shiny glass. There were also a few strands of Pele's hair. Tachylites were black or gray, shiny, sub-angular clasts. Lithics comprised fragments of weathered scoria, lavas, or secondary minerals. The high amount of juvenile components within the ash were taken to suggests an uprise of magma into the summit feeder conduit, the first to occur since the end of the 2002-2003 flank eruption.

The INGV-CT Geochemistry group performed regular remote-sensing measurements of volcanic gas flux and chemical composition on Etna using COSPEC and FTIR instruments. Such measurements demonstrated that the upper conduit system of Mt Etna has been weakly supplied with magma since the end of the 2002-2003 eruption, an observation supported both by relatively low fluxes of SO2 and low molar ratios of SO2/HCl. Occasional discrete injections of magma into the upper conduit system have been observed, however, as sharp increases in both SO2 flux and SO2/HCl ratios. These inputs occurred in August 2003, December 2003, and in late January 2004.

The INGV-CT permanent seismic network consisted of ~ 40 stations, 10 of which were installed in October 2003 and have broad-band, 40-second-period sensors. After the end of the 2002-2003 flank eruption, seismicity was mainly concentrated along Etna's E and NE flanks, appearing in two main phases. Until the end of May 2003, earthquakes were localized along the same structures that were activated during the 2002-2003 eruption, suggesting a relaxation phase. During this phase, several swarms occurred mainly between 3 and 7 km depth, showing a progressive decrease in seismic energy. After June 2003, several shallow earthquakes were recorded along the upper eastern part of the volcanic edifice near Zafferana, and along the Pernicana fault on the NE flank. This second phase was characterized by a renewal of seismic activity, with several seismic swarms characterized by progressive release of seismic energy. In particular, during the last two months, the Pernicana Fault has been very active (UFS Weekly Reports, 2003 and 2004).

References. Del Carlo, P., and Andronico, D., 2004, Rapporto cenere Etna del 13-14/02/04: INGV-CT Internal Report, Prot. Int. no. UFVG2004/024, p 1. UFS INGV-CT Weekly Internal Reports, 2003 and 2004.

Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Information Contacts: Sonia Calvari, Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/).


Piton de la Fournaise (France) — March 2004 Citation iconCite this Report

Piton de la Fournaise

France

21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)


December 2003 lavas spread across 40% of Dolomieu crater floor

BGVN 28:09 reported a seismic crisis and new SSW-flank fissure at Piton de la Fournaise on 30 September 2003. The Volcanological Observatory monitoring Piton de la Fournaise and the local press reported a further seismic crisis that developed on 7 December 2003 at 1429 beneath the summit. Following around an hour of seismicity, an eruption began on 7 December at 1535 in the Dolomieu crater, with lava fountaining to ten's of meters from two fractures on the SE crater floor. Two new fractures were also observed on the S crater rim that did not produce lava. The eruption decreased rapidly over the night of 7-8 December. By 8 December at about 1400 small incandescent lava flows and rock falls on the S crater wall were observed. By the night of 8 December the eruption ceased but strong degassing and fluctuating seismicity continued. New lava covered ~ 40% of the Dolomieu crater floor.

The eruption was preceded by a seismic swarm on 6 November that was followed by ~ 30 cm of steady uplift and 10-20 earthquakes recorded per day. As of 16 December, significant seismic activity continued, and hikers were permitted only limited access. Press reports indicated three quite active cones within the S rampart of the Dolomieu crater, surrounded by ejecta found more than 200 m N, noisy degassing, lava covering the bottom of the crater up to 5 m thick, and zigzag cracks crossing the crater's S exterior.

A further seismic event with significant surface deformation occurred over 7-9 January 2004.

[On 9 January eruption tremor started near Nez Coupé de Sainte Rose. A 300-m-long fissure, cutting the 1931 crater, produced a small ~2-km-long lava flow. The eruption stopped on 10 January around 1200.]

Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: Thomas Staudacher, Observatoire Volcanologique du Piton de la Fournaise Institut de Physique du Globe de Paris, 97418 La Plaine des Cafres, La Réunion, France (URL: http://www.ipgp.fr/fr/ovpf/observatoire-volcanologique-piton-de-fournaise).


Karangetang (Indonesia) — March 2004 Citation iconCite this Report

Karangetang

Indonesia

2.781°N, 125.407°E; summit elev. 1797 m

All times are local (unless otherwise noted)


Aviation report, stating ash to 7.5 km; seven MODIS alerts in ~ 1 year

A Darwin Volcanic Ash Advisory Centre report stated that at 0630 UTC (1430 local time) on 18 July 2003 pilots saw a thick ash plume rising from the volcano to ~ 8.5 km altitude.

HIGP MODIS thermal-alert reports for the year to 13 April 2004 showed, subject to the limitations of thermal imaging (e.g. in times of heavy cloud), thermal activity at the volcano on 26 April, 7 and 30 May, 1 and 6 June, 21 July and 11 August 2003, and 2 April 2004.

Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Information Contacts: HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Commonwealth Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vacc/).


NW Rota-1 (United States) — March 2004 Citation iconCite this Report

NW Rota-1

United States

14.601°N, 144.775°E; summit elev. -517 m

All times are local (unless otherwise noted)


Minor submarine eruption seen at depth; quiet at West Rota caldera

The research vessel Thomas G. Thompson conducted a survey of the Mariana Arc in the Commonwealth of the Northern Mariana Islands from 9 February to 5 March 2003 (Embley and others, 2004). That survey identified a number of hydrothermal systems (plumes) on the arc volcanoes. One volcano, detected in 2003 and named "NW Rota 1," was revisited in 2004 and again found to be actively venting (figure 1). That submarine volcano sits ~ 64 km NW of the island of Rota, with its summit at 14°36.048'N, 144°46.519'E (14.601°N, 144.775°E). Another volcano visited in 2003-2004 was an apparently quiet, non-erupting caldera lacking eruptive age constraints called "West Rota" (discussed at the end of this report). Most of the information gleaned from the 2004 cruise remains preliminary, coming from scientists still at sea.

Figure (see Caption) Figure 1. A map showing part of the Northern Mariana Islands and vicinity (an area roughly midway between the main island of New Guinea on the S, and Tokyo, Japan on the N). The islands shown include Guam, Rota, Saipan, and others. The map emphasizes the location of the active submarine volcano NW Rota 1 and the currently quiet submarine caldera West Rota. After Embley and others, 2004; courtesy of the American Geophysical Union.

The ship towed a conductivity-temperature-depth (CTD)/rosette system to map and sample hydrothermal plumes over NW Rota 1. The 2003 tow data detected a vigorous, 200-m-thick layer of hydrothermal plumes above the volcano's summit. Chemical analysis of the 2003 plumes found high concentrations of particulate aluminum, sulfur, iron, and manganese, along with elevated 3He, a helium isotope considered diagnostic of a magmatic source and associated hydrothermal discharge. The active crater's summit depth was ~ 517 m.

[During 27 March-18 April 2004], the RV Thompson revisited the Mariana Arc and found NW Rota 1 still vigorously active. William Chadwick and Robert Embley, National Oceanographic and Atmospheric Agency (NOAA), members of the cruise scientific staff, notified GVN that some video images from NW Rota 1 were taken with a ship-deployed remote vehicle (ROPOS-Remotely Operated Platform for Ocean Science). Videos posted on their web page showed views of the so-called "Brimstone Pit" (figures 2 and 3). Brimstone Pit represents a S-flank vent at a depth of 555 m, a spot ~ 40 m below the summit in rocky terrain. The videos and photos showed ash and sulfur bursts from the crater and a vent whose rim was covered with spatter (but probably not from this specific event). Water samples taken in a plume rising from the vent had temperatures of 30°C. Although incompletely mapped, the vent was roughly 20 m across and elliptical in outline; in the vertical dimension the vent appeared ~ 12 m deep and funnel-shaped.

Figure (see Caption) Figure 2. Bathymetry of NW Rota 1 showing the location of Brimstone Pit, [March 2004]. Courtesy of Bob Embley, NOAA.
Figure (see Caption) Figure 3. At NW Rota 1, the 555-m-deep submarine crater called Brimstone Pit discharged a dense, yellowish, particle-laden plume. This [30 March] 2004 photo was taken from a remote submarine vehicle, which captured the plume from the submarine vantage point, a relatively rare circumstance for shallow-depth submarine eruptions. At other times during the exploration, venting slowed or ceased, allowing views of the vent itself. Courtesy of W. Chadwick, NOAA.

During the ROPOS dive, the activity at the crater was variable. At the beginning of the dive there was only a wispy plume escaping, allowing the observers to see into the crater. Later in the dive, the crater returned to pulsing activity with bigger, more vigorous plumes and small rocks raining down on the crater rim. Over the summit, which was still at a depth of ~ 517 m below sea level (as it was in 2003), the ROPOS images depicted a lot of diffuse venting of clear fluids. Intense geyser-like discharges flowed from the vents with jets rising to several ten's of meters. Cloudy water rose to form a plume several hundred meters above the summit. The pulsating jets carried sand- to gravel-size particles (a few centimeters across), ejecta that rained down on the crater rim out to a distance of ~ 10 m. Droplets of molten sulfur in the jets gave a yellowish cast to the billowing clouds, suggesting a temperature of at least 100°C (figure 3). The ROPOS came up from the last dive covered in sand and gravel, and in sulfur droplets, which had solidified and adhered to the submersible's body!

In overview, the [30-31 March 2004] dives with ROPOS documented NW Rota 1 in a magmatic phase of activity. The active vent showed time-varying behavior that included precipitation of sulfur droplets from the venting fluids, pulses of ejecta from the vent, and large amounts of fresh, glassy ejecta surrounding the crater. In addition, the study identified a turbid plume extending ~ 0.7-2.0 km from the volcano, reflecting an intensity unseen in 2003, and presumably the result of the vigorous summit activity.

The large amount of sulfur was believed to be forming by interaction of magmatic SO2 with water to form elemental sulfur and sulfurous acids. Bob Embley suggested that this magmatic event was in the early stages, as evidenced by negligible alteration of glassy lavas in spite of incredibly corrosive hot fluids. Team biologists noted that biota had only begun to colonize the impacted area.

Volcanic seismicity may accompany this event, although its detection may require a network of near-source ocean-bottom seismometers. At least from initial looks at their data, geophysicists at the NOAA Vents Program failed to detect any T-phase hydroacoustic signals coming from this vicinity. It should be noted, however, that their real-time hydrophones are located in the NE Pacific at a great distance from the volcano.

In an effort to enlist other seismic and acoustical instruments, Olivier Hyvernaud (Laboratoire de Détection et de Géophysique, CEA/DASE/LDG; with access to the French Polynesian network), and Roderick Stewart (CTBTO, the Preparatory Commission for the comprehensive nuclear-test-ban treaty, with access to Juan Fernandez island data) have been contacted. Thus far it appears that their systems lacked signals clearly attributable to NW Rota 1.

West Rota. During early April 2004 the RV Thompson also visited another newly identified submarine volcano that the 2003 survey group named "West Rota" (~ 56 km W of the island of Rota). It appeared inactive, and lacked a strong hydrothermal plume in the waters above it. However, it contained features indicative of a violent explosive eruption at some unknown time in the (geologically) recent past; namely, felsic volcanic rocks and the formation of a big caldera. The West Rota caldera is comparable in size to Crater Lake, Oregon (figure 4). The cruise scientists suspect that this volcano erupted violently a few thousand, to ten's of thousands, of years ago.

Figure (see Caption) Figure 4. Although the erupting submarine volcano NW Rota 1 sits ~ 64 km NW of the island of Rota; slightly more to the W of Rota lies the recently identified and apparently quiet submarine caldera named West Rota. West Rota is elongate in the NW-SE direction and bears approximate size resemblance to the scenic lake-filled, 10-km-diameter caldera in the Cascade range of Oregon (USA), Crater Lake. West Rota's caldera floor lies at ~ 1.6 km depth below sea level. Courtesy of NOAA.

References. Embley, R.W., Baker, E.T., Chadwick, Jr., W.W., Lupton, J.E., Resing, J.A., Massoth, G.J., and Nakamura, K., 2004, Explorations of Mariana Arc volcanoes reveal new hydrothermal systems: EOS-Transactions of the American Geophysical Union, v. 85, no. 4, p. 37 and 40.

Geologic Background. A submarine volcano detected during a 2003 NOAA bathymetric survey of the Mariana Island arc was found to be hydrothermally active and named NW Rota-1. The basaltic to basaltic-andesite seamount rises to within 517 m of the sea surface SW of Esmeralda Bank and lies 64 km NW of Rota Island and about 100 km north of Guam. When Northwest Rota-1 was revisited in 2004, a minor submarine eruption from a vent named Brimstone Pit on the upper south flank about 40 m below the summit intermittently ejected a plume several hundred meters high containing ash, rock particles, and molten sulfur droplets that adhered to the surface of the remotely operated submersible vehicle. The active vent was funnel-shaped, about 20 m wide and 12 m deep. NW Rota-1 is a large submarine volcano with prominent structural lineaments about a kilometer apart cutting across the summit of the edifice and down the NE and SW flanks.

Information Contacts: William W. Chadwick, Jr., Cooperative Institute for Marine Resources Studies (CIMRS), NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE OSU Drive, Newport, OR 97365 USA; Robert W. Embley, NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE OSU Drive, Newport, OR 97365 USA (URL: http://oceanexplorer.noaa.gov/explorations/04fire/welcome.html); Douglas Wiens, Department of Earth and Planetary Sciences, Washington University, Campus Box 1169, One Brookings Drive, Saint Louis, MO 63130-4899, USA (URL: http://epsc.wustl.edu/seismology/).


Saunders (United Kingdom) — March 2004 Citation iconCite this Report

Saunders

United Kingdom

57.8°S, 26.483°W; summit elev. 843 m

All times are local (unless otherwise noted)


A MODIS thermal alert on 7 May 2003 (no secondary confirmation)

The only previous report on the remote Michael volcano was in BGVN 28:02, which commented on a lava lake detected by satellite imagery over the period 1995-2002. A review of MODIS data for the period from that report (end 2002) to 16 March 2004 (UTC) reveals one thermal alert, on 7 May 2003 (UTC). No corroborative report is available, although previous alerts were interpreted as possibly representing lava lake activity.

Geologic Background. Saunders Island is a volcanic structure consisting of a large central edifice intersected by two seamount chains, as shown by bathymetric mapping (Leat et al., 2013). The young constructional Mount Michael stratovolcano dominates the glacier-covered island, while two submarine plateaus, Harpers Bank and Saunders Bank, extend north. The symmetrical Michael has a 500-m-wide summit crater and a remnant of a somma rim to the SE. Tephra layers visible in ice cliffs surrounding the island are evidence of recent eruptions. Ash clouds were reported from the summit crater in 1819, and an effusive eruption was inferred to have occurred from a N-flank fissure around the end of the 19th century and beginning of the 20th century. A low ice-free lava platform, Blackstone Plain, is located on the north coast, surrounding a group of former sea stacks. A cluster of parasitic cones on the SE flank, the Ashen Hills, appear to have been modified since 1820 (LeMasurier and Thomson, 1990). Vapor emission is frequently reported from the summit crater. Recent AVHRR and MODIS satellite imagery has revealed evidence for lava lake activity in the summit crater.

Information Contacts: Rob Wright, Luke Flynn, and Eric Pilger; MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/).


Sheveluch (Russia) — March 2004 Citation iconCite this Report

Sheveluch

Russia

56.653°N, 161.36°E; summit elev. 3283 m

All times are local (unless otherwise noted)


Lava dome growth and associated unrest

Unrest at Shiveluch continued from 1 January through 9 April 2004, including above-background seismicity and lava-dome growth with associated pyroclastic flows. Gas-and-steam plumes rising as high as 4.5 km altitude and ash plumes rising to 4-6 km altitude were frequent. Plumes were noted as far as 175 km from the volcano. During the period, US and Russian satellites repeatedly detected thermal anomalies. For viewers on the ground the volcano was obscured by clouds throughout much of the period.

Earthquakes occurred at depths of 0-5 km with local magnitudes (Ml) of 1.25-2.6. About 70 shallow earthquakes with Ml over 1.75 occurred during the week ending 16 January. These were exceeded the following week by 206 earthquakes with Ml of 1.75-2.6 and about 40 ash explosions. Intermittent spasmodic volcanic tremors of 0.5-1.0 µm/s were also recorded that week. These events caused the level of concern to raise from Yellow to Orange, where it remained throughout the remainder of the report period.

Accompanying these events were pyroclastic flows with run-out distances of 1-2 km. Ash plumes rose as high as 6 km, extending in various directions for several kilometers. Gas-and-steam plumes rose to 3.5-4.5 km. One extended 50 km to the SE on 22 January while another, on 26 January, extended over 75 km to the SW.

Events and activities similar to those described above were noted throughout the report period. Shallow earthquakes were recorded almost daily through February, >10/week was typical except for the period in late January noted earlier. However, during late February and through March and April, strong earthquakes occurred, numbering 14-24 per week. Spasmodic volcanic tremor was registered throughout this latter period, attaining a maximum velocity of 0.8 µm/s during 4-6 March.

Gas-and-steam plumes, some containing ash and extending as far as 175 km, were noted throughout the period. During the beginning of April, one ash-gas explosion delivered ash up to 9.0 km while 13 other explosions sent plumes up to 4.0-7.2 km and spasmodic tremor with velocities of 0.2-0.7 µm/s was recorded.

Geologic Background. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia, the Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.


Stromboli (Italy) — March 2004 Citation iconCite this Report

Stromboli

Italy

38.789°N, 15.213°E; summit elev. 924 m

All times are local (unless otherwise noted)


Webcams at various wavelengths document increased explosions in February 2004

Explosive activity at the summit craters of Stromboli volcano resumed in early June 2003, before the end of the effusive eruption that finished between 21 and 22 July 2003. Eruptive activity at this volcano is monitored by Istituto Nazionale di Geofisica e Vulcanologia (INGV-CT). They have installed two web cameras at an elevation of 920 m on Il Pizzo Sopra la Fossa and at an elevation of 400 m along the E margin of the Sciara del Fuoco, the depression on the N flank of the volcano. Additionally, a web thermal camera is located at the 400-m elevation site noted above, and a web infrared camera is positioned at Il Pizzo Sopra la Fossa. The 2 cameras (thermal and video) at the 400-m elevation site give important insights when visibility is insufficient at the more distant cameras. The infrared camera at Il Pizzo provides both a continuous view of the activity at the summit craters and a quantification of the energy released by the explosions at the three summit craters through an automated system called VAMOS (Cristaldi and others, 2004).

According to aviation reports from the U.S. Air Force, the web camera at Stromboli captured shots of light ash emissions on 7 and 11 November 2003. In both cases plumes rose to ~ 2.5 km altitude. According to the Toulouse VAAC the Stromboli Web video camera showed a small explosion on 10 December that produced a plume to a height of ~ 1 km above the volcano. No ash was visible on satellite imagery.

According to the INGV-CT, explosive activity at the three summit craters increased after 10 February 2004, leading to a significant growth of the cinder cones inside the craters. Several powerful explosions, especially from crater 1 (the NE-crater) and crater 3 (the SW-crater) carried scoriae 200 m above the craters. These explosions led to fallout of fresh bombs and lapilli on Il Pizzo Sopra la Fossa (the top of the volcano, ~ 100 m above the crater terrace) in early March. Samples of lapilli and scoriae collected on Stromboli by local guides have been analyzed with the scanning electron microscope and microanalysis instruments of INGV-CT (Corsaro and others, 2004). Measurements of glass compositions indicated that products erupted until 25 February 2004 are related to the black scoriaceous volcanics normally erupted during Strombolian activity. Golden basaltic pumices were absent from available samples; such pumices at this volcano have been generally associated with paroxysmal explosive events (Bertagnini and others, 1999) such as that of 5 April 2003. Analysis of components carried out on several ash samples allowed scientists at INGV-CT to recognize sideromelane and tachylite as the main components, making up ~ 80% of the erupted ash (Andronico and others, 2004). The activity of this volcano as of 8 March 2004 can be described, fittingly, as Strombolian with variations in the number and frequency of explosions within normally observed limits, and intensity of explosions at the higher limit of commonly observed activity.

References. Andronico, D., Caruso, S., Cristaldi, A., and Del Carlo, P., 2004, Caratterizzazione delle ceneri emesse dallo Stromboli nel Gennaio-Febbraio 2004: INGV-CT Internal Report, Prot. int. n° UFVG2004/034.

Corsaro, R.A., Miraglia, L., and Zanon, V., 2004, Caratterizzazione dei vetri presenti nei prodotti emessi dallo Stromboli durante il mese di febbraio: 2004 INGV-CT Internal Report, Prot. int. UFVG2004/033.

Cristaldi, A., Contelli, M., and Mangiagli, S., 2004, Rapporto settimanale sull'attivit eruttiva dello Stromboli: 22-29 Febbraio 2004. INGV-CT Internal Report, Prot. int. n° UFVG2004/031 [download at http://www.ct.ingv.it/].

Bertagnini, A., Coltelli, M., Landi, P., Pompilio, M., and Rosi, M., 1999, Violent explosions yield new insights into dynamics of Stromboli volcano. Eos, American Geophysical Union Transactions, 80, 52: 633-636.

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period from about 13,000 to 5000 years ago was followed by formation of the modern edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: Sonia Calvari, Istituto Nazionale di Geofisica e Vulcanologia, Piazza Roma 2, 95123 Catania, Italy (URL: http://www.ct.ingv.it/); Charles Holliday, Air Force Weather Agency (AFWA), Satellite Applications Branch, Offutt AFB, NE 68113-4039, USA.


Suwanosejima (Japan) — March 2004 Citation iconCite this Report

Suwanosejima

Japan

29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)


Sporadic eruptions in 2003 and in January 2004, one to 2.4 km altitude

Suwanose-jima volcano was last reported in BGVN 28:04, when activity was noted in September and December 2002, with thermal anomalies continuing into January 2003. HIGP MODIS thermal imagery revealed only one alert in the year to 13 April 2004, that being on 4 July 2003. NASA Terra and Defense Meteorological Satellite Program imagery dated 7-8 November 2003 showed an ash plume rising from Suwanose-jima to an estimated height of 2,400 m (figure 10) on those days.

Figure (see Caption) Figure 10. Ash plume from Suwanose-jima on 8 November 2003 imaged by the MODIS instrument on the NASA AQUA satellite. Courtesy Defense Meteorological Satellite Program (DMSP) and Charles Holliday.

According to Tokyo VAAC reports, using information from the Japanese Meteorological Agency, explosions also took place at Suwanose-jima on 15 December 2003 at 1946, and 21 December at 1828, each of which produced plumes to an unknown height. The VAAC reported several small emissions on 27 and 28 December, again rising to unknown heights and an eruption on 28 December at 0820 rising to ~ 1.5 km altitude and extending E. On 2, 4 and 21-22 January 2004 small explosions produced ash plumes to unknown heights.

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: Japan Meteorological Agency (JMA), Volcanological Division 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/); HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/); Charles Holliday, Air Force Weather Agency (AFWA), Satellite Applications Branch, Offutt AFB, NE 68113-4039, USA.


White Island (New Zealand) — March 2004 Citation iconCite this Report

White Island

New Zealand

37.52°S, 177.18°E; summit elev. 321 m

All times are local (unless otherwise noted)


Eruptions ceased in about 2002; crater lake rising

An April 2004 note from New Zealand geothermal geologist Ashley Cody noted that White Island had essentially ceased its eruptive episode since about 2002, when it began to emit only very weak gas (lacking ejecta). Accordingly, compared to several years ago, there has been little to report about it. However, the Institute of Geological & Nuclear Sciences (GNS) still monitors White Island seismically, and with the Geonet web camera (visible real-time on the net). This report contains a summary of their brief reports. An issue of current interest is the continued growth of the crater lake. Crater lake growth was previously reported in February and August 2003 (BGVN 28:02 and 28:08).

GNS reports warned that "should there be no significant eruptive activity within the next 18-24 months and the lake continues to fill, it may reach overflow level. In this situation water may overflow into drainage channels on Peg 12 Flat, S of the 1978/90 Crater Complex, and these channels may further erode . . . ."

Steve O'Meara of Volcano Watch International visited White Island on 8 February 2004 (figure 44) and noted considerably weaker fumarolic activity than during an earlier trip in 2000 (figure 45). Hydrothermal activity, though diminished, was still taking place in the crater and steam often lifted off the lake's surface, which effervesced. Scum was weakly present, especially around the lake's edges, but he did not see as much as during his 2000 visit. Volcanic bombs and explosion debris surrounded the crater. Although O'Meara's professionally-guided tour was conducted skillfully and with genuine regard for safety, he expressed concern about a sudden eruption from the lake catching onlookers off guard.

Figure (see Caption) Figure 44. The rim of White island's main crater taken looking W on 8 February 2004, showing the crater lake and the top of the E rim. Observers noted a small fresh landslide in the far crater wall (to the right of the fumaroles). Courtesy of Steve and Donna O'Meara, Volcano Watch International.
Figure (see Caption) Figure 45. A wide-angle aerial shot of White Island taken 5 January 2000 amid much more vigorous degassing than present in February 2004. The then smaller, but more steam-covered crater lake appears in the center of the photo, directly behind the high point along the crater rim in the foreground. Courtesy of Steve and Donna O'Meara, Volcano Watch International.

A 13 February 2004 report from the GNS stated that heavy rainfall on White Island during the past few weeks triggered many small landslides inside the crater rim. They went on to note that the lake continued to fill steadily and last week all of the temporary marker posts were submerged or had washed into the lake. This week, GNS volcanologists had visited the island to install six more survey posts inside the main crater, so changes in the lake's level could continue to be monitored. The lake temperature was 57°C, similar to values measured during the last six months. A 26 March report noted a decrease in the rate of rainfall and consequent drop in the rate of filling of the crater lake. GNS reports on 2 April and 26 March also mentioned minor seismic activity, which was described in more detail in a 19 March report as "including a few very small, discrete earthquakes but no volcanic tremor."

The GNS report for 30 April 2004 stated that "seismic and hydrothermal activity at White Island remain at a low level. The crater lake was then [12-]13.6 m below the level at which it will overflow. White Island also remains at Alert Level 1 (some signs of volcano unrest)." An overview of late 2002-early 2004 GNS data appears on table 11. There were no HIGP-MODIS thermal alert warnings for White Island over the 12 months to April 2004.

Table 11. A summary of the Institute of Geological & Nuclear Sciences (GNS) reports discussing White Island, October 2002 to April 2004. Blank area signify lack of substantive new data. Courtesy of the GNS and their HazardWatch.co.nz website.

[Skip text table]
    Month    Seismicity                         Emission levels
       Comment

    Oct 02      --                              63 metric tons of SO2 / day (t/d)

    Nov 02    Minor weak volcanic tremor        Weak steam / gas emissions

    Dec 02    Minor weak volcanic tremor        Weak steam / gas emissions;
                                                  112 t/d SO2

    Jan 03    Moderate/weak volcanic tremor     Weak steam / gas emissions

    Feb 03    Low / minor volcanic tremor       Minor weak steam / gas emissions;
                                                  269 t/d SO2
       Increased tremor (with exception of 17 Feb)

    Mar 03    Low levels of weak tremor         Low steam / gas emissions;
                                                  267 t/d SO2

    Apr 03    Low / negligible                  Weak / very weak steam / gas plumes
       Active vent flooded, reducing emissions and seismicity

    May 03    Very low                          Unchanged

    Jun 03    Intermittent low-level activity   Minor steam / gas plume

    Jul 03    Very low                          Plume no longer visible
       Light green water, 30 m below rim; 58°C. Fumaroles 101-114°C

    Aug 03    Low                               --
       Water 53°C, 300 m long lake. Active monitoring of water level begins.

Geologic Background. Uninhabited 2 x 2.4 km White Island, one of New Zealand's most active volcanoes, is the emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes; the summit crater appears to be breached to the SE, because the shoreline corresponds to the level of several notches in the SE crater wall. Volckner Rocks, four sea stacks that are remnants of a lava dome, lie 5 km NNE. Intermittent moderate phreatomagmatic and strombolian eruptions have occurred throughout the short historical period beginning in 1826, but its activity also forms a prominent part of Maori legends. Formation of many new vents during the 19th and 20th centuries has produced rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project.

Information Contacts: Institute of Geological & Nuclear Sciences (GNS), Private Bag 2000, Wairakwi, New Zealand (URL: http://www.gns/cri.nz); GeoNet, a project sponsored by the New Zealand Government through these agencies: Earthquake Commission (E.C.), Geological & Nuclear Sciences (GNS), and Foundation for Research, Science & Technology (FAST). Geonet can be contacted at the above GNS address (their URL: http://www.geonet.org.nz/contact.htm); Steve and Donna O'Meara, Volcano Watch International, PO Box 218, Volcano, HI 96785.


Yasur (Vanuatu) — March 2004 Citation iconCite this Report

Yasur

Vanuatu

19.532°S, 169.447°E; summit elev. 361 m

All times are local (unless otherwise noted)


500 explosions/day in March 2004; MODIS thermal alerts average about one per month

Activity from the summit crater at Yasur continued through 2002 (BGVN 28:01). While similar comprehensive reports are not available for 2003, MODIS data (table 2) indicated activity continuing over the year to 16 March 2004. No corroborative reports of activity have been received from the Rabaul Volcano Observatory or the Darwin Volcanic Ash Advisory Centre.

Table 2. Nights on which MODIS thermal alerts were recorded for Yasur during the year ending 16 March 2004. Data courtesy HIGP MODIS Thermal Alert System.

Month Days with Thermal Alerts
Mar 2003 23
Apr 2003 15
May 2003 3, 10
Jun 2003 4
Sep 2003 8, 17
Oct 2003 17, 24, 26
Nov 2003 5, 10, 12
Mar 2004 13

John Seach reported continued eruptions at Yasur during March 2004. He suggested that there was an average of about 500 explosions per day, which is typical of the volcano's normal state of activity.

Geologic Background. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and Vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

Information Contacts: HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/); John Seach, PO Box 4025, Port Vila, Vanuatu (URL: http://www.volcanolive.com/).

Atmospheric Effects

The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

View Atmospheric Effects Reports

Special Announcements

Special announcements of various kinds and obituaries.

View Special Announcements Reports

Additional Reports

Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subregion and subject.

Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge


Additional Reports (database)

08/1997 (BGVN 22:08) False Report of Mount Pinokis Eruption

False report of volcanism intended to exclude would-be gold miners

12/1997 (BGVN 22:12) False Report of Somalia Eruption

Press reports of Somalia's first historical eruption were likely in error

11/1999 (BGVN 24:11) False Report of Sea of Marmara Eruption

UFO adherent claims new volcano in Sea of Marmara

05/2003 (BGVN 28:05) Har-Togoo

Fumaroles and minor seismicity since October 2002

12/2005 (BGVN 30:12) Elgon

False report of activity; confusion caused by burning dung in a lava tube



False Report of Mount Pinokis Eruption (Philippines) — August 1997

False Report of Mount Pinokis Eruption

Philippines

7.975°N, 123.23°E; summit elev. 1510 m

All times are local (unless otherwise noted)


False report of volcanism intended to exclude would-be gold miners

In discussing the week ending on 12 September, "Earthweek" (Newman, 1997) incorrectly claimed that a volcano named "Mount Pinukis" had erupted. Widely read in the US, the dramatic Earthweek report described terrified farmers and a black mushroom cloud that resembled a nuclear explosion. The mountain's location was given as "200 km E of Zamboanga City," a spot well into the sea. The purported eruption had received mention in a Manila Bulletin newspaper report nine days earlier, on 4 September. Their comparatively understated report said that a local police director had disclosed that residents had seen a dormant volcano showing signs of activity.

In response to these news reports Emmanuel Ramos of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) sent a reply on 17 September. PHIVOLCS staff had initially heard that there were some 12 alleged families who fled the mountain and sought shelter in the lowlands. A PHIVOLCS investigation team later found that the reported "families" were actually individuals seeking respite from some politically motivated harassment. The story seems to have stemmed from a local gold rush and an influential politician who wanted to use volcanism as a ploy to exclude residents. PHIVOLCS concluded that no volcanic activity had occurred. They also added that this finding disappointed local politicians but was much welcomed by the residents.

PHIVOLCS spelled the mountain's name as "Pinokis" and from their report it seems that it might be an inactive volcano. There is no known Holocene volcano with a similar name (Simkin and Siebert, 1994). No similar names (Pinokis, Pinukis, Pinakis, etc.) were found listed in the National Imagery and Mapping Agency GEOnet Names Server (http://geonames.nga.mil/gns/html/index.html), a searchable database of 3.3 million non-US geographic-feature names.

The Manila Bulletin report suggested that Pinokis resides on the Zamboanga Peninsula. The Peninsula lies on Mindanao Island's extreme W side where it bounds the Moro Gulf, an arm of the Celebes Sea. The mountainous Peninsula trends NNE-SSW and contains peaks with summit elevations near 1,300 m. Zamboanga City sits at the extreme end of the Peninsula and operates both a major seaport and an international airport.

[Later investigation found that Mt. Pinokis is located in the Lison Valley on the Zamboanga Peninsula, about 170 km NE of Zamboanga City and 30 km NW of Pagadian City. It is adjacent to the two peaks of the Susong Dalaga (Maiden's Breast) and near Mt. Sugarloaf.]

References. Newman, S., 1997, Earthweek, a diary of the planet (week ending 12 September): syndicated newspaper column (URL: http://www.earthweek.com/).

Manila Bulletin, 4 Sept. 1997, Dante's Peak (URL: http://www.mb.com.ph/).

Simkin, T., and Siebert, L., 1994, Volcanoes of the world, 2nd edition: Geoscience Press in association with the Smithsonian Institution Global Volcanism Program, Tucson AZ, 368 p.

Information Contacts: Emmanuel G. Ramos, Deputy Director, Philippine Institute of Volcanology and Seismology, Department of Science and Technology, PHIVOLCS Building, C. P. Garcia Ave., University of the Philippines, Diliman campus, Quezon City, Philippines.


False Report of Somalia Eruption (Somalia) — December 1997

False Report of Somalia Eruption

Somalia

3.25°N, 41.667°E; summit elev. 500 m

All times are local (unless otherwise noted)


Press reports of Somalia's first historical eruption were likely in error

Xinhua News Agency filed a news report on 27 February under the headline "Volcano erupts in Somalia" but the veracity of the story now appears doubtful. The report disclosed the volcano's location as on the W side of the Gedo region, an area along the Ethiopian border just NE of Kenya. The report had relied on the commissioner of the town of Bohol Garas (a settlement described as 40 km NE of the main Al-Itihad headquarters of Luq town) and some or all of the information was relayed by journalists through VHF radio. The report claimed the disaster "wounded six herdsmen" and "claimed the lives of 290 goats grazing near the mountain when the incident took place." Further descriptions included such statements as "the volcano which erupted two days ago [25 February] has melted down the rocks and sand and spread . . . ."

Giday WoldeGabriel returned from three weeks of geological fieldwork in SW Ethiopia, near the Kenyan border, on 25 August. During his time there he inquired of many people, including geologists, if they had heard of a Somalian eruption in the Gedo area; no one had heard of the event. WoldeGabriel stated that he felt the news report could have described an old mine or bomb exploding. Heavy fighting took place in the Gedo region during the Ethio-Somalian war of 1977. Somalia lacks an embassy in Washington DC; when asked during late August, Ayalaw Yiman, an Ethiopian embassy staff member in Washington DC also lacked any knowledge of a Somalian eruption.

A Somalian eruption would be significant since the closest known Holocene volcanoes occur in the central Ethiopian segment of the East African rift system S of Addis Ababa, ~500 km NW of the Gedo area. These Ethiopian rift volcanoes include volcanic fields, shield volcanoes, cinder cones, and stratovolcanoes.

Information Contacts: Xinhua News Agency, 5 Sharp Street West, Wanchai, Hong Kong; Giday WoldeGabriel, EES-1/MS D462, Geology-Geochemistry Group, Los Alamos National Laboratory, Los Alamos, NM 87545; Ayalaw Yiman, Ethiopian Embassy, 2134 Kalorama Rd. NW, Washington DC 20008.


False Report of Sea of Marmara Eruption (Turkey) — November 1999

False Report of Sea of Marmara Eruption

Turkey

40.683°N, 29.1°E; summit elev. 0 m

All times are local (unless otherwise noted)


UFO adherent claims new volcano in Sea of Marmara

Following the Ms 7.8 earthquake in Turkey on 17 August (BGVN 24:08) an Email message originating in Turkey was circulated, claiming that volcanic activity was observed coincident with the earthquake and suggesting a new (magmatic) volcano in the Sea of Marmara. For reasons outlined below, and in the absence of further evidence, editors of the Bulletin consider this a false report.

The report stated that fishermen near the village of Cinarcik, at the E end of the Sea of Marmara "saw the sea turned red with fireballs" shortly after the onset of the earthquake. They later found dead fish that appeared "fried." Their nets were "burned" while under water and contained samples of rocks alleged to look "magmatic."

No samples of the fish were preserved. A tectonic scientist in Istanbul speculated that hot water released by the earthquake from the many hot springs along the coast in that area may have killed some fish (although they would be boiled rather than fried).

The phenomenon called earthquake lights could explain the "fireballs" reportedly seen by the fishermen. Such effects have been reasonably established associated with large earthquakes, although their origin remains poorly understood. In addition to deformation-triggered piezoelectric effects, earthquake lights have sometimes been explained as due to the release of methane gas in areas of mass wasting (even under water). Omlin and others (1999), for example, found gas hydrate and methane releases associated with mud volcanoes in coastal submarine environments.

The astronomer and author Thomas Gold (Gold, 1998) has a website (Gold, 2000) where he presents a series of alleged quotes from witnesses of earthquakes. We include three such quotes here (along with Gold's dates, attributions, and other comments):

(A) Lima, 30 March 1828. "Water in the bay 'hissed as if hot iron was immersed in it,' bubbles and dead fish rose to the surface, and the anchor chain of HMS Volage was partially fused while lying in the mud on the bottom." (Attributed to Bagnold, 1829; the anchor chain is reported to be on display in the London Navy Museum.)

(B) Romania, 10 November 1940. ". . . a thick layer like a translucid gas above the surface of the soil . . . irregular gas fires . . . flames in rhythm with the movements of the soil . . . flashes like lightning from the floor to the summit of Mt Tampa . . . flames issuing from rocks, which crumbled, with flashes also issuing from non-wooded mountainsides." (Phrases used in eyewitness accounts collected by Demetrescu and Petrescu, 1941).

(C) Sungpan-Pingwu (China), 16, 22, and 23 August 1976. "From March of 1976, various large anomalies were observed over a broad region. . . . At the Wanchia commune of Chungching County, outbursts of natural gas from rock fissures ignited and were difficult to extinguish even by dumping dirt over the fissures. . . . Chu Chieh Cho, of the Provincial Seismological Bureau, related personally seeing a fireball 75 km from the epicenter on the night of 21 July while in the company of three professional seismologists."

Yalciner and others (1999) made a study of coastal areas along the Sea of Marmara after the Izmet earthquake. They found evidence for one or more tsunamis with maximum runups of 2.0-2.5 m. Preliminary modeling of the earthquake's response failed to reproduce the observed runups; the areas of maximum runup instead appeared to correspond most closely with several local mass-failure events. This observation together with the magnitude of the earthquake, and bottom soundings from marine geophysical teams, suggested mass wasting may have been fairly common on the floor of the Sea of Marmara.

Despite a wide range of poorly understood, dramatic processes associated with earthquakes (Izmet 1999 apparently included), there remains little evidence for volcanism around the time of the earthquake. The nearest Holocene volcano lies ~200 km SW of the report location. Neither Turkish geologists nor scientists from other countries in Turkey to study the 17 August earthquake reported any volcanism. The report said the fisherman found "magmatic" rocks; it is unlikely they would be familiar with this term.

The motivation and credibility of the report's originator, Erol Erkmen, are unknown. Certainly, the difficulty in translating from Turkish to English may have caused some problems in understanding. Erkmen is associated with a website devoted to reporting UFO activity in Turkey. Photographs of a "magmatic rock" sample were sent to the Bulletin, but they only showed dark rocks photographed devoid of a scale on a featureless background. The rocks shown did not appear to be vesicular or glassy. What was most significant to Bulletin editors was the report author's progressive reluctance to provide samples or encourage follow-up investigation with local scientists. Without the collaboration of trained scientists on the scene this report cannot be validated.

References. Omlin, A, Damm, E., Mienert, J., and Lukas, D., 1999, In-situ detection of methane releases adjacent to gas hydrate fields on the Norwegian margin: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Yalciner, A.C., Borrero, J., Kukano, U., Watts, P., Synolakis, C. E., and Imamura, F., 1999, Field survey of 1999 Izmit tsunami and modeling effort of new tsunami generation mechanism: (Abstract) Fall AGU meeting 1999, Eos, American Geophysical Union.

Gold, T., 1998, The deep hot biosphere: Springer Verlag, 256 p., ISBN: 0387985468.

Gold, T., 2000, Eye-witness accounts of several major earthquakes (URL: http://www.people.cornell.edu/ pages/tg21/eyewit.html).

Information Contacts: Erol Erkmen, Tuvpo Project Alp.


Har-Togoo (Mongolia) — May 2003

Har-Togoo

Mongolia

48.831°N, 101.626°E; summit elev. 1675 m

All times are local (unless otherwise noted)


Fumaroles and minor seismicity since October 2002

In December 2002 information appeared in Mongolian and Russian newspapers and on national TV that a volcano in Central Mongolia, the Har-Togoo volcano, was producing white vapors and constant acoustic noise. Because of the potential hazard posed to two nearby settlements, mainly with regard to potential blocking of rivers, the Director of the Research Center of Astronomy and Geophysics of the Mongolian Academy of Sciences, Dr. Bekhtur, organized a scientific expedition to the volcano on 19-20 March 2003. The scientific team also included M. Ulziibat, seismologist from the same Research Center, M. Ganzorig, the Director of the Institute of Informatics, and A. Ivanov from the Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences.

Geological setting. The Miocene Har-Togoo shield volcano is situated on top of a vast volcanic plateau (figure 1). The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Pliocene and Quaternary volcanic rocks are also abundant in the vicinity of the Holocene volcanoes (Devyatkin and Smelov, 1979; Logatchev and others, 1982). Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Figure (see Caption) Figure 1. Photograph of the Har-Togoo volcano viewed from west, March 2003. Courtesy of Alexei Ivanov.

Observations during March 2003. The name of the volcano in the Mongolian language means "black-pot" and through questioning of the local inhabitants, it was learned that there is a local myth that a dragon lived in the volcano. The local inhabitants also mentioned that marmots, previously abundant in the area, began to migrate westwards five years ago; they are now practically absent from the area.

Acoustic noise and venting of colorless warm gas from a small hole near the summit were noticed in October 2002 by local residents. In December 2002, while snow lay on the ground, the hole was clearly visible to local visitors, and a second hole could be seen a few meters away; it is unclear whether or not white vapors were noticed on this occasion. During the inspection in March 2003 a third hole was seen. The second hole is located within a 3 x 3 m outcrop of cinder and pumice (figure 2) whereas the first and the third holes are located within massive basalts. When close to the holes, constant noise resembled a rapid river heard from afar. The second hole was covered with plastic sheeting fixed at the margins, but the plastic was blown off within 2-3 seconds. Gas from the second hole was sampled in a mechanically pumped glass sampler. Analysis by gas chromatography, performed a week later at the Institute of the Earth's Crust, showed that nitrogen and atmospheric air were the major constituents.

Figure (see Caption) Figure 2. Photograph of the second hole sampled at Har-Togoo, with hammer for scale, March 2003. Courtesy of Alexei Ivanov.

The temperature of the gas at the first, second, and third holes was +1.1, +1.4, and +2.7°C, respectively, while air temperature was -4.6 to -4.7°C (measured on 19 March 2003). Repeated measurements of the temperatures on the next day gave values of +1.1, +0.8, and -6.0°C at the first, second, and third holes, respectively. Air temperature was -9.4°C. To avoid bias due to direct heating from sunlight the measurements were performed under shadow. All measurements were done with Chechtemp2 digital thermometer with precision of ± 0.1°C and accuracy ± 0.3°C.

Inside the mouth of the first hole was 4-10-cm-thick ice with suspended gas bubbles (figure 5). The ice and snow were sampled in plastic bottles, melted, and tested for pH and Eh with digital meters. The pH-meter was calibrated by Horiba Ltd (Kyoto, Japan) standard solutions 4 and 7. Water from melted ice appeared to be slightly acidic (pH 6.52) in comparison to water of melted snow (pH 7.04). Both pH values were within neutral solution values. No prominent difference in Eh (108 and 117 for ice and snow, respectively) was revealed.

Two digital short-period three-component stations were installed on top of Har-Togoo, one 50 m from the degassing holes and one in a remote area on basement rocks, for monitoring during 19-20 March 2003. Every hour 1-3 microseismic events with magnitude <2 were recorded. All seismic events were virtually identical and resembled A-type volcano-tectonic earthquakes (figure 6). Arrival difference between S and P waves were around 0.06-0.3 seconds for the Har-Togoo station and 0.1-1.5 seconds for the remote station. Assuming that the Har-Togoo station was located in the epicentral zone, the events were located at ~1-3 km depth. Seismic episodes similar to volcanic tremors were also recorded (figure 3).

Figure (see Caption) Figure 3. Examples of an A-type volcano-tectonic earthquake and volcanic tremor episodes recorded at the Har-Togoo station on 19 March 2003. Courtesy of Alexei Ivanov.

Conclusions. The abnormal thermal and seismic activities could be the result of either hydrothermal or volcanic processes. This activity could have started in the fall of 2002 when they were directly observed for the first time, or possibly up to five years earlier when marmots started migrating from the area. Further studies are planned to investigate the cause of the fumarolic and seismic activities.

At the end of a second visit in early July, gas venting had stopped, but seismicity was continuing. In August there will be a workshop on Russian-Mongolian cooperation between Institutions of the Russian and Mongolian Academies of Sciences (held in Ulan-Bator, Mongolia), where the work being done on this volcano will be presented.

References. Devyatkin, E.V. and Smelov, S.B., 1979, Position of basalts in sequence of Cenozoic sediments of Mongolia: Izvestiya USSR Academy of Sciences, geological series, no. 1, p. 16-29. (In Russian).

Logatchev, N.A., Devyatkin, E.V., Malaeva, E.M., and others, 1982, Cenozoic deposits of Taryat basin and Chulutu river valley (Central Hangai): Izvestiya USSR Academy of Sciences, geological series, no. 8, p. 76-86. (In Russian).

Geologic Background. The Miocene Har-Togoo shield volcano, also known as Togoo Tologoy, is situated on top of a vast volcanic plateau. The 5,000-year-old Khorog (Horog) cone in the Taryatu-Chulutu volcanic field is located 135 km SW and the Quaternary Urun-Dush cone in the Khanuy Gol (Hanuy Gol) volcanic field is 95 km ENE. Analysis of seismic activity recorded by a network of seismic stations across Mongolia shows that earthquakes of magnitude 2-3.5 are scattered around the Har-Togoo volcano at a distance of 10-15 km.

Information Contacts: Alexei V. Ivanov, Institute of the Earth Crust SB, Russian Academy of Sciences, Irkutsk, Russia; Bekhtur andM. Ulziibat, Research Center of Astronomy and Geophysics, Mongolian Academy of Sciences, Ulan-Bator, Mongolia; M. Ganzorig, Institute of Informatics MAS, Ulan-Bator, Mongolia.


Elgon (Uganda) — December 2005

Elgon

Uganda

1.136°N, 34.559°E; summit elev. 3885 m

All times are local (unless otherwise noted)


False report of activity; confusion caused by burning dung in a lava tube

An eruption at Mount Elgon was mistakenly inferred when fumes escaped from this otherwise quiet volcano. The fumes were eventually traced to dung burning in a lava-tube cave. The cave is home to, or visited by, wildlife ranging from bats to elephants. Mt. Elgon (Ol Doinyo Ilgoon) is a stratovolcano on the SW margin of a 13 x 16 km caldera that straddles the Uganda-Kenya border 140 km NE of the N shore of Lake Victoria. No eruptions are known in the historical record or in the Holocene.

On 7 September 2004 the web site of the Kenyan newspaper The Daily Nation reported that villagers sighted and smelled noxious fumes from a cave on the flank of Mt. Elgon during August 2005. The villagers' concerns were taken quite seriously by both nations, to the extent that evacuation of nearby villages was considered.

The Daily Nation article added that shortly after the villagers' reports, Moses Masibo, Kenya's Western Province geology officer visited the cave, confirmed the villagers observations, and added that the temperature in the cave was 170°C. He recommended that nearby villagers move to safer locations. Masibo and Silas Simiyu of KenGens geothermal department collected ashes from the cave for testing.

Gerald Ernst reported on 19 September 2004 that he spoke with two local geologists involved with the Elgon crisis from the Geology Department of the University of Nairobi (Jiromo campus): Professor Nyambok and Zacharia Kuria (the former is a senior scientist who was unable to go in the field; the latter is a junior scientist who visited the site). According to Ernst their interpretation is that somebody set fire to bat guano in one of the caves. The fire was intense and probably explains the vigorous fuming, high temperatures, and suffocated animals. The event was also accompanied by emissions of gases with an ammonia odor. Ernst noted that this was not surprising considering the high nitrogen content of guano—ammonia is highly toxic and can also explain the animal deaths. The intense fumes initially caused substantial panic in the area.

It was Ernst's understanding that the authorities ordered evacuations while awaiting a report from local scientists, but that people returned before the report reached the authorities. The fire presumably prompted the response of local authorities who then urged the University geologists to analyze the situation. By the time geologists arrived, the fuming had ceased, or nearly so. The residue left by the fire and other observations led them to conclude that nothing remotely related to a volcanic eruption had occurred.

However, the incident emphasized the problem due to lack of a seismic station to monitor tectonic activity related to a local triple junction associated with the rift valley or volcanic seismicity. In response, one seismic station was moved from S Kenya to the area of Mt. Elgon so that local seismicity can be monitored in the future.

Information Contacts: Gerald Ernst, Univ. of Ghent, Krijgslaan 281/S8, B-9000, Belgium; Chris Newhall, USGS, Univ. of Washington, Dept. of Earth & Space Sciences, Box 351310, Seattle, WA 98195-1310, USA; The Daily Nation (URL: http://www.nationmedia.com/dailynation/); Uganda Tourist Board (URL: http://www.visituganda.com/).