All times are local unless otherwise stated.

Marapi | 25 April-1 May 2001 | New Activity / UnrestCite this Report
Marapi Central Sumatra	VSI reported that the Marapi eruption at 0814 on 16 April produced a cauliflower-shaped black ash plume that rose 2 km above the summit. Ash, lapilli, and volcanic bombs were ejected during the eruption and fell within the crater. In addition, ash fell in many villages on the S and SW flanks of the volcano. Within 1-4 km from the summit the thickness of the ash deposits was between 2 and 3 cm. Until 18 April approximately 150 smaller explosions continuously occurred. The 16 April eruption was preceded by shallow volcanic earthquakes that began on 7 April and by continuous volcanic tremor recorded on 9 April. Small eruptions occurred at 1283 and 1600 on 13 April. VSI had increased the Alert Level at Marapi from 1 to 2 following the minor activity that began on 13 April. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Masaya | 25 April-1 May 2001 | New Activity / UnrestCite this Report
Masaya Nicaragua	INETER personnel reported that volcanic activity at Masaya decreased following the 23 April explosion. Small explosions were observed on 24 and 25 April, but by 27 April only the continuous emission of gas at normal levels was observed with few episodes of strong degassing. Likewise, after the 23 April explosion the level of SO2 emission decreased and normal levels of seismic activity were recorded. INETER warned that further explosions may occur that could affect areas near the crater (within ~500 m). A tourist at the scene during the 23 April explosion stated that injuries were more serious than was reported either here or in news accounts. Over 100 tourists were near the crater when the explosion occurred, including infants and elderly persons. At least 15 people sustained injuries (bruises and cuts) and one person suffered a broken arm. Source: Instituto Nicaragüense de Estudios Territoriales (INETER)
Sheveluch | 25 April-1 May 2001 | New Activity / UnrestCite this Report
Sheveluch Central Kamchatka (Russia)	Following the sharp increase in seismic activity on 22 April the number and magnitude of seismic events continued to increase at Shiveluch until 27 April. The largest earthquake occurred on 27 April (M 4) and the number and magnitude of earthquakes began to slightly decrease on 28 April. Several gas-and-steam plumes that reached a maximum height of 700 m above the volcano were observed starting on 28 April. As of 1 May seismic activity was still significantly above background levels. KVERT stated that the trend of the seismic activity is similar to the increase that preceded the violent 1993 eruption. The Concern Color Code at Shiveluch remained at Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Ulawun | 25 April-1 May 2001 | New Activity / UnrestCite this Report
Ulawun New Britain (Papua New Guinea)	According to the Darwin VAAC, a pilot reported observing a "smoke" cloud produced from Ulawun at 0730 on 30 April. The cloud was at an altitude of ~9 km a.s.l. and drifting to the NW and SW. Satellite imagery indicated that the cloud may have reached ~13.7 km a.s.l. and that the eruption ceased by ~1530 on 30 April. The Rabaul Volcanological Observatory stated that Ulawun is at a high alert level and further eruptions are possible. Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Cleveland | 25 April-1 May 2001 | Continuing ActivityCite this Report
Cleveland Chuginadak Island (USA)	Volcanic unrest continued at Cleveland through 27 April. During this time a thermal anomaly was observed on satellite imagery when weather permitted. Low pulses of volcanic tremor continued to be detected by an AVO seismic network 230 km to the E of the volcano. AVO had received no reports of significant volcanic activity from either pilots, residents, or satellite remote-sensors since the last eruption on 19 March. Source: US Geological Survey Alaska Volcano Observatory (AVO)
Etna | 25 April-1 May 2001 | Continuing ActivityCite this Report
Etna Sicily (Italy)	According to the Italy's Volcanoes website, activity at Etna's summit craters progressively increased beginning on about 20 April. Lava effusion from a vent on the lower NNE flank of Southeast Crater cone continued, with an increase in the effusion rate on 26 April. Ash vented from Bocca Nuova and light gas was emitted from a vent on the NNE flank of Southeast Crater. Source: Italy's Volcanoes
Ijen | 25 April-1 May 2001 | Continuing ActivityCite this Report
Ijen Eastern Java	During 16-23 April there was an increase in the number of shallow volcanic earthquakes (ten) in comparison to the previous week. Seismographs also recorded one deep volcanic, and two tectonic earthquakes. The volcano remained at Alert Level 2 (on a scale of 1-4). Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Inielika | 25 April-1 May 2001 | Continuing ActivityCite this Report
Inielika Flores Island	VSI reported that during 16-23 April seismic activity increased at Inielika in comparison to the previous week. Seismographs recorded five deep volcanic, ten shallow volcanic, and eleven tectonic earthquakes. Inielika is at Alert Level 2 (on a scale of 1-4). The previous report of significant volcanic activity occurred on 11 January 2001 when minor explosions began. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Karangetang | 25 April-1 May 2001 | Continuing ActivityCite this Report
Karangetang Sangihe Islands	During 16-23 April lava flowed from crater I to a maximum distance of 50 m, and lava avalanches often originated from the end of the lava flow and traveled about 750 m to the Nanitu River. In addition, a medium-gray plume that likely contained ash rose 50-300 m above the main crater, and a possible steam cloud from crater II rose 200 m above the summit. A red-colored reflection was visible rising 25 m above the volcano. Karangetang remained at Alert Level 2 (on a scale of 1-4). Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Kilauea | 25 April-1 May 2001 | Continuing ActivityCite this Report
Kilauea Hawaiian Islands (USA)	Lava continued to flow down the Pulama pali and across the coastal flat. On 25 April a small stream of lava reached the sea for the first time since late January. The lava stopped trickling into the sea on 29 April. On that day an unstable block of the lava bench fell into the sea, producing a loud noise and generating an explosion that tossed rocks onto dry land. A M 4.4 earthquake on the afternoon of 25 April was followed by a few small aftershocks during the rest of the week. A swarm of long-period earthquakes that began on 18 April continued through at least 27 April. The tilt at the summit was neither flat nor consistently in one direction or the other. Tiltmeters along the east rift zone indicated that there was no significant deformation. Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Mayon | 25 April-1 May 2001 | Continuing ActivityCite this Report
Mayon Luzon (Philippines)	PHIVOLCS reported that during the week ending on 22 April there had been a total of 42 low-frequency earthquakes and 11 high-frequency short-duration harmonic tremors. The SO2 flux during the same period averaged 3,400 metric tons/day, which is still significantly above the baseline value of 500 tons/day. Deformation monitoring showed that the volcano was inflated, but the present trend revealed insignificant change. Moderate steaming was typical. The crater was visible, but no glow was observed. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Merapi | 25 April-1 May 2001 | Continuing ActivityCite this Report
Merapi Central Java	During 16-23 April lava avalanches continued to flow down the Sat, Senowo, Lamat, and Bebeng rivers, with a maximum runout distance of 2 km. Fumaroles emitted gas that rose up to 500 m above the summit. Seismic activity continued to be dominated by avalanche earthquakes. Merapi remained at Alert Level 2 (on a scale of 1-4). Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Popocatepetl | 25 April-1 May 2001 | Continuing ActivityCite this Report
Popocatepetl Mexico	CENAPRED reported that at 0819 on 29 April a moderate explosion occurred at Popocatépetl that lasted for 1 minute and produced an ash cloud that rose 2 km above the volcano's summit and drifted to the ENE. A pilot reported that the ash cloud reached an altitude of 9 km a.s.l. Light ash fall was reported in San Pedro Benito Juárez ~10 km SE of the volcano's summit. Throughout the day several episodes of harmonic tremor occurred. Based on information from the Mexico City MWO, the Washington VAAC reported that another eruption occurred later the same day at 1310. It produced an ash cloud that rose 6.7-7.6 km a.s.l. The volcano remained at Alert Level Yellow Phase III, with a restricted 12-km-radius area. Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC), Associated Press
Semeru | 25 April-1 May 2001 | Continuing ActivityCite this Report
Semeru Eastern Java	Volcanic activity increased at Semeru in comparison to the previous week, with an increase in explosion and deep volcanic earthquakes. Seismographs recorded 550 explosion events, 149 avalanche events, and ten tectonic earthquakes. Gas explosions rose up to 300 m above the volcano. Semeru remained at Alert Level 2 (on a scale of 1-4). Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Soufriere Hills | 25 April-1 May 2001 | Continuing ActivityCite this Report
Soufriere Hills Montserrat	MVO reported that during 20-27 April volcanic activity at Soufrière Hills remained low, with few rockfalls and little seismicity. A very small amount of growth occurred on the S side of the lava dome, which was accompanied by occasional ash venting. Sulfur dioxide flux also remained low. Source: Montserrat Volcano Observatory (MVO)
Tungurahua | 25 April-1 May 2001 | Continuing ActivityCite this Report
Tungurahua Ecuador	Based on information from the IG, the Washington VAAC reported that several small eruptions occurred at Tungurahua and that lahars were active in several sectors of the volcano. At 1600 on 25 April a pilot reported that ash was visible over the volcano at an altitude of ~7 km. Seismic activity indicated that brief eruptions occurred at 1230 on 28 April and at 1130 on 29 April, but extensive cloudiness prevented observations of the ash clouds. On 29 and 30 April lahars traveled to the Pampas, Cusuá, Hacienda, and Achupashal sectors and the river levels rose in the Ulba and Mandur sectors. The lahars in the Pampas sector blocked the Pelileo-Baños channel during 0710 to 1100 on 29 April and destroyed the highway. The IG warned that rainy conditions may cause more lahars and rising river levels near the volcano. Sources: Washington Volcanic Ash Advisory Center (VAAC), Instituto Geofísico-Escuela Politécnica Nacional (IG)

Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 18,995 individual reports over 1,169 weeks (average of 16 per week) on 329 different volcanoes.

Use the dropdowns to choose the year and week for archived Weekly Reports.

 News Feeds and Google Placemarks

 Criteria & Disclaimers

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.

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.

5. USGS Disclaimer Statement for this Website:

Information presented on this website is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. We strongly recommend that USGS data be acquired directly from a USGS server and not through other sources that may change the data in some way. While USGS makes every effort to provide accurate and complete information, various data such as names, telephone numbers, etc. may change prior to updating. USGS welcomes suggestions on how to improve our home page and correct errors. USGS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of furnished data.

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For site security purposes and to ensure that this service remains available to all users, this government computer system employs software programs to monitor network traffic to identify unauthorized attempts to upload or change information, or otherwise cause damage. Unauthorized attempts to upload information or change information on this website are strictly prohibited and may be punishable under the Computer Fraud and Abuse Act of 1986 and the National Information Infrastructure Protection Act. Information may also be used for authorized law enforcement investigations. (Last modified September 21, 1999.)

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
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)