1-1-1-1-1-1-1-1-1-1-1-1-1-1 From: "Kuhn, Sally" <KUHNS@xxxxxx> Smithsonian / USGS Weekly Volcanic Activity Report 30 April-6 May 2025 Sally Sennert - Weekly Report Editor (kuhns@xxxxxx) URL: https://volcano.si.edu/reports_weekly.cfm <https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBWHgBUTuQ$> New Activity/Unrest: Bezymianny, Russia | Bulusan, Philippines | Home Reef, Tonga | Klyuchevskoy, Russia | Northern EPR at 9.8°N, Undersea Features | Poas, Costa Rica Ongoing Activity: Ahyi, United States | Aira, Japan | Atka Volcanic Complex, United States | Dukono, Indonesia | Etna, Italy | Great Sitkin, United States | Ibu, Indonesia | Kanlaon, Philippines | Karymsky, Russia | Kilauea, United States | Lewotobi, Indonesia | Lewotolok, Indonesia | Marapi, Indonesia | Merapi, Indonesia | Nyamulagira, DR Congo | Popocatepetl, Mexico | Reventador, Ecuador | Semeru, Indonesia | Sheveluch, Russia | Suwanosejima, Japan 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, these reports are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports about recent activity are published in issues of the Bulletin of the Global Volcanism Network. Note that 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. New Activity/Unrest Bezymianny | Russia | 55.972°N, 160.595°E | Summit elev. 2882 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that an explosive eruption at Bezymianny on 23 April produced ash plumes that rose 11 km (36,100 ft) a.s.l. and pyroclastic flows that descended the Vostochnaya (E) and Yuzhnaya (S) drainages. The ash cloud drifted SW and then SE as far as 900 km during 23-25 April. Following the explosions the dome continued to erupt viscous lava and small, hot avalanches of material descended the flanks. A bright thermal anomaly was visible in satellite images through 1 May. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) on 29 April. Geologic Summary. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php <https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVGEJ6hlA$> Bulusan | Philippines | 12.769°N, 124.056°E | Summit elev. 1535 m The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing unrest at Bulusan during 30 April-5 May. The seismic network recorded 50-127 daily volcanic earthquakes, including 2-52 periods of volcanic tremor during 30 April-3 May that each lasted 1-58 minutes. Gas-and-steam emissions of variable densities rose as high has 500 m above the summit and drifted E, WNW, W, and WSW; views were obscured on 2 May. Daily averages of sulfur dioxide emissions ranged from 809 to 2,131 tonnes per day. The Alert Level remained at 1 (the second lowest level on a scale of 0-5). The public was reminded not to enter the 4-km-radius Permanent Danger Zone (PDZ) and to be vigilant within the 2-km Extended Danger Zone (EDZ) on the SE flank. Geologic Summary. 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. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ <https://urldefense.com/v3/__http://www.phivolcs.dost.gov.ph/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUtfzOXFQ$> Home Reef | Tonga | 18.992°S, 174.775°W | Summit elev. -10 m The Tonga Geological Services reported continuing activity at Home Reef with lava effusion and explosive activity at the main vent. A cone had grown around the vent and was 50-100 m high, based on a 26 April satellite image, and the vent had enlarged to about 175 m by 135 m in dimension. New deposits of material were visible on the W and SW flanks, nearly covering the lava lobes emplaced in November and December 2024. A volcanic ash plume was identified in a satellite image at 1354 on 29 April. In a 1 May image steam plumes rose from the vent and water around the island was discolored. Moderate thermal anomalies continued to be detected by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system at least through 3 May. The island was about 540 m N-S and 440 m W-E. According to the Wellington VAAC intermittent, low-level ash plumes were visible in satellite images and sometimes observed by pilots during 29-30 April and on 3 May rising 0.9-1.2 km (3,000-4,000 ft) a.s.l. and drifting N, NW, W, and SW. The Aviation Color Code remained at Orange (the second highest level on a four-level scale), the Maritime Alert Level remained at Orange (the third level on a four-level scale), and mariners were advised to stay at least 2 nautical miles (3.7 km) away from the island. The Alert Level for residents of Vavaâ??u and Haâ??apai remained at Green (the first level on a four-level scale). Geologic Summary. Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, large amounts of floating pumice, and an ephemeral 500 x 1,500 m island, with cliffs 30-50 m high that enclosed a water-filled crater. In 2006 an island-forming eruption produced widespread dacitic pumice rafts that drifted as far as Australia. Another island was built during a September-October 2022 eruption. Sources: Tonga Geological Services, Government of Tonga https://www.facebook.com/tongageologicalservice <https://urldefense.com/v3/__https://www.facebook.com/tongageologicalservice__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUE_0gU-Q$> ; Wellington Volcanic Ash Advisory Center (VAAC) http://vaac.metservice.com/ <https://urldefense.com/v3/__http://vaac.metservice.com/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU3_S2_Pg$> Klyuchevskoy | Russia | 56.056°N, 160.642°E | Summit elev. 4754 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a thermal anomaly at Klyuchevskoy was identified in satellite images during 24 April-1 May. Lava fountaining occurred deep within the summit crater and incandescence was occasionally visible above the crater rim. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted. Geologic Summary. Klyuchevskoy is the highest and most active volcano on the Kamchatka Peninsula. Since its origin about 6,000 years ago, this symmetrical, basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during approximately the past 3,000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 and 3,600 m elevation. Eruptions recorded since the late 17th century have resulted in frequent changes to the morphology of the 700-m-wide summit crater. These eruptions over the past 400 years have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php <https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVGEJ6hlA$> Northern EPR at 9.8°N | Undersea Features | 9.83°N, 104.3°W | Summit elev. -2500 m In a 2 May press release the Woods Hole Oceanographic Institution reported that scientists from multiple institutions and universities took part in an expedition to the Northern East Pacific Rise (EPR) at 9.8°N, an area about 1,300 miles west of Costa Rica, and observed a seafloor eruption. On 28 April a team of scientists aboard the Alvin submersible observed a vibrant ecosystem at the Tica hydrothermal vents, ~2,500 m below the surface, including tubeworms, mussels, crabs, fish, and many other animals. During another dive the next day they noted particulate matter in the water column and slightly elevated temperatures. They turned on the lights and saw that Tica was barren, with dead stands of tubeworms covered in fresh basalt and flashes of incandescence indicating ongoing eruptive activity. The dive was aborted, and planned future dives during the length of the expedition were cancelled due to the safety concerns surrounding the eruption. Scientists continued to gather data at Tica by lowering instrumentation into the water until the end of the expedition on 3 May. Precursory activity including rising temperatures and changes in water chemistry at the vents recorded by previously installed instrumentation. Geologic Summary. A series of dives with the submersible Alvin in 1991 on the East Pacific Rise at about 9°50'N detected evidence for a very recent, possibly ongoing, eruption. Hot-vent animal communities documented during November-December 1989 had been buried by fresh basaltic lava flows, and the scorched soft tissues of partially buried biota had not yet attracted bottom scavengers. Fresh black smoker chimneys and new lava flows were present. This site is south of the Clipperton Fracture Zone at a depth of about 2,500 m, and about 1,000 km SW of Acapulco, México; the south end of the Lamont Seamount chain is about 10 km NW. This is also the location where lava flows previously estimated as being less than roughly 50 years old had been found. Later dating using very short half-life radionuclides from dredged samples confirmed the young age of the eruption and indicated that another eruptive event had taken place in late 1991 and early 1992. An eruption in 2005-2006 produced lava flows that entrapped previously emplaced seismometers. Source: Woods Hole Oceanographic Institution https://www.whoi.edu/ <https://urldefense.com/v3/__https://www.whoi.edu/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBWc43EzCA$> Poas | Costa Rica | 10.2°N, 84.233°W | Summit elev. 2697 m The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported continuous gas-and-steam emissions, ash-and-gas emissions sometimes lasting hours, and explosions at Poás during 30 April-6 May. Inflation continued to be detected. Seismic and infrasound sensors recorded seismic-acoustic signals indicating fluctuating eruptive activity with frequent more intense eruptive pulses. The webcams recorded the emissions and incandescence at the vents. During 29-30 April ash-and-gas plumes rose a few hundred meters above the crater rim and drifted SW, causing significant ashfall in the Sarchi area (18 km SW). The density of the ash content was higher in the morning and early afternoon on 30 April. Around 0300 on 1 May a team conducted a drone overflight and measured a temperature of 180 degrees Celsius, indicating no lava near the surface. A more intense eruptive pulse at 0315 sent ash-and-gas 500 m above the crater rim. Burning molten sulfur at the vents was visible at night during 1-2 May and continued to be visible during dark hours the rest of the week. Beginning at 0500 on 2 May ash emissions were continuous for at least three hours, producing a black-and-white plume that rose less than 1 km above the crater rim and drifted W. Several eruptive pulses with white-and-gray plumes were recorded during the day, notably at 1520, and drifted W. Ashfall was reported in Grecia and Naranjo, and residents observed rising ash-laden water levels in the Desague (W) and Anonos (N) rivers. Incandescent material was ejected mainly to the W and deposited on the crater floor. Sulfur dioxide emissions averaged 612 tons per day (t/d). Ashfall was reported in San Juan de Grecia (17 km SW), Montes de Oca (37 km SE), and San José (34 km SE), and a sulfur odor was detected in Alajuela (San Ramón, 29 km WSW). Overnight during 2-3 May incandescence from sulfur combustion suggested temperatures around 160 degrees Celsius. Eruptive pulses at 0300 and 0812 on 3 May generated ash-and-gas plumes that rose 500 m above the crater rim and drifted W. Sulfur dioxide emissions detected in satellite data were 508 t/d. Eruptive activity decreased during 3-4 May, characterized by vigorous white gas-and-steam plumes with less ash content. Sulfur combustion produced intense incandescence overnight. The ash content in the emissions increased at around 1100 and caused a darker plume that drifted W. An ash-and-gas plume from an eruptive pulse at 2030 rose 600 m above the crater rim and drifted W. At 2059 incandescent ballistics were ejected from Boca A and deposited onto the crater floor. Sulfur dioxide emissions measured by a Differential Optical Absorption Spectroscopy (DOAS) station on 5 May averaged 3,190 t/d (+/- 560 t/d), slightly lower than the same measurement made in April but higher compared to historical data. Steam-and-gas emissions continued on 6 May, though they were semi-continuous, less robust, and contained low or no ash content; plumes drifted SW. The volcanoâ??s Alert Level remained at 3 (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest color on a four-color scale). Geologic Summary. The broad vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the complex stratovolcano extends to the lower N flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, last erupted about 7,500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since an eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water. Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/ <https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUgts-Btw$> Ongoing Activity Ahyi | United States | 20.42°N, 145.03°E | Summit elev. -75 m Unrest at Ahyi Seamount continued during 25 April-1 May. Discolored water in the vicinity of the seamount was last identified in a satellite image on 25 April, indicating possible submarine activity. Signals coming from the direction of Ahyi were identified in data from underwater pressure sensors near Wake Island (about 2,270 km E) during 28 April-1 May. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale). Geologic Summary. Ahyi seamount is a large conical submarine volcano that rises to within 75 m of the ocean surface ~18 km SE of the island of Farallon de Pajaros in the northern Marianas. Water discoloration has been observed there, and in 1979 the crew of a fishing boat felt shocks over the summit area, followed by upwelling of sulfur-bearing water. On 24-25 April 2001 an explosive eruption was detected seismically by a station on Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15 km) at a location near the southern base of Ahyi. An eruption in April-May 2014 was detected by NOAA divers, hydroacoustic sensors, and seismic stations. Source: US Geological Survey https://www.usgs.gov/ <https://urldefense.com/v3/__https://www.usgs.gov/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVm28Tu-A$> Aira | Japan | 31.5772°N, 130.6589°E | Summit elev. 1117 m The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Calderaâ??s Sakurajima volcano) during 28 April-5 May. Nightly crater incandescence was visible at Minamidake Crater in webcam images, and very small eruptive events were recorded during 2-5 May. An eruptive event at 2336 on 29 April generated an ash plume that rose 1.1 km above the crater rim and drifted S. On 2 May sulfur dioxide emissions averaged 900 tons per day, the same as the previous measurement on 17 April. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of both the Minimadake and Showa craters. Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBX3BumaVg$> Atka Volcanic Complex | United States | 52.331°N, 174.139°W | Summit elev. 1518 m At 1200 on 5 May the Alaska Volcano Observatory (AVO) lowered the Volcano Alert Level for the Atka volcanic complex to Normal (the lowest level on a four-level scale) and the Aviation Color Code to Green (the lowest color on a four-color scale). AVO noted that no additional explosive activity was recorded after the small explosive event at 1034 on 25 April. Geologic Summary. The Atka Volcanic Complex consists of a central shield and Pleistocene caldera and four notable volcanic cones. A major explosive dacitic eruption accompanied formation of the caldera about 500,000 to 300,000 years ago; approximately half of the caldera rime remains, open towards the NW. The Sarichef cone, ~5 km ESE of the caldera rim, retains a symmetrical profile, unlike most other heavily eroded features outside the caldera to the S and W. The Kliuchef stratovolcano grew within the caldera and exhibits five eruptive vents striking NE, including two at the summit, that have been active in the Holocene. A 700-m-diameter crater 1 km NE of the summit may have been the source vent for a large 1812 CE eruption. Hot springs and fumaroles are located on the flanks of Kliuchef and in a glacial valley to the SW. The most frequently active volcano of the complex is Korovin, at the NE tip of Atka Island about 5 km N of Kliuchef. An 800-m-diameter crater on the SE side of the summit contains a deep circular pit that sometimes contains a crater lake thought to be the source of phreatic ash explosions. The smaller Konia cone, slightly offset to the E, lies between Kliuchef and Korovin. Most of the lava flows in the complex are basaltic, though some dacitic flows are also present. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ <https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVa5zlt8A$> Dukono | Indonesia | 1.6992°N, 127.8783°E | Summit elev. 1273 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued at high levels through 6 May. Daily eruptive events in 2025 were in the 60-394 range, with an average of 227 per day. Gas-and-ash plumes generally rose 200-2,500 m above the summit, though during 27 March-30 April plumes rose as high as 1,400 m above the summit. The plumes drifted E, NW, and W towards populated areas. On 30 April occasional rumbling was followed by a strong boom felt by residents as far as 11 km away. During 1-6 May white-and-gray ash plumes rose 100-1,500 m above the crater rim and drifted in variable directions. Minor ashfall was reported in Mamuya, 11 km N, on 1 May and rumbling was heard during 1-2 May. The Alert Level remained at Level 2 (on a scale of 1-4) and the public was warned to stay 4 km away from the Malupang Warirang Crater. Geologic Summary. The Dukono complex in northern Halmahera is on an edifice with a broad, low profile containing multiple peaks and overlapping craters. Almost continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the Gunung Mamuya cone, 10 km NE. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also had reported eruptions. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Etna | Italy | 37.748°N, 14.999°E | Summit elev. 3357 m The Sezione di Catania - Osservatorio Etneo (INGV) reported continuing activity at Etna during 28 April-4 May, characterized by Strombolian activity, lava fountains, and lava overflows at SE Crater and gas emissions at Bocca Nuova Crater, NE Crater, and Voragine. Activity at SE Crater began at 2357 on 29 April based on webcam views, though the views were obscured by dense weather clouds during the first hour. Visibility significantly improved at about 0200 on 30 April and by then lava was flowing over the SE Crater rim, with several branches advancing to the SE and S. Multiple vents at the summit of SE Crater produced explosive activity at variable intensities, with jets of material rising 300-400 m high. Strombolian explosions at the main vent in the W part of the crater became sustained at around 0245 producing pulsating lava fountains. Lava flows reached the base of the cone and fanned out towards Monte Frumento Supino. The activity decreased at around 0330 with lava fountaining changing to Strombolian activity that lasted for about three hours. By 0615 Strombolian activity was no longer visible and ash emissions rose 1,5 km above the summit and drifted SW. The ash emissions became discontinuous and then ceased at 0910. Satellite data from 2 May was used to map the flows. Both the SE and S flows were about 1.6 km long. Geologic Summary. Mount Etna, towering above Catania on the island of Sicily, has one of the world's longest documented records of 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 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. Source: Sezione di Catania - Osservatorio Etneo (INGV) http://www.ct.ingv.it/ <https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBW0815Y0A$> Great Sitkin | United States | 52.076°N, 176.13°W | Summit elev. 1740 m The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkinâ??s summit crater during 29 April-6 May. Small daily earthquakes were detected by the seismic network. Slightly elevated temperatures were identified in a few satellite images during 30 April-1 May. Weather clouds often obscured satellite and webcam views of the volcano. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale). Geologic Summary. The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger volcano capped by a small, 0.8 x 1.2 km ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an older edifice and produced a submarine debris avalanche. Deposits from this and an even older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano. The summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 m. The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Eruptions have been recorded since the late-19th century. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ <https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVa5zlt8A$> Ibu | Indonesia | 1.488°N, 127.63°E | Summit elev. 1325 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) lowered the Alert Level for Ibu to 2 (the second lowest level on a four-level scale) at 1700 on 1 May, based on visual observations and monitoring data that showed decreasing activity since February. Eruptive activity continued to be recorded, though plumes heights were lower and incandescent material was ejected only as far as 200 m from the crater rim. Seismic activity had decreased, and deformation data showed some signs of decreased pressure, or deflation. Daily gray, white-to-gray, or white-to-brown ash plumes rose 300-700 m above the crater rim and drifted in variable directions. Nighttime crater incandescence was visible in some webcam images. The public was advised to stay 2 km away from the active crater and 3.5 km away from the N crater wall opening. Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Kanlaon | Philippines | 10.4096°N, 123.13°E | Summit elev. 2422 m The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon during 29 April-5 May. The seismic network recorded 7-22 daily volcanic earthquakes. Daily sulfur dioxide emissions ranged from 457 to 2,794 tonnes per day; emissions were not reported on 3 May. Gas-and-steam plumes with moderate densities rose 150-600 m above the crater rim and drifted NW, W, and SW. The plumes occasionally contained ash on 29 April. The Alert Level remained at 3 (on a scale of 0-5); the public was warned to stay 6 km away from the summit and pilots were warned not to fly close to the volcano. Geologic Summary. Kanlaon volcano (also spelled Canlaon) forms the highest point on the Philippine island of Negros. The massive andesitic stratovolcano is covered with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller but higher active vent, Lugud crater, to the south. Eruptions recorded since 1866 have typically consisted of phreatic explosions of small-to-moderate size that produce minor local ashfall. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ <https://urldefense.com/v3/__http://www.phivolcs.dost.gov.ph/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUtfzOXFQ$> Karymsky | Russia | 54.049°N, 159.443°E | Summit elev. 1513 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that thermal anomalies over Karymsky were identified in satellite images during 24 and 28-30 April and on 1 May. Explosive activity began on 29 April and ash plumes generated during 29-30 April and on 1 May drifted 120 km SE, E, and NE. KVERT issued a Volcano Observatory Notice for Aviation (VONA) noting that explosions occurred at 1320 and 1830 on 30 April; the ash plume from the second explosion rose 3.5-4 km (11,500-13,100 ft) a.s.l. Dates are based on UTC times; specific events are in local time where noted. Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php <https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVGEJ6hlA$> Kilauea | United States | 19.421°N, 155.287°W | Summit elev. 1222 m The Hawaiian Volcano Observatory (HVO) reported that the eruption within Kilaueaâ??s Kaluapele summit caldera, from two vents along the SW margin of Halemaâ??umaâ??u Crater, continued at variable levels during 22 April-6 May. Incandescence at the S vent was visible during 22-25 April, then at both the N and S vents during 26 April-1 May. Weak spattering at the N vent was visible just before 1850 on 27 April. A tiny lava pool at the S vent was visible overnight during 29-30 April. Spattering at the N vent was visible along with flames from hydrogen gas burning in air during 29 April-1 May. Sulfur dioxide emissions averaged 1,350 tonnes per day (t/d) on 30 April, typical levels during periods with no lava fountains. At the N vent, cycles of dome fountaining, short lava overflows, and lava immediately draining back into the vent began at around 1149 on 1 May and lasted above nine hours. There were 26 cycles, with each lasting 10-15 minutes separated by about 10 minutes of repose. The activity intensified at around 1845. Lava fountains became sustained at 2128 and rose up to 100 m. Fountaining lasted for seven hours and 52 minutes, ceasing at 0520 on 2 May. Lava flows covered about half of the crater floor. Sulfur dioxide emissions averaged 1,750 t/d later that same day. Incandescence at both vents was visible overnight during 3-5 May. Occasional spattering at the N vent was visible during 4-5 May. Activity increased on 5 May. During 1049-1800 there were about 30 cycles of dome fountaining and lava draining back into the N vent. Lava overflowed the vent rim several times producing short lava flows. At 1123 a short lava flow from the S vent advanced onto the crater floor. Incandescence from both vents was visible overnight during 5-6 May. Lava fountaining at the N vent began at 1728 on 6 May and fountains quickly rose at least 150 m. Fast-moving lava flows traveled across the crater floor. Fountains also rose from the S vent as high as 20 m. Fast-moving lava flows from mainly the N vent and somewhat from the S vent traveled across the crater floor, covering less than half of it. Activity ceased at 2158. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale). Geologic Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) https://volcanoes.usgs.gov/observatories/hvo/ <https://urldefense.com/v3/__https://volcanoes.usgs.gov/observatories/hvo/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUBzyY4dA$> Lewotobi | Indonesia | 8.542°S, 122.775°E | Summit elev. 1703 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Lewotobi Laki-laki continued during 30 April-6 May. Daily white plumes rose as high as 700 m above the crater rim and drifted in various directions. At 0522 on 30 April a dense gray ash plume rose 4 km above the crater rim and drifted N and NE. Incandescent material on the flanks was possibly visible in a webcam image from 0535. At 1107 on 2 May a dense gray-to-brown ash plume rose 3.5 km above the crater rim and drifted N and NE. Ash plumes at 1200 on 2 May and at 2106 on 3 May rose 1 km and 800 m above the crater rim, respectively, and drifted SW and W. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 6 km away from the center of Laki-laki. Geologic Summary. The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the "husband and wife"). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Lewotolok | Indonesia | 8.274°S, 123.508°E | Summit elev. 1431 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruption at Lewotolok was ongoing during 30 April-5 May. Daily white steam-and-gas plumes rose as high as 100 m above the summit of the cone and drifted NW, W, and SW. Nighttime webcam images showed incandescent material being ejected above the summit. Ash plumes rose 400-600 m and drifted SE and W during 3-4 May. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the vent and 2.5 km away on the S, SE, and W flanks. Geologic Summary. The Lewotolok (or Lewotolo) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano's high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Marapi | Indonesia | 0.38°S, 100.474°E | Summit elev. 2885 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity from Verbeek Crater at Marapi (on Sumatra) continued during 30 April-6 May. Eruptive events were detected at 1816 on 30 April and at 1438 on 1 May, though the events were not visually observed. At 1812 on 3 May an ash plume rose 800 m above the summit and drifted NE. An eruptive event was detected at 1331 on 4 May, though not visually observed. At 2209 on 4 May a dense gray ash plume rose 1 km above the summit and drifted E. Incandescence at the summit was visible in an image from 2226 that same day. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the active crater. Geologic Summary. Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra's most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Merapi | Indonesia | 7.54°S, 110.446°E | Summit elev. 2910 m The Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG) reported that the eruption at Merapi (on Java) continued during 25 April-1 May. Seismicity remained at high levels. The SW lava dome produced 62 lava avalanches that traveled as far as 2 km SW down the Bebeng drainage, 47 that traveled as far as 2 km SW down the Krasak drainage, and 148 that traveled as far as 2 km W down the Sat/Putih drainage. Small morphological changes to the SW lava dome resulted from continuing effusion and minor collapses of material. The hottest temperature was 249.3 degrees Celsius, and the volume of the dome had grown to an estimated 3,925,200 cubic meters, based on webcam images and a 26 April drone survey. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit, based on location. Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities. Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG) http://www.merapi.bgl.esdm.go.id/ <https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVqdx62uw$> Nyamulagira | DR Congo | 1.408°S, 29.2°E | Summit elev. 3058 m Satellite images acquired on 21 and 26 April and on 1 May showed continuing activity at Nyamulagira. Though weather clouds particularly obscured the summit area in all three scenes, bright thermal anomalies indicated continuing activity at the summit crater and active lava flows on the W flank. Geologic Summary. Africa's most active volcano, Nyamulagira (also known as Nyamuragira), is a massive high-potassium basaltic shield about 25 km N of Lake Kivu and 13 km NNW of the steep-sided Nyiragongo volcano. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Documented eruptions have occurred within the summit caldera, as well as from the numerous flank fissures and cinder cones. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Recent lava flows extend down the flanks more than 30 km from the summit as far as Lake Kivu; extensive lava flows from this volcano have covered 1,500 km2 of the western branch of the East African Rift. Source: Copernicus https://www.copernicus.eu/en <https://urldefense.com/v3/__https://www.copernicus.eu/en__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUE3HCDdw$> Popocatepetl | Mexico | 19.023°N, 98.622°W | Summit elev. 5393 m The Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 29 April-4 May. The seismic network recorded 11-35 long-period events per day, accompanied by steam-and-gas emissions; ash was detected in the emissions during 29-30 April. In addition, the seismic network recorded daily periods of tremor, sometimes characterized by harmonic and high-frequency signals, lasting from 34 minutes to three hours and 52 minutes. According to the Washington VAAC an ash plume was visible in webcam and satellite images on 10 April rising 5.8 km (20,000 ft) a.s.l. (about 400 m above the crater rim) and drifting SW. An event at around 0100 on 5 May ejected material onto the upper flanks and produced an ash plume that rose 6.4 km (21,000 ft) a.s.l. (as high as 1 km above the crater rim) and drifted E and ESE. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater. Geologic Summary. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time. Sources: Centro Nacional de Prevencion de Desastres (CENAPRED) https://www.gob.mx/cenapred <https://urldefense.com/v3/__https://www.gob.mx/cenapred__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBX-VniHgA$> ; Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html <https://urldefense.com/v3/__http://www.ssd.noaa.gov/VAAC/messages.html__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBUob7DSGA$> Reventador | Ecuador | 0.077°S, 77.656°W | Summit elev. 3562 m The Instituto GeofÃsico-Escuela Politécnica Nacional (IG-EPN) reported that eruptive activity continued at Reventador during 9-15 April. Seismicity included 57-100 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Multiple daily ash-and-gas plumes rose 300-1,300 m above the crater rim and drifted mainly NW, W, and SW. Webcams recorded multiple nightly instances of incandescent material descending the flanks as far as 1.1 km below the crater rim, particularly down the S and SE flanks. Weather clouds occasionally obscured views. SecretarÃa de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale). Geologic Summary. Volcán El Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic stratovolcano has 4-km-wide avalanche scarp open to the E formed by edifice collapse. A young, unvegetated, cone rises from the amphitheater floor to a height comparable to the rim. It has been the source of numerous lava flows as well as explosive eruptions visible from Quito, about 90 km ESE. Frequent lahars in this region of heavy rainfall have left extensive deposits on the scarp slope. The largest recorded eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents. Sources: Instituto GeofÃsico-Escuela Politécnica Nacional (IG-EPN) http://www.igepn.edu.ec/ <https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBWnEKQ3lw$> ; SecretarÃa de Gestión de Riesgos (SGR) http://www.gestionderiesgos.gob.ec/ <https://urldefense.com/v3/__http://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBXdg6fNhA$> Semeru | Indonesia | 8.108°S, 112.922°E | Summit elev. 3657 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru during 30 April-6 May, with multiple daily eruptive events recorded by the seismic network. Daily white-and-gray ash plumes rose 400-1,000 m above the summit and drifted in multiple directions. The Alert Level remained at 2 (the second lowest level on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards. Geologic Summary. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBU2ELvk_Q$> Sheveluch | Russia | 56.653°N, 161.36°E | Summit elev. 3283 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that lava extrusion may have continued at Sheveluchâ??s â??300 years of RASâ?? dome on the SW flank of Old Sheveluch and at the Young Sheveluch dome during 24 April-1 May. Daily thermal anomalies over the domes were identified in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted. Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php <https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBVGEJ6hlA$> Suwanosejima | Japan | 29.638°N, 129.714°E | Summit elev. 796 m The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 28 April-5 May. Incandescence was observed nightly in webcam images. An explosion at 0901 on 5 May generated an ash plume that rose 700 m above the crater rim and drifted S. The Alert Level remained at 2 (the second level on a five-level scale) and the public was warned to be cautious within 1.5 km of the crater. Geologic Summary. The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan's most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!YZ4qjEP-y6pqYItuSloAVw79lyUPIr-SvJa-nFnevBclZiPWuTFaK0SKUreyOYj7ApnYNrglMEEwFfLaMBX3BumaVg$> 1-1-1-1-1-1-1-1-1-1-1-1-1-1 ============================================================== Volcano Listserv is a collaborative venture among Arizona State University (ASU), Portland State University (PSU), the Global Volcanism Program (GVP) of the Smithsonian Institution's National Museum of Natural History, and the International Association for Volcanology and Chemistry of the Earth's Interior (IAVCEI). 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