Smithsonian / USGS Weekly Volcanic Activity Report
Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)
URL: http://volcano.si.edu/
New Activity/Unrest: Kilauea, Hawaiian Islands (USA) | Langila, New Britain (Papua New Guinea) | Merapi, Central Java (Indonesia) | Piton de la Fournaise, Reunion Island (France)
Ongoing Activity: Agung, Bali (Indonesia) | Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kirishimayama, Kyushu (Japan) | Klyuchevskoy, Central Kamchatka (Russia) | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Turrialba, Costa Rica
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, notices of volcanic activity posted on these pages 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 on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: 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
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
On 16 May HVO reported ongoing deflation at Kilauea’s summit, where the lava lake continued to recede in the Overlook Crater; by the afternoon the caldera floor had dropped a total of almost 1 m since the onset of the lake drainage. The drop of the floor stressed faults around the caldera causing earthquakes as strong at M 4.4. HVO and National Park staff reported frequent ground shaking, and damage to roads and buildings. Phreatic explosions had ejected blocks up to 60 cm in diameter that were found in the parking lot a few hundred meters from Halema’uma’u Crater. Ash plume heights varied, but generally rose no higher than 1.2 km and drifted N. Lava continued to erupt from multiple vents at the NE end of the active fissure system at the Lower East Rift Zone (LERZ). Lava from fissure 17 advanced about 90 m. Weak spattering arose from fissure 18, and fissure 20 was again active.
At about 0415 on 17 May an explosive event (or a series of explosions) at Overlook Crater generated an ash plume that, according to the Washington VAAC, rose as high as 9.1 km (30,000 ft) a.s.l. and drifted NE. Ash fell in areas downwind, including in the Volcano Golf Course and Volcano Village. Subsequent gas, steam, and ash emissions rose to 3.7 km (12,000 ft) a.s.l. and drifted SW. Fissure 17 actively spattered, though its lava flow had nearly stalled. Fissures 18, 19, and 20 reactivated, and a new fissure (21) opened between fissures 7 and 3. A 50-100-m-wide depression with cracks formed parallel to the fissures between Highway 130 and Lanipuna Gardens, into which pahoehoe lava flowed from fissures 20 and 21. Fissure 22 opened just downrift of fissure 19.
On 18 May a robust gas-and-steam plume rose from Overlook Crater, punctuated by several minor ash emissions. At 2358 a short-lived explosion generated an ash plume that rose up to 3 km (10,000 ft) a.s.l. and drifted SW. Spattering continued from fissures 15, 17, 18, 20, 21, and 22, with pahoehoe lava flows being erupted from fissures 17, 18, and 20. Large fountains at fissure 17 ejected bits of spatter 100 m high. Lava flows from fissure 18 traveled almost 1 km SE, and a flow from fissure 15 crossed Pohoiki Road. A fast-moving lava flow (275-365 m per hour) emerged from fissure 20 and traveled SE, across Pohoiki Road. Gas emissions remained elevated in areas downwind of the fissure system; air quality was poor from gas emissions as well as smoke from burning vegetation. Earthquake locations had not moved farther downrift in the previous few days.
Small ash emissions from Overlook Crater occurred intermittently on 19 May. The eruption of lava and ground cracking in the area of Leilani Estates subdivision continued. Fissure 17 was weakly active after fountaining earlier in the day. Fissures 16-20 merged into a continuous line of spatter and fountaining; flows from this fissure 20 complex flowed 275 m/hour S. Two of the flows joined less than a 1.6 km from the ocean and continued to flow S between Pohoiki and Opihikao roads.
During 19-20 May there were two explosive eruptions from Overlook Crater, and several smaller ash emissions. Lava flows reached the ocean overnight (late on 19 May) along the SE Puna coast. On 20 May spatter was ejected from fissures 6 and 17, and fissure 20 produced significant lava flows. A ground crack opened under the E lava channel diverting lava into underground voids. Gas emissions tripled as a result of the voluminous eruptions from fissure 20. Photos take in the afternoon showed two ocean entries along approximately 1 km of coastline.
A small explosion at Overlook Crater at 0055 on 21 May produced an ash plume that rose around 2.1 km (7,000 ft) a.s.l. and drifted SW. Several smaller emissions throughout the day ejected abundant ash. Robust steam-and-gas plumes also rose from the crater. Lava fountains from fissure 22 fed a channelized lava flow that entered the ocean N of MacKenzie State Park. Spattering occurred at fissures 6, 17, and 19. Small ash emissions from Overlook Crater continued on 22 May. Lava continued to enter the ocean, though by the afternoon only one entry was active. Most of the LERZ activity shifted to the middle part of the fissure system. The Aviation Color Code remained at Red and the Volcano Alert Level remained at Warning.
Geologic Summary. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) https://volcanoes.usgs.
Langila | New Britain (Papua New Guinea) | 5.525°S, 148.42°E | Summit elev. 1330 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 17-18 and 21-22 May ash plumes from Langila rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted WSW, W, and WNW.
Geologic Summary. Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/a
Merapi | Central Java (Indonesia) | 7.54°S, 110.446°E | Summit elev. 2910 m
PVMBG reported that a phreatic eruption at Merapi began at 0125 on 21 May and lasted for 19 minutes, generating an ash plume that rose 700 m above the crater and drifted W. A six-minute-long phreatic eruption began at 0938 and produced an ash plume that rose 1.2 km above the crater. Ashfall from both events was reported in areas 15 km downwind. A third event, detected at 1750, lasted three minutes and produced a plume of unknown height. After the events one volcano-tectonic earthquake and one tremor event were recorded. The seismicity along with increased phreatic events prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4).
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 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive 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 during historical time.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/
Piton de la Fournaise | Reunion Island (France) | 21.244°S, 55.708°E | Summit elev. 2632 m
OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 22 May. Flowing lava was mostly confined to tubes, though spatter was ejected 20-30 m above the highest-elevation (and most active) vent of the three. Lava was weakly ejected from the lowest-elevation vent. CO2 concentrations at the summit were high. Inflation continued to be detected. Tremor levels had increased around 15 May but then began to steadily decrease on 18 May. Observers noted a significant decrease in activity on 19 May at the highest-elevation vent, and by 22 May was quiet; the main cone continued to spatter.
Geologic Summary. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF) http://www.ipgp.fr/
Ongoing Activity
Agung | Bali (Indonesia) | 8.343°S, 115.508°E | Summit elev. 2997 m
PVMBG reported that at 1719 on 19 May an event at Agung generated an ash plume that rose 1 km above the crater rim and drifted SE. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone continued at a 4-km radius.
Geologic Summary. Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/
Aira | Kyushu (Japan) | 31.593°N, 130.657°E | Summit elev. 1117 m
JMA reported that there were 13 events and 20 explosions at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 14-21 May. Tephra was ejected as far as 1.1 km from the crater, and ash plumes rose as high as 2.7 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).
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 Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/
Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m
Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 16-22 May ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NW, W, and SW.
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, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. 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: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/a
Ebeko | Paramushir Island (Russia) | 50.686°N, 156.014°E | Summit elev. 1103 m
Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 12-14 May that sent ash plumes as high as 2.8 km (9,200 ft) a.s.l. Ash plumes drifted about 20 km SW on 13 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
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/
Fuego | Guatemala | 14.473°N, 90.88°W | Summit elev. 3763 m
INSIVUMEH reported that beginning at 1400 on 17 May a lahar descended the Seca (Santa Teresa) drainage on Fuego’s W flank. The lahar was 25 m wide, 1 m deep, and carried trees and blocks 1.5 m in diameter. During 19-21 May explosions occurred at a rate of 5-8 per hour, and generated ash plumes that rose almost 1 km and drifted 10-20 km S, SW, and W. Some explosions were accompanied by rumbling audible more than 30 km away, and shock waves that vibrated structures in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 200-300 m above the crater rim, and generated avalanches of material within the Seca, Ceniza (SSW), and Las Lajas (SE) drainages that reached vegetated areas. Ash fell in areas downwind including in Santa Sofía (12 km SW), Morelia, Panimaché I and II, and Finca Palo Verde. A lava flow 700-800 m long was active in the Ceniza drainage.
Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.
Karymsky | Eastern Kamchatka (Russia) | 54.049°N, 159.443°E | Summit elev. 1513 m
KVERT reported that during 13-15 May a thermal anomaly over Karymsky was identified in satellite images, as well as ash plumes drifting about 150 km SW on 14 May. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
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/
Kirishimayama | Kyushu (Japan) | 31.934°N, 130.862°E | Summit elev. 1700 m
The Tokyo VAAC reported that on 15 May ash plumes from Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, were identified in satellite images drifting S at an altitude of 7.6 km (25,000 ft) a.s.l. JMA noted that white plumes rose 100 m above the crater rim during 18-21 May. The Alert Level remained at 3 (on a scale of 1-5).
Geologic Summary. Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1700-m-high Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/
Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.
Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m
KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images during 13-14 May. Strong explosions began at 0315 on 15 May, and generated ash plumes that rose as high as 10.5 km (34,400 ft) a.s.l. The ash clouds lingered around Klyuchevskoy and surrounding volcanoes for about eight hours before gradually dissipating. Nighttime summit incandescence and a hot avalanche were noted. The Aviation Color Code was raised to Orange.
Geologic Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions 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/
Sabancaya | Peru | 15.787°S, 71.857°W | Summit elev. 5960 m
Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was comparable to the previous week; explosions averaged 30 per day during 14-20 May. Seismicity was dominated by long-period events and signals indicating emissions. Gas-and-ash plumes rose as high as 1.9 km above the crater rim and drifted N and NW. The MIROVA system detected nine thermal anomalies, and on 19 May the sulfur dioxide gas flux was high at 3,147 tons/day. The report noted that the public should not approach the crater within a 12-km radius.
Geologic Summary. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.
Sources: Instituto Geológico Minero y Metalúrgico (INGEMMET) http://www.
Instituto Geofísico del Perú (IGP) http://www.igp.gob.pe/
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images on 28 and 11-16 May. The Aviation Color Code remained at Orange.
Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most active volcanic structures. 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 dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. 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/
Sinabung | Indonesia | 3.17°N, 98.392°E | Summit elev. 2460 m
PVMBG reported that during 16-21 May gray-to-white plumes from Sinabung rose as high as 700 m above the crater rim and drifted in multiple directions. At 0900 on 20 May an event produced an ash plume that rose 700 m and drifted NW. An ash plume from an event later that day at 2122 rose 2.5 km and drifted W and NW. The Alert Level remained at 4 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions of 7 km on the SSE sector, 6 km in the ESE sector, and 4 km in the NNE sector.
Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/
Turrialba | Costa Rica | 10.025°N, 83.767°W | Summit elev. 3340 m
OVSICORI-UNA reported that an event at Turrialba at 0900 on 21 May generated a plume that rose to an unknown height due to poor visibility.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive edifice covers an area of 500 km2. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.
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