4-4-4-4-4-4-4-4-4-4-4-4-4 From: "Kuhn, Sally" <KUHNS@xxxxxx> Smithsonian / USGS Weekly Volcanic Activity Report 8-14 May 2024 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdivuqJQlDQ$> New Activity/Unrest: Ibu, Halmahera | Marapi, Central Sumatra | Purace, Colombia | Ruang, Sangihe Islands | Sheveluch, Central Kamchatka (Russia) | Taal, Luzon (Philippines) | Tofua, Tonga Ridge | Ubinas, Peru Ongoing Activity: Aira, Kyushu (Japan) | Dukono, Halmahera | Ebeko, Paramushir Island (Russia) | Fernandina, Isla Fernandina (Galapagos) | Great Sitkin, Andreanof Islands (USA) | Lewotobi, Flores Island | Manam, Northeast of New Guinea | Merapi, Central Java | Reykjanes, Reykjanes Peninsula | Semeru, Eastern Java | Suwanosejima, Ryukyu Islands (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 Ibu | Halmahera | 1.488°N, 127.63°E | Summit elev. 1325 m PVMBG reported that the eruption at Ibu was intensifying. At 0158 on 8 May a dense gray ash plume rose 2 km above the summit, produced lightning in the plume, and drifted E and SE. Incandescence from the crater was visible and roaring could be heard in areas as far away as the Ibu observation post (9 km W). Seismicity was at high levels. The Alert Level was raised to 3 (the second highest level on a four-level scale) and the public was advised to stay 3 km away from the active crater and 5 km away from the N crater wall opening. Additional ash plumes that same day were gray-to-white or gray-to-black, rose 1.5-2 km, and drifted NE, E, and SE. Dense gray ash plumes rose 1.2-1.5 km and drifted E on 9 May. At 0024 on 11 May a dense gray ash plume rose 4 km and drifted N and NW and at 0912 a dense gray-to-black ash plume rose 5 km and drifted W. 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> Marapi | Central Sumatra | 0.38°S, 100.474°E | Summit elev. 2885 m PVMBG reported that unrest at Marapi (on Sumatra) was ongoing during 8-14 May. White gas-and-steam plumes rose 200-300 m above the summit and drifted in multiple directions on most days; no emissions were visible on 10 May. An eruptive event was recorded on 10 May, though plumes were not visible. Lahars generated by intense rainfall occurred around 2100 on 11 May and caused several fatalities, evacuations, and widespread damage in the Agam Regency. The lahars originated in the Malana or Lona drainage on Marapiâ??s flank and significantly impacted several areas including in the Agam, Tanah Datar, Padang Panjang, and Padang Pariaman districts. Aid efforts were delayed by damage to bridges and several sections of roads between villages. Close to 200 homes were damaged or missing, around 72 hectares of fields were affected, and mosques were damaged. Search-and-rescue efforts were suspended overnight during 11-12 May due to lack of light and continuing flooding in upstream areas. As of 1300 on 13 May there were 15 people that remained missing. The number of evacuees totaled 1,159 in the Agam Regency and 2,039 in the Tanah Datar Regency. Accordion to a news report the death toll reached 43 people on 15 May. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 4.5 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. Sources: 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> ; Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/ <https://urldefense.com/v3/__http://www.bnpb.go.id/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcditSd8E5aw$> ; Antara News https://www.antaranews.com/berita/4104192/jumlah-korban-banjir-lahar-di-sumbar-bertambah-jadi-58-orang-pada-rabu <https://urldefense.com/v3/__https://www.antaranews.com/berita/4104192/jumlah-korban-banjir-lahar-di-sumbar-bertambah-jadi-58-orang-pada-rabu__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiufxJONLg$> ; Antara News https://www.antaranews.com/berita/4104786/korban-banjir-bandang-di-agam-ditemukan-5-km-dari-lokasi-bencana <https://urldefense.com/v3/__https://www.antaranews.com/berita/4104786/korban-banjir-bandang-di-agam-ditemukan-5-km-dari-lokasi-bencana__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiulEba4mw$> Purace | Colombia | 2.32°N, 76.4°W | Summit elev. 4650 m Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico Colombiano (SGC) reported that the number of both volcanic tremor (VT) and long-period (LP) seismic events at Puracé were stable during 7-13 May with only a slight increase in both the number and intensity of LP events on 9 May. The VT events had low magnitudes and were located at depths up to 4 km beneath the volcano and its E flank. The largest VT events were a M 1.8 recorded at 2351 on 7 May and at 2202 on 10 May. LP earthquakes were located in similar areas as the VT events, at depths less than 2 km. Earthquakes indicating magma movement were recorded during 7-9 May. Inclement weather sometimes prevented visual observations of emissions, though during the second part of the week diffuse fumarolic emissions from the crater and the crater rim were visible. Both carbon dioxide and sulfur dioxide emissions remained above baseline levels. The Alert Level remained at Orange (the second highest level on a four-color scale). Geologic Summary. Puracé in Colombia consists of an andesitic stratovolcano with a 500-m-wide summit crater constructed over a dacitic shield volcano. It lies at the NW end of a volcanic massif opposite Pan de Azúcar stratovolcano, 6 km SE. A NW-SE-trending group of seven cones and craters, Los Coconucos, lies between the two larger edifices. Frequent explosive eruptions in the 19th and 20th centuries have modified the morphology of the summit crater. The largest eruptions occurred in 1849, 1869, and 1885. Source: Servicio Geológico Colombiano (SGC) https://www2.sgc.gov.co/volcanes/index.html <https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdit6EzRB8Q$> Ruang | Sangihe Islands | 2.3°N, 125.37°E | Summit elev. 725 m PVMBG reported that during 1-12 May seismicity at Ruang was characterized by decreasing numbers of volcanic earthquakes and continuous tremor with decreasing amplitudes. During 8-13 May white plumes rose 200-400 m above the summit and drifted in multiple directions. The Alert Level was lowered to 3 (the second highest level on a scale of 1-4) and the public was warned to stay 4 km away from the active crater. Geologic Summary. Ruang volcano is the southernmost volcano in the Sangihe Island arc, north of Sulawesi Island; it is not the better known Raung volcano on Java. The 4 x 5 km island volcano is across a narrow strait SW of the larger Tagulandang Island. The summit contains a crater partially filled by a lava dome initially emplaced in 1904. Explosive eruptions recorded since 1808 have often been accompanied by lava dome formation and pyroclastic flows that have damaged inhabited areas. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m KVERT reported that the new lava dome at Sheveluch, named Karan-1, continued to grow during 3-9 May. Strong steam-and-gas emissions rose from the active area and incandescence at the dome was visible at night. A daily intense and large thermal anomaly over the dome was identified in satellite images. Kamchatka Volcanological Station volcanologists conducted field work on 8 May, including photos and drone observations of the new dome. At that time the dome was at least 70 m high, actively growing and, spalling rock avalanches down the flanks. The Aviation Color Code remained at Orange (the third 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. Sources: 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiubTTntyw$> ; Kamchatka Volcanological Station http://volkstat.ru/ <https://urldefense.com/v3/__http://volkstat.ru/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiuf2HHScg$> Taal | Luzon (Philippines) | 14.0106°N, 120.9975°E | Summit elev. 311 m PHIVOLCS reported ongoing unrest at Taal during 8-14 May. Sulfur dioxide emissions decreased during the previous week, with emissions averaged 2,191 tonnes per day (t/d) on 6 May. Minor phreatic events were recorded during 0827-0831 on 8 May in seismic and infrasound data. The events produced white steam plumes that rose 2 km above Main Crater and drifted SW based on webcam images. Sulfur dioxide emissions increased slightly on 9 May to 2,346 (t/d). A series of phreatic events were visible in webcam images during 0703-0709, 0717-0718, 0752-0754, 0757-0800, and a fifth that ended at 1029 on 10 May. Steam plumes rose 100-300 m and drifted SW. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ) and to take extra precautions around Main Crater, when boating on Taal Lake, and along the Daang Kastila fissure. Geologic Summary. Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities. 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdisIPM2buA$> Tofua | Tonga Ridge | 19.75°S, 175.07°W | Summit elev. 515 m Tonga Geological Services reported that unrest at Tofua continued during 8-14 May. Thermal anomalies were detected daily and had intensities that fluctuated at low levels. The Aviation Color Code remained at Yellow (the second lowest color on a four-color scale); the Maritime Alert Level remained at Orange (the second highest level on a four-color scale) and mariners were advised to stay 2 km away from the island; the Alert level for residents of Vavaâ??u and Haâ??apai remained at Green (the lowest color on a four-color scale). Geologic Summary. The low, forested Tofua Island in the central part of the Tonga Islands group is the emergent summit of a large stratovolcano that was seen in eruption by Captain Cook in 1774. The summit contains a 5-km-wide caldera whose walls drop steeply about 500 m. Three post-caldera cones were constructed at the northern end of a cold fresh-water caldera lake, whose surface lies only 30 m above sea level. The easternmost cone has three craters and produced young basaltic-andesite lava flows, some of which traveled into the caldera lake. The largest and northernmost of the cones, Lofia, has a steep-sided crater that is 70 m wide and 120 m deep and has been the source of historical eruptions, first reported in the 18th century. The fumarolically active crater of Lofia has a flat floor formed by a ponded lava flow. Source: Tonga Geological Services, Government of Tonga https://www.facebook.com/tongageologicalservice <https://urldefense.com/v3/__https://www.facebook.com/tongageologicalservice__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcditN0509Pg$> Ubinas | Peru | 16.345°S, 70.8972°W | Summit elev. 5608 m Instituto GeofÃsico del Perú (IGP) reported that thermal anomalies from the main crater floor at Ubinas were identified almost daily during 7-14 May. Ash, gas, and steam plumes rose to 1.1 km above the crater rim during 7-8 May. Similar plumes emitted continuously for a period of time on 12 May rose to 1.1 km above the crater rim and drifted S and SE. The Alert Level remained at Yellow (the second level on a four-color scale) and the public was warned to stay 2 km away from the crater. Geologic Summary. The truncated appearance of Ubinas, Perú's most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions. Source: Instituto GeofÃsico del Perú (IGP) http://www.igp.gob.pe/ <https://urldefense.com/v3/__http://www.igp.gob.pe/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcditLP25f3w$> Ongoing Activity Aira | Kyushu (Japan) | 31.5772°N, 130.6589°E | Summit elev. 1117 m JMA reported ongoing eruptive activity at Minamidake Crater (Aira Calderaâ??s Sakurajima volcano) during 6-13 May with nighttime crater incandescence. Very small eruptive events were recorded. Sulfur dioxide emissions were high, averaging 2,000 tons per day on 7 May. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 1 km away from both craters. Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdisLzYOxRA$> Dukono | Halmahera | 1.6992°N, 127.8783°E | Summit elev. 1273 m PVMBG reported that the eruption at Dukono was ongoing during 8-14 May. Gray-and-white ash plumes rose 450-1,200 m above the summit and drifted E and SE almost daily; emissions were not observed on 14 May. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone. Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the N-flank Gunung Mamuya cone. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> Ebeko | Paramushir Island (Russia) | 50.686°N, 156.014°E | Summit elev. 1103 m KVERT reported that moderate explosive activity was ongoing at Ebeko during 3-10 May According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions on 2 and 6 May generated ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. and drifted SE and S. A thermal anomaly was identified in satellite images on 3 and 6 May; on other days either no activity was observed or weather conditions prevented views. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted. Geologic Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php <https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiubTTntyw$> Fernandina | Isla Fernandina (Galapagos) | 0.37°S, 91.55°W | Summit elev. 1476 m Instituto GeofÃsico-Escuela Politécnica Nacional (IG-EPN) reported that the eruption at Fernandina decreased during 8-14 May. Sulfur dioxide emissions, measured using satellite data, ceased to be detected on 8 May, possibly indicating a decline in activity. Daily thermal anomalies from the lava flow were identified in satellite images. Geologic Summary. Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic "overturned soup bowl" profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 km3 section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake. Source: Instituto GeofÃsico-Escuela Politécnica Nacional (IG-EPN) http://www.igepn.edu.ec/ <https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiujOhsN7Q$> Great Sitkin | Andreanof Islands (USA) | 52.076°N, 176.13°W | Summit elev. 1740 m AVO reported that slow lava effusion in Great Sitkinâ??s summit crater likely continued during 8-14 May. Seismicity was low. Weather clouds fully or partly obscured satellite and webcam views. The active portion of the lava flow was warm and snow-free in partly-cloudy webcam views during 13-14 May.The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale). Geologic Summary. The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger volcano capped by a small, 0.8 x 1.2 km ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an older edifice and produced a submarine debris avalanche. Deposits from this and an even older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano. The summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 m. The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Eruptions have been recorded since the late-19th century. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ <https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdisGsyIkxQ$> Lewotobi | Flores Island | 8.542°S, 122.775°E | Summit elev. 1703 m PVMBG reported that an eruption at Lewotobiâ??s Laki-laki volcano continued during 8-14 May. White steam-and-gas plumes rose 50-150 m above the summit and drifted in multiple directions during 8-9 and 12 May; eruptive events were occasionally recorded during those days though emission details were unknown. Gray-to-white ash plumes rose 50-200 m above the summit and drifted SW and W during 10-11 and 13-14 May. The Alert Level remained at 2 (the second lowest level on a scale of 1-4) and the public was warned to stay outside of the exclusion zone, defined as a 2-km radius around Laki-laki crater, 3 km to the NNE, and 5 km on the NE flanks. 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> Manam | Northeast of New Guinea | 4.08°S, 145.037°E | Summit elev. 1807 m The Darwin VAAC reported that on 12 May an ash plume from Manam rose to 4.6 km (15,000 ft) a.s.l. and drifted E based on satellite images and weather models. The plume had dissipated by 0030 on 13 May. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml <https://urldefense.com/v3/__http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdivUACsyWA$> Merapi | Central Java | 7.54°S, 110.446°E | Summit elev. 2910 m BPPTKG reported that the eruption at Merapi (on Java) continued during 3-9 May. Seismicity had intensified compared to the previous week. The SW lava dome produced 176 lava avalanches that traveled as far as 2 km down the Bebeng drainage on the SW flank. Morphological changes to the SW lava dome were due to continuing effusion and collapses of material. The volume of the SW dome was an estimated 2,299,600 cubic meters and the dome in the main crater was stable at an estimated 2,360,000 cubic meters based on a 9 May drone survey and webcam images. 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiuAGS48Zg$> Reykjanes | Reykjanes Peninsula | 63.817°N, 22.717°W | Summit elev. 140 m IMO reported that no active lava in the cone just E of Sundhnúk and along the fissure within the Reykanes volcanic system was visible in aerial photos taken during the evening of 8 May, indicating that the eruption was over. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) because magma continued to accumulate at depth at a consistent rate, increasing the likelihood of a new eruption. Seismicity was relatively stable with 50-80 earthquakes recorded each day during the previous week. Most of the earthquakes were below M 1, though a few earthquakes had magnitudes close to 2. Geologic Summary. The Reykjanes volcanic system at the SW tip of the Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level, comprises a broad area of postglacial basaltic crater rows and small shield volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous with and is considered part of the Reykjanes volcanic system, which is the westernmost of a series of four closely-spaced en-echelon fissure systems that extend diagonally across the Reykjanes Peninsula. Most of the subaerial part of the system (also known as the Reykjanes/Svartsengi volcanic system) is covered by Holocene lavas. Subaerial eruptions have occurred in historical time during the 13th century at several locations on the NE-SW-trending fissure system, and numerous submarine eruptions dating back to the 12th century have been observed during historical time, some of which have formed ephemeral islands. Basaltic rocks of probable Holocene age have been recovered during dredging operations, and tephra deposits from earlier Holocene eruptions are preserved on the nearby Reykjanes Peninsula. Source: Icelandic Meteorological Office (IMO) http://en.vedur.is/ <https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiuLn5Ae7Q$> Semeru | Eastern Java | 8.108°S, 112.922°E | Summit elev. 3657 m PVMBG reported that eruptive activity continued at Semeru during 8-14 May. White-and-gray ash plumes rose 300-800 m above the summit and drifted in multiple directions during 8-9 and 12-14 May. Several additional eruptive events were recorded during the week by the seismic network, though plumes were not visually confirmed. The Alert Level remained at 3 (the third highest 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!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdiviDNPWIQ$> Suwanosejima | Ryukyu Islands (Japan) | 29.638°N, 129.714°E | Summit elev. 796 m JMA reported that eruptive activity at Suwanosejima's Ontake Crater continued during 6-13 May. Crater incandescence was observed nightly in webcam images. An explosion was recorded at 2145 on 8 May though details of plumes were unknown. An explosion at 0831 on 9 May produced an ash plume that rose 400 m above the crater rim and drifted S. Eruptive events at 2339 on 9 May and at 0213 on 10 May generated ash plumes that rose 1.1-1.3 km above the crater rim and drifted SW. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1.5 km away from the crater. Geologic Summary. The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan's most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!bEiK24SYq2Fgo7mS5V1zE-BRcnivnMf3SgBheUaE4Yec9mpB-wibhFQ6l-reGBcnDPU_HgQncM5qegOcdisLzYOxRA$> 4-4-4-4-4-4-4-4-4-4-4-4-4 ============================================================== 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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