Smithsonian / USGS Weekly Volcanic Activity Report

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday and averaging 16 reported volcanoes, this is not a comprehensive list of all eruptions this week, but rather a summary of activity that meet criteria discussed in the "Criteria and Disclaimers" section below.

Volcanic activity reported here is preliminary and subject to change. Carefully reviewed, detailed narratives over longer time periods are published as reports of the Bulletin of the Global Volcanism Network available through volcano profile pages.

Smithsonian / USGS Weekly Volcanic Activity Report for the week of 16 April-22 April 2003
Name	Location	Eruption Start Date	Report Status
Chikurachki	Paramushir Island (Russia)	—	New
Asamayama	Honshu (Japan)	—	Continuing
Guagua Pichincha	Ecuador	—	Continuing
Karangetang	Sangihe Islands	2018 Nov 25	Continuing
Karymsky	Eastern Kamchatka (Russia)	—	Continuing
Kilauea	Hawaiian Islands (USA)	—	Continuing
Klyuchevskoy	Central Kamchatka (Russia)	—	Continuing
Llaima	Central Chile	—	Continuing
Miyakejima	Izu Islands	—	Continuing
Popocatepetl	Mexico	2005 Jan 9	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Soufriere Hills	Montserrat	—	Continuing
Tungurahua	Ecuador	—	Continuing

All times are local unless otherwise stated.

Chikurachki | 16 April-22 April 2003 | New Activity / Unrest Cite this Report

Chikurachki
Paramushir Island (Russia)

Chikurachki stratovolcano, located on Paramushir Island in the Northern Kuriles, began erupting on 18 April 2003. During the next few days observers described the ash falls and substantial plumes with estimated heights up to ~10 km altitude. Observers on Paramushir island saw ash explosions on 18 April; ash fell in Podgorny town and Cape Vasiliev. Satellite data for 18 April revealed that ash plumes moved towards the SSE and traveled a distance of more than 50 km. The Aviation Meteorological Center at Yelizovo airport reported that on 19 April ash plumes rose 2,000 m. Three distinct eruptive events were detected in satellite data on 19 April, in one case ash plumes extended over 50 km SE.

The longest reported plume of the week occurred on 20 April; it reached over 250 km from the volcano towards the SE, later blowing E. Satellite analysts described a variety of plumes on 21 April: a narrow ash plume (visible ~130 km in length and trending SE), a comparatively wide ash plume (~ 25 km wide at a distance of ~50 km from the volcano), and some other ash plumes (over 50-70 km in length moving to the S). One reason why this eruption and its plumes are important is because they lie along a frequently traveled aviation route.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Asamayama | 16 April-22 April 2003 | Continuing ActivityCite this Report

Asamayama
Honshu (Japan)

JMA reported that Asama had four minor, brief (under 10-minute duration) eruptions thus far during 2003, the latest on 18 April when an ash cloud rose ~300 m. The first of the previous three occurred on 6 February when an ash cloud rose ~300 m and minor ash fell around the summit. The second took place on 30 March; again an ash cloud rose ~300 m and minor ash fell around the summit. The third took place on 7 April; in this case an ash cloud rose ~200 m. No unusual precursory seismic activity preceded these events. Asama lies in central Japan W of Tokyo, near the site of the 1998 Winter Olympic Games.

Source: Japan Meteorological Agency (JMA)

Guagua Pichincha | 16 April-22 April 2003 | Continuing ActivityCite this Report

Guagua Pichincha
Ecuador

The IG indicated that they detected seismic signals from a very minor Guagua Pichincha eruption on 17 April. The volcanologist on duty saw no visual signs of ash, implying that the seismic signals resulted from a very weak eruption with products confined to the summit crater. The IG also noted seeing similar seismic signals sporadically over the previous few days. The signals were thought to result from out-gassing, a class of behavior that if more energetic could generate larger ash clouds of impact to local residents and aviators. The IG also reported several volcano-tectonic earthquakes, seismic signals of rockfalls, and one long-period earthquake.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)

Karangetang | 16 April-22 April 2003 | Continuing ActivityCite this Report

Karangetang
Sangihe Islands

Karangetang's S crater gave off ash emissions that reached 250 m high during the week of 16-22 April. Just prior, on 15 April, an explosion that sounded like a blast was followed by lava avalanches traveling S and W and reaching ~1 km from their source at S crater. The resulting dark-gray ash column reached 1.5 km above the crater. Ash fell around Dame and Karalung villages, some fell into the sea on the E. Another similar explosion occurred on 20 April, but it generated a pyroclastic flow that extended 2.5 km in length. Blasting noises were audible for ~3 minutes. Seismic records suggested 32 explosion events, 226 multiphase earthquakes, and 26 emission earthquakes. Karangetang=s hazard status was at level 3 (out of a possible 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Karymsky | 16 April-22 April 2003 | Continuing ActivityCite this Report

Karymsky
Eastern Kamchatka (Russia)

Karymsky's eruptive vigor increased. Although seismicity stood at background levels during the past week and slightly above background levels on 14 April, ten=s of volcanic earthquakes per day began to be registered. Observations made on 16 April suggested the presence of fresh ash deposits extending to the ESE for a distance of over 10 km from the summit. Some data suggested that on 17 April an ash-and-gas plume rose 1,000 m above the crater (to ~2,500 m a.s.l.). These events caused authorities to raise the hazard status from Green to Yellow. A 23 April aviation notice described an apparent ash plume at ~3 km a.s.l. directed S.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), US Air Force Weather Agency

Kilauea | 16 April-22 April 2003 | Continuing ActivityCite this Report

Kilauea
Hawaiian Islands (USA)

During the week ending 22 April, Kilauea continued to erupt, sending lava down its SE flank either traveling over the land surface or through tubes. Lava entered the sea at the West Highcastle entry; activity there was sometimes weak, though one or more glowing areas were typically seen.

On 16 April a large tract of land not over-run by surrounding lava (a kipuka or ahu in the local parlance) remained within the Kohola lava flow, still ~30 cm above the top of inflated lavas that surround it. On the eastern margin of the swath of lava flows going down the steep slopes of Pulama pali, one partly crusted-over lava stream was highly visible. The crater of Pu`u `O`o was dark and obscured by fume. The previous day ended with a small inflation-deflation event recorded at both Kilauea's summit and Pu`u `O`o. These tilt changes began at Uwekahuna.

During 16-17 April, the Uwekahuna tiltmeter at Kilauea's summit recorded three small inflations, the last apparently right at its crest. Pu`u `O`o has generally followed suit, though in this case showing only two of the inflations very well. These tilts are not major but continue to illustrate the clear connection between Kilauea's summit, where most tilt events start, and Pu`u `O`o, 20 km away, where the tilt events follow a few minutes later.

Seismicity during the week was at low to normal levels. Instruments continued to register the summit swarm of long-period earthquakes and tremor, which began last June. Volcanic tremor at Pu`u `O`o remained elevated, as has been the norm for more than a week.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Klyuchevskoy | 16 April-22 April 2003 | Continuing ActivityCite this Report

Klyuchevskoy
Central Kamchatka (Russia)

A moderate vulcanian eruption of Kliuchevskoi began 15 April; it continued through at least 16 April. The eruption was preceded by above-background seismicity, and on 15 April there were ~70 earthquakes per day at ~30-km depth. Instruments registered continuous spasmodic volcanic tremor (up to 4.0 µm/second) and numerous weak shallow earthquakes. According to observers in Klyuchi, on 15 April a series of ash plumes rose up to 300 m above the crater and extended for 10 km. According to satellite data, on 16 April a thin, 175-km-long plume headed E. Observations on 17 April disclosed a zone of ash deposits extending ESE for 20 km from the crater. The Concern Color Code remained at Yellow.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Llaima | 16 April-22 April 2003 | Continuing ActivityCite this Report

Llaima
Central Chile

Llaima remained at Yellow alert at least through 16 April and eruptions began to contain significant tephra. Seismicity was almost 5-fold above background. Volcanologists expressed concern that the volcano=s glacial ice-cover could undergo local melting, which might lead to large and sudden outbursts of water (glacier bursts) down local drainages.

Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)

Miyakejima | 16 April-22 April 2003 | Continuing ActivityCite this Report

Miyakejima
Izu Islands

Miyake-jima has remained restless since its summer eruption in 2000, with robust degassing ongoing through the week of 16-22 April. The SO2 gas output (flux) remained high (about 5,000-10,000 tons/day) as of March 2003. All people who lived on Miyake-jima island have been evacuated since September 2000 and SO2 fluxes around that time had reached extremely high values, over 80,000 tons/day. Although high SO2 flux continues, thus far in 2003 there has been no eruption.

Source: Akihiko Tomiya, Senior Research Scientist, Geological Survey of Japan

Popocatepetl | 16 April-22 April 2003 | Continuing ActivityCite this Report

Popocatepetl
Mexico

The ongoing eruption at Popocatépetl was punctuated by a small explosion on 17 April, an event accompanied by incandescent fragments that reached 1 km E along the summit crater=s outer margin, and a modest ash plume directed toward the NE. Associated with the event, low-amplitude tremor persisted for about 2 hours, but no other significant geophysical changes were seen. More typical low-intensity outbursts also continued during the week, typically at rates of ten=s per day. The alert level still stood at Yellow, and the mountain road across the N flank remained open.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

Semeru | 16 April-22 April 2003 | Continuing ActivityCite this Report

Semeru
Eastern Java

During the week of 16-22 April, Semeru was continually active. A white-gray ash plume@ rose 400-500 m over the summit. Seismic signals interpreted as pyroclastic flows were recorded multiple times during the week. One pyroclastic flow on 18 April traveled into several local drainages, reaching lengths of ~2.5 and ~3.5 km.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Soufriere Hills | 16 April-22 April 2003 | Continuing ActivityCite this Report

Soufriere Hills
Montserrat

During 16-22 April, dome extrusion continued at Soufrière Hills. Poor visibility prevailed for parts of the week, but seismicity and SO2 fluxes remained significant. Numerous rockfalls and pyroclastic flows have occurred on the eastern flanks of the dome in the Tar River Valley. An observation flight indicated that rockfalls were beginning to spill southwards into the head of the White River. Observers noted that a very large spine had extruded on the dome=s summit. Despite frequent cloud cover during the week, satellite infrared sensors sometimes detected the thermal radiation from the dome, and other sensors continued to detect plumes from the volcano, typically tens of kilometers in length and blowing W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)

Tungurahua | 16 April-22 April 2003 | Continuing ActivityCite this Report

Tungurahua
Ecuador

Although activity was generally low during the week of 16-22 April, more volcanic explosions continued at Tungurahua. Many of these events were small, and minor vapor columns were also noted. Cloud cover obscured the volcano on some days. A 16 April aviation report discussed an ash cloud seen by IG rising up to ~7 km a.s.l. (~2 km above the summit). On 17 April two ash columns rose 1.5 and 2 km above the summit and blew SW and W, respectively. Although the volcano generally appeared relatively placid, there remained concern about sudden increases in eruptive output and about mudflows.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)

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Criteria & Disclaimers

Criteria

The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:

- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.

Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.

It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.

Disclaimers

1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are cover longer time periods and are more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.

2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.

3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.

4. Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.

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URL: https://volcano.si.edu/reports_weekly.cfm

Acronyms and Abbreviations

a.s.l. - above sea level

AVO - Alaska Volcano Observatory

AVHRR - Advanced Very High Resolution Radiometer

CENAPRED - Centro Nacionale de Prevencion de Desastres (México)

CONRED - Coordinadora Nacional para la Reducción de Desastres

COSPEC - Correlation Spectrometer

CVGHM (formerly VSI) - Center of Volcanology and Geological Hazard Mitigation

CVO - Cascades Volcano Observatory (USGS)

GMS - Geostationary Meteorological Satellite

GOES - Geostationary Operational Environmental Satellite

GVO - Goma Volcano Observatory

GVP - Global Volcanism Program (Smithsonian Institution)

HVO - Hawaiian Volcano Observatory (USGS)

ICE - Instituto Costarricense de Electricidad (Costa Rica)

IG - Instituto Geofísico (Ecuador)

IGNS - Institute of Geological and Nuclear Sciences (New Zealand) - now GNS Science

INETER - Instituto Nicaragüense de Estudios Territoriales (Nicaragua)

INGEMMET - Instituto Geológical Minero y Metalúrgico (Peru)

INGEOMINAS - Instituto Colombiano de Geología y Minería (Colombia)

INGV-CT - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (Italy)

INSIVUMEH - Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (Guatemala)

IRD - Institut de Recherche pour le Développement (France)

JMA - Japanese Meteorological Agency

KEMSD - Kamchatkan Experimental and Methodical Seismilogical Department

KVERT - Kamchatkan Volcanic Eruption Response Team

M - magnitude

METEOSAT - Meteorological Satellite

MEVO - Mount Erebus Volcano Observatory

MODIS - Moderate Resolution Imaging Spectroradiometer

MVO - Montserrat Volcano Observatory

MWO - Meteorological Watch Office

NEIC - National Earthquake Information Center

NIED - National Research Institute for Earth Science and Disaster Prevention (Japan)

NOAA - National Oceanic and Atmospheric Administration

NOTAM - Notice to Airmen

OVDAS - Observatorio Volcanologico de los Andes del Sur (Chile)

OFDA - Office of US Foreign Disaster Assistance

ONEMI - Oficina Nacional de Emergencia - Ministerio del Interior (Chile)

OVPDLF - Observatoire Volcanologique du Piton de la Fournaise (France)

OVSICORI-UNA - Observatorio Vulcanologico y Sismologico de Costa Rica, Universidad Nacional (Costa Rica)

PHIVOLCS - Philippine Institute of Volcanology and Seismology (Philippines)

RSAM - Real-time Seismic Amplitude Measurement

RVO - Rabaul Volcano Observatory

SERNAGEOMIN - Servicio Nacional de Geologia y Mineria (Chile)

SIGMET - Significant Meteorological Information

SNET - Servicio Nacional de Estudios Territoriales (El Salvador)

SVERT - Sakhalin Volcanic Eruption Response Team (Russia)

USAID - US Agency for International Development

USGS - United States Geological Survey

UTC - Coordinated Universal Time

VAAC - Volcanic Ash Advisory Center

VAFTAD - Volcanic Ash Forecast Transport And Dispersion

VDAP - Volcano Disaster Assistance Program (USGS)

VHP - Volcano Hazards Program (USGS)

VRC - Volcano Research Center (Japan)

Report for Chikurachki
Chikurachki stratovolcano, located on Paramushir Island in the Northern Kuriles, began erupting on 18 April 2003. During the next few days observers described the ash falls and substantial plumes with estimated heights up to ~10 km altitude. Observers on Paramushir island saw ash explosions on 18 April; ash fell in Podgorny town and Cape Vasiliev. Satellite data for 18 April revealed that ash plumes moved towards the SSE and traveled a distance of more than 50 km. The Aviation Meteorological Center at Yelizovo airport reported that on 19 April ash plumes rose 2,000 m. Three distinct eruptive events were detected in satellite data on 19 April, in one case ash plumes extended over 50 km SE.

The longest reported plume of the week occurred on 20 April; it reached over 250 km from the volcano towards the SE, later blowing E. Satellite analysts described a variety of plumes on 21 April: a narrow ash plume (visible ~130 km in length and trending SE), a comparatively wide ash plume (~ 25 km wide at a distance of ~50 km from the volcano), and some other ash plumes (over 50-70 km in length moving to the S). One reason why this eruption and its plumes are important is because they lie along a frequently traveled aviation route.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Report for Asamayama
JMA reported that Asama had four minor, brief (under 10-minute duration) eruptions thus far during 2003, the latest on 18 April when an ash cloud rose ~300 m. The first of the previous three occurred on 6 February when an ash cloud rose ~300 m and minor ash fell around the summit. The second took place on 30 March; again an ash cloud rose ~300 m and minor ash fell around the summit. The third took place on 7 April; in this case an ash cloud rose ~200 m. No unusual precursory seismic activity preceded these events. Asama lies in central Japan W of Tokyo, near the site of the 1998 Winter Olympic Games.
Source: Japan Meteorological Agency (JMA)

Report for Guagua Pichincha
The IG indicated that they detected seismic signals from a very minor Guagua Pichincha eruption on 17 April. The volcanologist on duty saw no visual signs of ash, implying that the seismic signals resulted from a very weak eruption with products confined to the summit crater. The IG also noted seeing similar seismic signals sporadically over the previous few days. The signals were thought to result from out-gassing, a class of behavior that if more energetic could generate larger ash clouds of impact to local residents and aviators. The IG also reported several volcano-tectonic earthquakes, seismic signals of rockfalls, and one long-period earthquake.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)

Report for Karangetang
Karangetang's S crater gave off ash emissions that reached 250 m high during the week of 16-22 April. Just prior, on 15 April, an explosion that sounded like a blast was followed by lava avalanches traveling S and W and reaching ~1 km from their source at S crater. The resulting dark-gray ash column reached 1.5 km above the crater. Ash fell around Dame and Karalung villages, some fell into the sea on the E. Another similar explosion occurred on 20 April, but it generated a pyroclastic flow that extended 2.5 km in length. Blasting noises were audible for ~3 minutes. Seismic records suggested 32 explosion events, 226 multiphase earthquakes, and 26 emission earthquakes. Karangetang=s hazard status was at level 3 (out of a possible 4).
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Karymsky
Karymsky's eruptive vigor increased. Although seismicity stood at background levels during the past week and slightly above background levels on 14 April, ten=s of volcanic earthquakes per day began to be registered. Observations made on 16 April suggested the presence of fresh ash deposits extending to the ESE for a distance of over 10 km from the summit. Some data suggested that on 17 April an ash-and-gas plume rose 1,000 m above the crater (to ~2,500 m a.s.l.). These events caused authorities to raise the hazard status from Green to Yellow. A 23 April aviation notice described an apparent ash plume at ~3 km a.s.l. directed S.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), US Air Force Weather Agency

Report for Kilauea
During the week ending 22 April, Kilauea continued to erupt, sending lava down its SE flank either traveling over the land surface or through tubes. Lava entered the sea at the West Highcastle entry; activity there was sometimes weak, though one or more glowing areas were typically seen.

On 16 April a large tract of land not over-run by surrounding lava (a kipuka or ahu in the local parlance) remained within the Kohola lava flow, still ~30 cm above the top of inflated lavas that surround it. On the eastern margin of the swath of lava flows going down the steep slopes of Pulama pali, one partly crusted-over lava stream was highly visible. The crater of Pu`u `O`o was dark and obscured by fume. The previous day ended with a small inflation-deflation event recorded at both Kilauea's summit and Pu`u `O`o. These tilt changes began at Uwekahuna.

During 16-17 April, the Uwekahuna tiltmeter at Kilauea's summit recorded three small inflations, the last apparently right at its crest. Pu`u `O`o has generally followed suit, though in this case showing only two of the inflations very well. These tilts are not major but continue to illustrate the clear connection between Kilauea's summit, where most tilt events start, and Pu`u `O`o, 20 km away, where the tilt events follow a few minutes later.

Seismicity during the week was at low to normal levels. Instruments continued to register the summit swarm of long-period earthquakes and tremor, which began last June. Volcanic tremor at Pu`u `O`o remained elevated, as has been the norm for more than a week.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Report for Klyuchevskoy
A moderate vulcanian eruption of Kliuchevskoi began 15 April; it continued through at least 16 April. The eruption was preceded by above-background seismicity, and on 15 April there were ~70 earthquakes per day at ~30-km depth. Instruments registered continuous spasmodic volcanic tremor (up to 4.0 µm/second) and numerous weak shallow earthquakes. According to observers in Klyuchi, on 15 April a series of ash plumes rose up to 300 m above the crater and extended for 10 km. According to satellite data, on 16 April a thin, 175-km-long plume headed E. Observations on 17 April disclosed a zone of ash deposits extending ESE for 20 km from the crater. The Concern Color Code remained at Yellow.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Report for Llaima
Llaima remained at Yellow alert at least through 16 April and eruptions began to contain significant tephra. Seismicity was almost 5-fold above background. Volcanologists expressed concern that the volcano=s glacial ice-cover could undergo local melting, which might lead to large and sudden outbursts of water (glacier bursts) down local drainages.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)

Report for Miyakejima
Miyake-jima has remained restless since its summer eruption in 2000, with robust degassing ongoing through the week of 16-22 April. The SO2 gas output (flux) remained high (about 5,000-10,000 tons/day) as of March 2003. All people who lived on Miyake-jima island have been evacuated since September 2000 and SO2 fluxes around that time had reached extremely high values, over 80,000 tons/day. Although high SO2 flux continues, thus far in 2003 there has been no eruption.
Source: Akihiko Tomiya, Senior Research Scientist, Geological Survey of Japan

Report for Popocatepetl
The ongoing eruption at Popocatépetl was punctuated by a small explosion on 17 April, an event accompanied by incandescent fragments that reached 1 km E along the summit crater=s outer margin, and a modest ash plume directed toward the NE. Associated with the event, low-amplitude tremor persisted for about 2 hours, but no other significant geophysical changes were seen. More typical low-intensity outbursts also continued during the week, typically at rates of ten=s per day. The alert level still stood at Yellow, and the mountain road across the N flank remained open.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

Report for Semeru
During the week of 16-22 April, Semeru was continually active. A white-gray ash plume@ rose 400-500 m over the summit. Seismic signals interpreted as pyroclastic flows were recorded multiple times during the week. One pyroclastic flow on 18 April traveled into several local drainages, reaching lengths of ~2.5 and ~3.5 km.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Soufriere Hills
During 16-22 April, dome extrusion continued at Soufrière Hills. Poor visibility prevailed for parts of the week, but seismicity and SO2 fluxes remained significant. Numerous rockfalls and pyroclastic flows have occurred on the eastern flanks of the dome in the Tar River Valley. An observation flight indicated that rockfalls were beginning to spill southwards into the head of the White River. Observers noted that a very large spine had extruded on the dome=s summit. Despite frequent cloud cover during the week, satellite infrared sensors sometimes detected the thermal radiation from the dome, and other sensors continued to detect plumes from the volcano, typically tens of kilometers in length and blowing W.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)

Report for Tungurahua
Although activity was generally low during the week of 16-22 April, more volcanic explosions continued at Tungurahua. Many of these events were small, and minor vapor columns were also noted. Cloud cover obscured the volcano on some days. A 16 April aviation report discussed an ash cloud seen by IG rising up to ~7 km a.s.l. (~2 km above the summit). On 17 April two ash columns rose 1.5 and 2 km above the summit and blew SW and W, respectively. Although the volcano generally appeared relatively placid, there remained concern about sudden increases in eruptive output and about mudflows.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)