The Weekly Volcanic Activity Report: January 10 - 16, 2018

The Weekly Volcanic Activity Report: January 10 - 16, 2018

New activity/unrest was reported for 4 volcanoes between January 10 - 16, 2018. During the same period, ongoing activity was reported for 8 volcanoes.
New activity/unrest: Kadovar, Papua New Guinea | Mayon, Luzon (Philippines) | Nevados de Chillan, Chile | San Miguel, El Salvador.
Ongoing activity: Agung, Bali (Indonesia) | Aira, Kyushu (Japan) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan) | 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 23:00 UTC every Wednesday, notices of volcanic activity posted 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. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New activity/unrest

Kadovar, Papua New Guinea

3.608°S, 144.588°E, Summit elev. 365 m
According to Brandon Buser, just after eruption plumes started rising from a vent on the SE side of Kadovar on 5 January boats from a village on the mainland (22 km SW) and from Bam (25 km E) were sent to the island to evacuate residents. The entire population of the island (about 500 people according to a news article citing the Red Cross) was evacuated by the boats and numerous canoes to Blup Blup (15 km N). Activity escalated around midnight. The next day, at a distance of 65 km, Buser and others saw ash emissions rising from Kadovar, and at about 24 km away from the island they experienced ashfall. As they were circling the island a large event sent a large plume hundreds of feet into the air and ejected large boulders into the ocean. During another visit on 8 January Buser noted two new eruptive vents, ashfall covering everything on the village side, and wet falling ash.
RVO reported that activity significantly escalated on 12 January characterized by a large blast of a substantial amount of material and “big” glowing red rocks directed to the S; the report noted that the blast was the only one reported to date. Observers on Blup Blup saw incandescence emanating from either the summit or an area out of view on the S flank. Large amounts of sulfur dioxide had been detected since 8 January, and continued to be emitted. A fracture had previously been reported on 6 January extending from the summit to the coast. When seen on 12 January, the fracture was wider and vigorous steaming was occurring at sea level. Ash plumes drifted tens of kilometers W and NW. RVO noted that the displaced villagers were getting transferred to the mainland, along with islanders from Bam, due to the relatively close proximity to the eruption plus the logistics of supplying them.
Five newly-named vents were observed during an overflight conducted on 13 January: Main Crater, Western vent, and Southern vent (all three are at the summit), the SE Coastal vent, and the Southern Coastal vent. Sometimes voluminous steam and dense gray plumes rose 1 km above the Main Crater. The emissions obscured views of Southern and Western vents. The SE Coastal Vent was very active, emitting dense white steam plumes 600 m a.s.l. A possible lava dome was at the base of the plumes but showed no evidence of incandescence. The Southern Coastal Vent, located where the original fractures entered the sea, was inactive.
Geological summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. Kadovar is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. The village of Gewai is perched on the crater rim. A 365-m-high lava dome forming the high point of the andesitic volcano fills an arcuate landslide scarp that is open to the south, and submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. No certain historical eruptions are known; the latest activity was a period of heightened thermal phenomena in 1976.

Mayon, Luzon (Philippines)

13.257°N, 123.685°E, Summit elev. 2462 m
PHIVOLCS reported that a phreatic eruption at Mayon was detected at 1621 on 13 January, generating an ash plume that rose 2.5 km and drifted SW. The seismic network recorded the event for 1 hour and 47 minutes. Trace amounts of ash fell in Barangays Anoling (4 km S), Sua (6 km SSW), Quirangay (6 km SSW), Tumpa (7 km SW), Ilawod (10 km SSW), and Salugan (9 km SSW) of Camalig, and in Barangays Tandarora (10 km SW), Maninila (18 km S), and Travesia (10 km SW) in Guinobatan. A sulfur odor was noted by residents of Camalig. Rumbling sounds were heard by residents in Anoling. The Alert Level was raised to 2 (on a 0-5 scale). Faint crater incandescence was first observed at 2216. A phreatic eruption began at 0849 on 14 January and lasted about five minutes, and another was detected at 1143 and lasted 15 minutes. Steam-and-ash plumes from both events rose from the crater but were mostly obscured by weather clouds. Anoling residents noted rumbling sounds and a sulfur odor, and minor amounts of ash fell in Camalig.
On 14 January PHIVOLCS raised the Alert Level to 3, noting a marked increase in activity characterized by three phreatic eruptions and 158 rockfall events between 1621 on 13 January and 1925 on 14 January. Bright crater incandescence was evident, signifying growth of a new lava dome and lava beginning to flow on the S flank. The report reminded residents to stay away from the 6-km-radius Permanent Danger Zone (PDZ) and the 7-km Extended Danger Zone (EDZ) on the S flank.
Three collapses of material occurred on 15 January, producing rockfall or small-volume pyroclastic density currents. They were detected by the seismic network at 0941, 1005, and 1107 and lasted five, seven, and eight minutes, respectively. The first two events appeared to have been from collapses of the lava-flow front and generated ash plumes that drifted SW and ashfall in multiple Barangays including Travesia, Muladbucad Grande (8 km W), Maninila, and Masarawag (5 km W) of the Guinobatan municipality, and several Barangays in the Camalig municipality. An ash plume from the third event rose about 1 km above the crater and drifted WSW.
During 15-16 January the new lava dome in the summit crater continued to effuse. Lava flows advanced 2 km down the Miisi drainage (S), and a small-volume flow was emplaced on the upper slopes of the Bonga drainage (SSE). The seismic network recorded multiple events including short-duration lava fountaining, 75 lava-collapse events corresponding to rockfalls along the front and margins of advancing lava, and short pyroclastic flows in the Miisi drainage. Ash plumes from collapse events in the summit crater produced ash plumes that rose 2 km and caused ashfall in Camalig, Guinobatan, and Polangui.
Geological summary: Beautifully symmetrical Mayon volcano, which rises to 2462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions at this basaltic-andesitic volcano date back to 1616 and range from strombolian to basaltic plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1200 people and devastated several towns.

Nevados de Chillan, Chile

36.868°S, 71.378°W, Summit elev. 3180 m
Servicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) reported that during an overflight of Nevados de Chillán's Volcán Arrau dome complex on 9 January scientists observed a new lava dome in the active central crater, corresponding to a new fissure first identified on 21 December 2017. Gas and water vapor rose from the fissure going across the dome surface, and the temperature of the surface was about 480 degrees Celsius. The Alert Level remained at Yellow, the middle level on a three-color scale, and the public was reminded not to approach the craters within a 4-km radius.
Geological summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.

San Miguel, El Salvador

13.434°N, 88.269°W, Summit elev. 2130 m
SNET reported that at 1653 on 14 January and 1615 on 15 January gas-and-ash plumes from San Miguel rose no more than 300 m above the crater rim and dispersed SW. The report noted that prior to both emissions seismicity decreased and then suddenly increased.
Geological summary: The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit, also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the N, NE, and SE sides. The SE-flank flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.

Ongoing activity

Agung, Bali (Indonesia)

8.343°S, 115.508°E, Summit elev. 2997 m
PVMBG reported that during 10-16 January gray-and-white plumes generally rose as high as 500 m above Agung’s crater rim and drifted S, SE, and E. An event at 1754 on 11 January produced an ash plume that rose 2.5 km above the crater rim and drifted NE (likely causing ashfall in areas downwind), and another event at 0723 on 15 January generated an ash plume that rose 2 km. As of 11 January BNPB estimated that 53,207 evacuees were spread out in 233 shelters. The Alert Level remained at 4 (on a scale of 1-4) and the exclusion zone continued at a 6-km radius.
Geological 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.

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported that an explosive event occurred at Minamidake crater (at Aira Caldera’s Sakurajima volcano) at 1020 on 10 January, ejecting material 500-700 m from the crater. Weather clouds obscured views of the emissions. There were three events, two of which were explosive, detected during 12-15 January. The explosions ejected material as far as 500 m from the crater and produced plumes that rose as high as 1.5 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).
Geological 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.

Kilauea, Hawaiian Islands (USA)

19.421°N, 155.287°W, Summit elev. 1222 m
During 10-16 January HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Surface lava flows were active above and on the pali, and on the coastal plain.
Geological summary: Kilauea volcano, which overlaps the east 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 sq km, destroying nearly 200 houses and adding new coastline to the island.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Summit elev. 4754 m
Based on satellite observations KVERT reported that gas-and-steam plumes from Klyuchevskoy contained some ash and drifted about 160 km NW and E during 5-6 and 8-10 January. A weak thermal anomaly was visible on 6 and 8 January. The Aviation Color Code remained at Orange.
Geological 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.

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 similar to the previous week; there was an average of 57 explosions recorded per day during 8-14 January. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 2.5 km above the crater rim and drifted 50 km NW and SW. The MIROVA system detected three thermal anomalies. The sulfur dioxide flux was high, at 2,071 tons per day on 12 January. The report noted that the public should not to approach the crater within a 12-km radius.
Geological 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.

Sheveluch, Central Kamchatka (Russia)

56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 5-12 January. Ash plumes from explosions which began at 1035 on 10 January rose to altitudes of 10-11 km (32,800-36,100 ft) a.s.l. and drifted about 900 km E during 10-11 January. KVERT briefly raised the Aviation Color Code to Red on 10 January, and then lowered it back to Orange later that day.
Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km 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.

Suwanosejima, Ryukyu Islands (Japan)

29.638°N, 129.714°E, Summit elev. 796 m
Based on JMA notices and satellite data, the Tokyo VAAC reported that on 15 January an eruption at Suwanosejima produced a plume that rose 1.8 km (6,000 ft) a.s.l. and drifted NW.
Geological summary: The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed 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 the horseshoe-shaped Sakuchi caldera, which extends 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.

Turrialba, Costa Rica

10.025°N, 83.767°W, Summit elev. 3340 m
OVSICORI-UNA reported that an event at Turrialba at 0400 on 15 January generated a plume of unknown height due to weather conditions. Ashfall was reported in areas N of Pacayas (Pinos, Buenos Aires, and Santa Rosa de Oreamuno) and a sulfur odor was noted in Santa Rosa de Oreamuno.
Geological 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 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. 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: GVP

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