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.

 Scientific Event Alert Network Bulletin - Volume 05, Number 08 (August 1980)


Managing Editor: David Squires

Aira (Japan)

More frequent explosions

Arenal (Costa Rica)

Lava extrusion continues

Bulusan (Philippines)

Explosions and seismicity continue

Etna (Italy)

Two one-day eruptions

Gamalama (Indonesia)

Strong tephra eruption; 40,000 evacuate

Gareloi (United States)

Tephra cloud from summit crater

Hekla (Iceland)

Large tephra cloud and lava flows

Karkar (Papua New Guinea)

Gas emission strengthens

Kilauea (United States)

Intrusion into the upper east rift zone

Krafla (Iceland)

Inflation resumes after last month's eruption

Langila (Papua New Guinea)

Occasional tephra emission

Malinao (Philippines)

Small phreatic explosion

Manam (Papua New Guinea)

Ash emission continues

Mayon (Philippines)

Harmonic tremor

St. Helens (United States)

One small explosion; lava dome growth stops

White Island (New Zealand)

Ash eruption



Aira (Japan) — August 1980 Citation iconCite this Report

Aira

Japan

31.593°N, 130.657°E; summit elev. 1117 m

All times are local (unless otherwise noted)


More frequent explosions

The number of recorded explosions increased from 16 in July to 34 in August. The highest August eruption cloud rose 2 km above the summit, on the 2nd. Ash frequently fell NE of the volcano but no damage was reported. . . .

Geologic Background. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Information Contacts: JMA, Tokyo.


Arenal (Costa Rica) — August 1980 Citation iconCite this Report

Arenal

Costa Rica

10.463°N, 84.703°W; summit elev. 1670 m

All times are local (unless otherwise noted)


Lava extrusion continues

The following is from the Institute of Volcanology, Boletín de Vulcanología, no. 8.

The block lava flow extruded from the W end of the elliptical summit crater since mid-1979 continued to descend the SW flank through April, causing small forest fires. During a period of increased extrusion in February, the lava had overflowed its channel at about 1,200 m elevation and divided into seven subflows, partially covering three earlier flow deposits.

In early May, lava from the same vent began moving down the W flank. This flow, ~60 m wide and 20 m thick, reached the N rim of Crater A (~1,100 m elevation) by early July. An arm of the flow at 900 m elevation was still advancing on 10 July, although feeding from the vent had stopped.

Another flow, the 33rd since nearly continuous extrusion of block lava began in 1968, started to descend the NW flank in early July. On 11 July its front was at ~1,200 m elevation and was continuing to advance.

Further References. Guendel, F. and Malavassi, E., 1980, La actividad del volcán Arenal entre los días 15 al 20 de Agosto de 1980: Boletín de Vulcanología, no. 9, p. 3-4.

Wadge, G., 1983, The magma budget of Volcán Arenal, Costa Rica from 1968-1980: JVGR, v. 19, p. 281-302.

Geologic Background. Conical Volcán Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1670-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. Arenal lies along a volcanic chain that has migrated to the NW from the late-Pleistocene Los Perdidos lava domes through the Pleistocene-to-Holocene Chato volcano, which contains a 500-m-wide, lake-filled summit crater. The earliest known eruptions of Arenal took place about 7000 years ago, and it was active concurrently with Cerro Chato until the activity of Chato ended about 3500 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. An eruptive period that began with a major explosive eruption in 1968 ended in December 2010; continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows characterized the eruption from vents at the summit and on the upper western flank.

Information Contacts: J. Barquero H., Univ. Nacional, Heredia.


Bulusan (Philippines) — August 1980 Citation iconCite this Report

Bulusan

Philippines

12.769°N, 124.056°E; summit elev. 1535 m

All times are local (unless otherwise noted)


Explosions and seismicity continue

Occasional explosions continued through late August. Four explosions have occurred since last month, on 30 July (the strongest) and 1, 5, and 24 August. Ash-laden steam clouds rose 4-7 km above the summit, depositing ash as much as 14 km from the crater. The maximum measured ashfall thickness was 3.5 mm. The explosions were preceded by earthquakes of intensities I-IV on the MRF scale, continuing the seismicity that began on 6 July. As of 28 August, occasional felt events were continuing.

Geologic Background. Luzon's southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. It lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded since the mid-19th century.

Information Contacts: O. Peña, COMVOL, Quezon City.


Etna (Italy) — August 1980 Citation iconCite this Report

Etna

Italy

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

All times are local (unless otherwise noted)


Two one-day eruptions

Relatively weak activity similar to that of late July continued through August at Etna. A 1-day eruption on 1 September deposited ash on the E flank and extruded two lava flows.

John Guest climbed the volcano on 18 August. As on 31 July, explosions occurred deep within Bocca Nuova. The Chasm remained quiet. Mild strombolian activity continued from the Southeast Crater, but reportedly weakened the following week. Romolo Romano reported that a swarm of local seismic events began on 21 August.

At 0957 on 1 September, a pale brown plume was seen rising from the Northeast Crater, which last erupted in March 1978 (03:05). By 1130, explosions were ejecting large bombs or blocks every 10-15 minutes. An increase in seismicity at about 1700 was followed at 1730 by stronger explosions that were audible in Fornazzo, 10 km E of the crater. A large black eruption column rose to 6 km above the crater. By 1800, ash was falling on Fornazzo and the entire E flank. Geologists reached the eruption area by about 2000 and saw nearly continuous strombolian explosions from two vents in the Northeast Crater ejecting tephra to 500-600 m above the rim. Lava from the Northeast Crater flowed to the N and NW. By the next morning, the eruption had stopped. Heavy fog made mapping of the two lava flows difficult, but the NW flow had moved past Punta Lucia, about 3/4 km from the Northeast Crater.

A second brief eruption from the Northeast Crater began early 6 September, ending at about 1500 the same day, after an estimated 10 hours of activity. A small lava flow was extruded. No further information was available at press time.

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: J. Guest and C. Kilburn, Univ. of London; T. Sanderson, Imperial College; R. Romano, IIV; G. Kieffer, Univ. de Clermont-Ferrand.


Gamalama (Indonesia) — August 1980 Citation iconCite this Report

Gamalama

Indonesia

0.8°N, 127.33°E; summit elev. 1715 m

All times are local (unless otherwise noted)


Strong tephra eruption; 40,000 evacuate

An incandescent tephra eruption from the central crater began with an explosion on 4 September at 1430, followed by a second ~ 2 hours later, and others at 0030, 0330, and 1120 the next day. Incandescent material fell 500-750 m from the crater, starting brush and forest fires. Ash fell on the entire island, accumulating to a depth of 10 cm by the second day of the eruption at Ternate City, 7-8 km E of the crater. Ash thicknesses reached 15 cm on some parts of the island, according to AFP.

Two earthquakes were felt by persons remaining on the island on 6 September as the eruption continued. By 7 September, activity had declined. Ash clouds rose ~ 1 km and were blown N by the prevailing wind, keeping ash away from the S half of the island, including Ternate City.

About 40,000 of the approximately 60,000 residents fled Ternate Island for Tidore Island, 5 km to the S, during the first two days of the eruption. No casualties have occurred according to the VSI, AFP, and Reuters, although some of the broadcast press apparently incorrectly reported casualties. A hazard map previously prepared by VSI delineates a danger zone of 33 km2 (population 2,500) in the summit area and an alert zone of 30 km2 on the N, NW, and NE flanks (population 2,500). The S and E parts of the island are considered to be safe by VSI.

Geologic Background. Gamalama is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera, and is one of Indonesia's most active volcanoes. The island was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the thorough documentation of Gamalama's historical activity. Three cones, progressively younger to the north, form the summit. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano. Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.

Information Contacts: A. Sudradjat, VSI; AFP; Reuters.


Gareloi (United States) — August 1980 Citation iconCite this Report

Gareloi

United States

51.79°N, 178.794°W; summit elev. 1573 m

All times are local (unless otherwise noted)


Tephra cloud from summit crater

During an overflight on 8 August, USN pilot Edwin Beech saw vapor rising to about 1 km above the summit crater. The next day, a Northwest Orient Airlines pilot observed a steam and ash column that reached 10.5 km altitude and was blown NNW, away from inhabited areas. Poor weather obscured the summit for the next several days, although large eruption columns would have been visible above the cloud layer from passing aircraft.

On 13 August, USN pilots were able to see the top 300 m of the volcano. A light gray eruption cloud that appeared to originate from the NE quadrant of the summit crater rose to about 2.5 km altitude (1 km above the summit), depositing ash to the NW. Both Lt. Beech and David Evans, who operates the USGS seismic station on nearby Adak Island, felt that the summit area had changed significantly during the eruption.

By 23-24 August, the activity had declined to weak vapor emission. No lava flows have been observed. Gareloi's last reported eruption was in January 1952.

Geologic Background. The 8 x 10 km Gareloi Island, the northernmost volcano of the Delarof Group at the western end of the Andreanof Islands, consists of a stratovolcano with two summits and a prominent SE-trending fissure. The fissure was formed during an eruption in 1929 and extends from the southern summit to the sea. Steep sea cliffs that are cut into rocks of an older, eroded center are found on the SW coast, and submarine deposits of three debris avalanches produced by edifice collapse are found offshore. Young lava flows cover the older volcano from the summit to the coast along three broad axes trending NW, ENE, and S. The 1929 eruption originated from 13 craters along a 4-km-long fissure. Phreatic explosions were followed by the ejection of glassy pumice, lapilli, scoria, and older blocks, as well as by the emission of four short, steep lava flows, one of which reached the SE coast.

Information Contacts: T. Miller, USGS, Anchorage; Lt. E. Beech, U.S. Navy, Adak Island; D. Evans, USGS, Adak Island.


Hekla (Iceland) — August 1980 Citation iconCite this Report

Hekla

Iceland

63.983°N, 19.666°W; summit elev. 1490 m

All times are local (unless otherwise noted)


Large tephra cloud and lava flows

"Hekla started erupting at 1328 on 17 August. Small earthquakes were recorded on local seismographs for 20-25 minutes prior to the first explosions but these precursors were not noticed until later.

"This was a mixed eruption starting in the summit area and quickly extending to the full fissure length of 7 km, longer than observed in the 1947 and 1970 eruptions. The initial activity at 1320 was a steam column, then a dark tephra column started between 1327 and 1330. The main tephra fall lasted about 2 hours and extended NNE, and the eruption column reached about 15 km altitude. The maximum tephra thickness 10 km N of the summit was 20 cm, and at the N coast, about 230 km distant, 1 mm or less. The fluorine content in many grazing districts is above danger level, causing problems for livestock, especially sheep. Lava began flowing shortly after the beginning of the eruption. The first flows appeared near the summit, then lava eruption extended to the lower parts of the fissure. Most of the lava issued within 12 hours and nearly all within 24 hours, forming four main separate lava flows, covering an area of about 22 km2. The volume of the lava is estimated at about 0.1 km2 and the tephra somewhat less than in the 1970 eruption, which produced 0.07 km3.

"Glowing scoria was last observed in the early morning of 20 August. Steam emission was continuing as of late August. For the first few days following the eruption this steam column was often darkened at the base, but no glow was observed.

"Preliminary chemical analyses of tephra and lava show composition similar to that of the 1970 eruption products. The last Hekla eruption took place 5 May-5 July 1970, making this period of quiescence of only 10 years the shortest recorded for Hekla since 1104. The shortest previous period between eruptions was 1206-22 and the second shortest was between the 1947 and 1970 eruptions. If the present eruption episode is over now, the behavior is highly unusual. All previous known eruptions have lasted from 2 months to 2 years. Initially there have been a few days of major activity, followed by a few almost quiet days, then renewed explosive activity and lava eruption concentrated on small parts of the fissure."

Geologic Background. One of Iceland's most prominent and active volcanoes, Hekla lies near the southern end of the eastern rift zone. Hekla occupies a rift-transform junction, and has produced basaltic andesites, in contrast to the tholeiitic basalts typical of Icelandic rift zone volcanoes. Vatnafjöll, a 40-km-long, 9-km-wide group of basaltic fissures and crater rows immediately SE of Hekla forms a part of the Hekla-Vatnafjöll volcanic system. A 5.5-km-long fissure, Heklugjá, cuts across the 1491-m-high Hekla volcano and is often active along its full length during major eruptions. Repeated eruptions along this rift, which is oblique to most rifting structures in the eastern volcanic zone, are responsible for Hekla's elongated ENE-WSW profile. Frequent large silicic explosive eruptions during historical time have deposited tephra throughout Iceland, providing valuable time markers used to date eruptions from other Icelandic volcanoes. Hekla tephras are generally rich in fluorine and are consequently very hazardous to grazing animals. Extensive lava flows from historical eruptions, which date back to 1104 CE, cover much of the volcano's flanks.

Information Contacts: K. Grönvold, Nordic Volcanological Institute (NVI); S. Thorarinsson, Univ. of Iceland.


Karkar (Papua New Guinea) — August 1980 Citation iconCite this Report

Karkar

Papua New Guinea

4.649°S, 145.964°E; summit elev. 1839 m

All times are local (unless otherwise noted)


Gas emission strengthens

"White vapour continued to be emitted from summit sources. An aerial inspection on 12 August, and aerial and ground inspections on the 14th and 15th, revealed copious white vapour emissions from the E side of Bagiai Cone and from sources on the E part of the caldera floor. These sources are believed to be stronger than they were at the time of the previous inspections (May 1980). Conditions inside the 1979 crater were similar to those in May. A descent was made into the crater and its depth was measured at 150 m. Silting of the crater floor has resulted in a flat floor consisting of coarse sandy sediment and some small boulders. Ejections of dark, sediment-rich water to heights of about 0.4 m were taking place over the entire surface of a pool of water at the centre of the crater floor. Vigorous gas ebullition was occurring from the muddy area immediately surrounding the pool. Numerous fumaroles on the E wall of the crater released vapour under low pressure. No unusual seismic activity was recorded in August and the intensity of the seismicity was unchanged."

Geologic Background. Karkar is a 19 x 25 km wide, forest-covered island that is truncated by two nested summit calderas. The 5.5-km-wide outer caldera was formed during one or more eruptions, the last of which occurred 9000 years ago. The eccentric 3.2-km-wide inner caldera was formed sometime between 1500 and 800 years ago. Parasitic cones are present on the N and S flanks of this basaltic-to-andesitic volcano; a linear array of small cones extends from the northern rim of the outer caldera nearly to the coast. Most historical eruptions, which date back to 1643, have originated from Bagiai cone, a pyroclastic cone constructed within the steep-walled, 300-m-deep inner caldera. The floor of the caldera is covered by young, mostly unvegetated andesitic lava flows.

Information Contacts: C. McKee, RVO.


Kilauea (United States) — August 1980 Citation iconCite this Report

Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


Intrusion into the upper east rift zone

Magma was intruded into the upper E rift zone on 27 August, the first intrusive activity there since March. As in the two March intrusions, no eruption took place. An earthquake swarm began near Puhimau Crater (about 1.5 km SE of the caldera rim) at 1425 on 27 August. Within 6 minutes, the number of microearthquakes had increased to several per minute. Summit deflation started 30 minutes after the swarm, at 1455.

The earthquakes migrated generally downrift at about 1 km/hour. Several were felt nearby, with the three highest magnitudes ranging from 3.6 to 4.0. Hundreds of magnitude 1-3 events occurred at depths of 1-4 km. The seismographs closest to the swarm apparently registered some shallow volcanic tremor, but microearthquakes occurred so rapidly that tremor was obscured on the records. The number of microearthquakes per minute started to decrease at about 1830 and the swarm ended early the next morning. Summit deflation had stopped at about 1930 on 27 August, after 7.5 µrad of tilt had been recorded.

The USGS interpreted the activity as the formation of a dike estimated to be about 3 km long, 1-2 km high, and l m wide, located 1-3 km beneath the surface. About 4 x 106 m3 of magma were calculated to have been injected into the dike between 1500 and 1930 on 27 August.

SO2 emission was detected in the Puhimau thermal area (where the earthquake swarm began) on 28 August. The CO2/SO2 ratios of gases emitted by the summit fumaroles before and after the intrusion remained about the same as the previous week.

Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.

Information Contacts: Hawaiian Volcano Observatory, USGS.


Krafla (Iceland) — August 1980 Citation iconCite this Report

Krafla

Iceland

65.715°N, 16.728°W; summit elev. 800 m

All times are local (unless otherwise noted)


Inflation resumes after last month's eruption

"Inflation of the magma reservoirs at Krafla, as monitored by ground movement, continues. At present,inflation is occurring at about the rate measured at similar ground levels during previous inflation periods, suggesting that the rate of magma supply remains similar. About 70% of the July deflation has now been recovered and the previous maximum ground level is likely to be reached after mid-October."

Geologic Background. The Krafla central volcano, located NE of Myvatn lake, is a topographically indistinct 10-km-wide caldera that is cut by a N-S-trending fissure system. Eruption of a rhyolitic welded tuff about 100,000 years ago was associated with formation of the caldera. Krafla has been the source of many rifting and eruptive events during the Holocene, including two in historical time, during 1724-29 and 1975-84. The prominent Hverfjall and Ludent tuff rings east of Myvatn were erupted along the 100-km-long fissure system, which extends as far as the north coast of Iceland. Iceland's renowned Myvatn lake formed during the eruption of the older Laxarhraun lava flow from the Ketildyngja shield volcano of the Fremrinamur volcanic system about 3800 years before present (BP); its present shape is constrained by the roughly 2000 years BP younger Laxarhraun lava flow from the Krafla volcanic system. The abundant pseudocraters that form a prominent part of the Myvatn landscape were created when the younger Laxarhraun lava flow entered the lake.

Information Contacts: K. Grönvold, NVI.


Langila (Papua New Guinea) — August 1980 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)


Occasional tephra emission

"The eruption continued at the same intensity in August. Emissions from the active vent in Crater 3 were mostly white and blue, but during a more active phase at mid-month grey emissions were observed. Lava fragment ejections and glows were observed on four consecutive nights 14-17 August. Rumbling and explosion sounds were heard on most days during the month. Crater 2 usually emitted white vapor, but on four occasions in the first half of August, brown emissions were observed. Glow at Crater 2 was observed on 4 August. The level and character of seismic activity was unchanged."

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: C. McKee, RVO.


Malinao (Philippines) — August 1980 Citation iconCite this Report

Malinao

Philippines

13.416°N, 123.608°E; summit elev. 1548 m

All times are local (unless otherwise noted)


Small phreatic explosion

A small phreatic explosion took place on 29 July from one of the pools of hot water in the Naglagbong thermal area, Tiwi geothermal field, at the E foot of Malinao. The explosion ejected hot mud and blocks up to 2/3 m in diameter. The ejecta reached heights of 150 m and fell as much as 350 m from the vent. One person received second-degree burns and two buildings were damaged, one a COMVOL seismic station.

Before the explosion the pool was 15 m in diameter and 4.3 m deep, with clear emerald-green water at a temperature of 85°C. As early as 6 July, the seismograph recorded unusual microseisms. Two hours before the explosion, geysering of muddy water was observed.

[The minor explosion from the Naglabong thermal area that ejected blocks in 1980 was probably due to water drawdown during development of the Tiwi geothermal field (Newhall, 1994, pers. comm.).]

Geologic Background. Forested Malinao stratovolcano, NNW of Mayon, contains a large summit crater that is breached to the east. This Quaternary volcano, also known as Buhi or Takit, was active from about 500,000 to 60,000 years ago (Nielson et al., 1996), but the E flank is the site of Luzon's largest solfataras and hot springs, some of which deposit silicious sinter. A minor explosion from the Naglabong thermal area that ejected blocks in 1980 was probably due to water drawdown during development of the Tiwi geothermal field (Newhall 1994, pers. comm.).

Information Contacts: O. Peña, COMVOL, Quezon City.


Manam (Papua New Guinea) — August 1980 Citation iconCite this Report

Manam

Papua New Guinea

4.08°S, 145.037°E; summit elev. 1807 m

All times are local (unless otherwise noted)


Ash emission continues

"Activity during August continued at the same level as that of June and July. Emissions from Southern crater were mostly white vapour and brown ash, but grey ash emissions were observed on 20 August and blue vapours were occasionally seen. Roaring and rumbling sounds were associated with stronger pulses of ash emission. Main crater was obscured most of the time, but on several occasions white vapour emissions were observed. Brown ash emissions from Main crater were observed on 20 August. No crater glows or lava fragment ejections were observed from either crater. Seismicity and tilt remained steady."

Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: C. McKee, RVO.


Mayon (Philippines) — August 1980 Citation iconCite this Report

Mayon

Philippines

13.257°N, 123.685°E; summit elev. 2462 m

All times are local (unless otherwise noted)


Harmonic tremor

Short-duration harmonic tremor began to be recorded at Mayon on 16 August. Bursts of tremor continued, but have become less frequent since the 16th. Similar seismicity preceded the 1978 eruption and accompanied crater glow in July 1979.

Geologic Background. Beautifully symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The structurally simple edifice has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions date back to 1616 and range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Information Contacts: O. Peña, COMVOL, Quezon City.


St. Helens (United States) — August 1980 Citation iconCite this Report

St. Helens

United States

46.2°N, 122.18°W; summit elev. 2549 m

All times are local (unless otherwise noted)


One small explosion; lava dome growth stops

USGS personnel measured temperatures in the 7 August pyroclastic-flow deposits of 647°C near the crater and 639°C near their distal margin the day after emplacement. By 8 August a lava dome had filled the inner crater formed during the 22 July explosions to about half its former depth of almost 100 m. More than 20 m of additional dome growth had taken place by the morning of 9 August. Occasional bursts of vapor and ash rose to 3-6 km altitude on 8 August, accompanied by small seismic events. SO2 emission increased from about 900 t/d on 8 August to at least 2,000 t/d on the 9th, but explosive bursts had ended and seismic activity was very low.

During the next several days, the rates of CO2 and SO2 emission fluctuated substantially (table 1). The dome appeared to have risen slightly between 9 and 11 August, but no growth has been observed since. The deformation monitoring line between the crater and a ridge W of Spirit Lake shortened about 3 cm/day from 8-13 August, a rate typical of previous inter-eruption periods since measurements resumed in mid-June. No significant changes in ground tilt around the base of the volcano have been recorded since June.

Table 1. Daily rates of CO2 and SO2 emissions from Mt. St. Helens during 10-29 August, measured in t/d by remote sensing equipment. No data are available for 18, 27, and 28 August. Data for 15 August does not include gas released by the explosion.

Date CO2 SO2 CO2/SO2
10 Aug 1980 3,100 600 5.2
11 Aug 1980 5,100 900 5.4
12 Aug 1980 2,100 650 3.2
13 Aug 1980 19,000 3,400 5.6
14 Aug 1980 8,700 1,600 5.4
15 Aug 1980 2,400 800 3.2
16 Aug 1980 less than 3,000 ~1,000 less than 3.0
17 Aug 1980 4,200 1,500 2.8
18 Aug 1980 -- -- --
19 Aug 1980 3,700 1,300 2.8
20 Aug 1980 3,300 1,900 1.7
21 Aug 1980 6,900 2,600 2.7
22 Aug 1980 11,000 2,000 5.5
23 Aug 1980 5,500 1,800 3.1
24 Aug 1980 6,800 1,250 5.4
25 Aug 1980 2,100 520 4.0
26 Aug 1980 3,900 1,400 2.8
27 Aug 1980 -- -- --
28 Aug 1980 -- -- --
29 Aug 1980 6,000 1,000 6.0

On 15 August at 1437, an ash-rich cloud rose to about 1 km above the volcano. The cloud became gradually less ash-laden, and dissipated after less than 15 minutes. Volcanic tremor was recorded during the eruption, declining as the eruption waned, but there was no premonitory seismicity. The activity blasted a small crater in the W side of the dome but did not destroy it. A similar eruption had occurred 28 July.

The surface of the lava dome was about 7 m lower on 17 August than it had been before the 15 August explosion. No shortening of the deformation monitoring line occurred between 13 and 17 August, but shortening resumed 19 August, indicating renewed inflation. Seismicity was limited to infrequent very small shallow events, many of which probably represented rockfalls in the crater.

On 22 August, a small quantity of water from Maratta Creek, a tributary of the North Fork of the Toutle River, breached a portion of the nearly 30 km-long debris dam left in the Toutle by the 18 May eruption. Water and debris flowed about 3 km downstream where it formed a small lake with an estimated volume of 3.8 x 105 m3. Five days later this lake overflowed, moving nearly 10 km down the Toutle valley to Camp Baker, site of a partially completed dam project designed to control the much larger floods that could occur in the debris-clogged valley when heavy rains resume in the autumn.

Some equipment was damaged at the construction site. Much of the water was contained by the unfinished check dam, but some continued about 15 km farther to the town of Toutle, damaging or destroying some temporary bridges and access roads. No casualties were reported.

Mt. St. Helens remained quiet through early September. Gas emission continued to fluctuate but no explosions occurred. Deformation monitoring lines began to lengthen slightly on 25 August, indicating slight deflation of the volcano, but an average of 2 cm/day of contraction by early September showed a return to more typical gradual inflation. On 30 August, the lava dome was the same size as on 9 August. Incandescence could be seen through deep cracks in its surface and through the small crater formed by the 15 August explosion. Cracks in the walls and floor of the inner crater containing the dome also revealed incandescent material. Seismicity remained generally weak in late August and early September. A brief earthquake swarm on 4 September began with a M 2.5 event at 2046, followed by four shocks within the next 9 minutes. All were centered 2-4 km beneath an area about 8 km NNW of Mt. St. Helens and were believed by the USGS to be of tectonic origin.

Monitoring of material ejected into the stratosphere by the 18 May eruption continues. Results from NASA's lidar at Wallops Island, Virginia show that the layer at 18 km had become more diffuse by August, occupying a zone between 16 and 20 km. In Tucson, Arizona, Aden and Marjorie Meinel continued to observe a weak layer at this altitude during August sunrises and sunsets. A NASA P-3 aircraft will collect data on the 18 May material during a mid-September cross-country flight, timed to coincide with information-gathering by NASA's SAGE satellite as it passes over the Northern Hemisphere.

Two reports in the 5 September issue of Science present data on the petrology, chemistry, and size distribution of the 18 May tephra. Hooper and others emphasize the bimodal character of ash deposited about 400 km ENE of Mt. St. Helens. The ash changed abruptly from a relatively dark, glass-poor silicic andesite to a lighter-colored glass-rich rhyodacite 3.25-3.5 hours after ashfall began. This interval corresponds quite closely to the timing of changes observed in the character of the eruption column at the volcano SEAN 05:05). Fruchter and others present bulk analyses of ash collected at numerous locations in Washington. In addition to petrology and major and trace element chemical analyses, the report focuses on the tephra's toxic and radioactive components, which do not appear to have been abundant enough to have a significant effect on animal or plant life.

The July 1980 issue of the Washington Geologic Newsletter lists Mt. St. Helens research projects being carried out by 25 groups at 20 institutions and government agencies, in addition to giving sources for pre- and post-eruption maps and airphotos of the volcano. In addition, names and addresses of USGS personnel with the particular Mt. St. Helens study on which each was working as of 20 June are listed. An eruption chronology, and reports on ashfall distribution and petrography are also presented in this publication.

Pre- and post- 18 May photographs and satellite images of Mt. St. Helens and vicinity are available from the EROS Data Center, Sioux Falls SD 57198. Among these are about 1,500 photographs taken by USGS personnel in low-altitude aircraft; color infrared photographs taken at 18 km altitude from NASA's U-2 aircraft on 1 May and 19 June; and cloud-free LANDSAT images.

Geologic Background. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago and has been the most active volcano in the Cascade Range during the Holocene. Prior to 2200 years ago, tephra, lava domes, and pyroclastic flows were erupted, forming the older St. Helens edifice, but few lava flows extended beyond the base of the volcano. The modern edifice was constructed during the last 2200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the north flank, and were witnessed by early settlers.

Information Contacts: D. Peterson, USGS, Vancouver, WA; R.Tilling, USGS, Reston, VA; S. Malone, R. Crosson, E. Endo, University of Washington; M.P. McCormick, NASA Langley Research Center; A. and M. Meinel, University of Arizona; UPI.


White Island (New Zealand) — August 1980 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)


Ash eruption

On 19 July, residents of Whakatane observed a black ash column that rose about 3 km above the volcano. However, a 28 July NZGS overflight found it little changed from 13 June. The island was covered by red-gray ash, deeply gullied in places on the crater floor. Partly eroded impact craters extended up to 200 m from the SE rim of 1978 Crater. The latter was hidden by voluminous clouds of white steam and gas while the recently formed subsidiary gas vents to the E (05:02) were obscured by vapor from adjacent fumaroles. Other fumarolic activity farther to the N appeared to have declined since the previous inspection. The sea immediately off the NW coast was colored white, probably due to suspension of sulphur (and other precipitates from underwater hot springs; 5:05).

Seismicity during July was characterized by relatively low tremor levels and occasional earthquakes, some of low frequency (B-type). Periods of high-amplitude, high-frequency tremor were recorded 11-16 July. Some larger, high-frequency, probably A-type or regional earthquakes were recorded on 27 July. The seismograph was not operational during the 19 July eruption.

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: I. Nairn, NZGS, Rotorua.

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 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.

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 Special Announcements


Special announcements of various kinds and obituaries.

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 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 (SEAN 22:08) False Report of Mount Pinokis Eruption

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

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

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

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

UFO adherent claims new volcano in Sea of Marmara

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

Fumaroles and minor seismicity since October 2002

12/2005 (SEAN 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/).