Environment

The Weekly Volcanic Activity Report: January 31


New activity/unrest was reported for 5 volcanoes between January 31 and February 6, 2018. During the same period, ongoing activity was reported for 10 volcanoes.

New activity/unrest: Fuego, Guatemala | Kadovar, Papua New Guinea | Karangetang, Siau Island (Indonesia) | Mayon, Luzon (Philippines) | San Miguel, El Salvador.

Ongoing activity: Aira, Kyushu (Japan) | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Nevados de Chillan, Chile | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Turrialba, Costa Rica.

New activity/unrest

Fuego, Guatemala

14.473°N, 90.88°W, Summit elev. 3763 m

INSIVUMEH reported that the first Strombolian eruption at Fuego in 2018 began on 31 January, after a thermal anomaly was detected in satellite images the day before. Explosions produced ash plumes that rose 1.5 km above the crater and drifted 20 km SW. Lava fountains rose 300-500 m, and fed lava flows that traveled 800 m W in the Seca (Santa Teresa) drainage and 600 m in Las Lajas (SE) and Honda (E) drainages. On 1 February the eruption style changed to Vulcanian. Pyroclastic flows mainly descended the Seca, Trinidad (S), Las Lajas, and Honda drainages. Ash plumes from explosions rose 3.2 km and drifted more than 60 km NE, SW, and W. Ashfall was recorded in areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), Ciudad Vieja (13.5 km NE), Antigua Guatemala (18 km NE), and W and SW Ciudad de Guatemala. CONRED reported that 2,880 people were evacuated. At 1630 INSIVUMEH noted that the Strombolian-Vulcanian eruption phase had finished, 20 hours after it had begun. Explosions continued, generating ash plumes that rose just under 1 km and drifted 15 km SW.

On 2 February there were 3-5 weak explosion recorded per hour, with ash plumes rising 750 m and drifting 5-8 km W, SW, and S. Shock waves and rumbling were noted, and the lava flows remained visible. During 4-5 February ash plumes from explosions (about 5 per hour) produced ash plumes that rose 700 m and drifted W and SW. Incandescent material was ejected 200 m above the crater, causing weak avalanches of material around the crater area and in some vegetated areas.

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.

Kadovar, Papua New Guinea

3.608°S, 144.588°E, Summit elev. 365 m

RVO reported that the eruption at Kadovar continued during 31 January-1 February at a low level. Sulfur dioxide emissions and seismicity had both decreased. Dense white vapor plumes rose 100 m from Main Crater and drifted SE. Continuous but dull glow emanated from the crater. The lava dome at the SE Coastal Vent continued to grow. A new lobe 20-30 m long grew out from the seaward side of the dome boundary, channeled by levees which had developed on the sides of the dome. White steam plumes rose 100 m above the island and drifted SE. At 1830 on 1 February a collapse of the N part of the dome produced a gray plume, vigorous steaming at the collapse site, and nighttime incandescence. The main part of the dome had bulged up, and a valley developed in between the dome and the island’s flank.

Geologic 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.

Karangetang, Siau Island (Indonesia)

2.781°N, 125.407°E, Summit elev. 1797 m

In a VONA issued on 2 February, PVMBG reported an eruption at Karangetang, characterized by crater incandescence and an ash plume that rose 600 m. The Aviation Color Code was raised from Unassigned to Yellow.

Geologic summary: Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia’s most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Mayon, Luzon (Philippines)

13.257°N, 123.685°E, Summit elev. 2462 m

PHIVOLCS reported that during 31 January-6 February daily activity at Mayon continued to be characterized by lava effusion from the summit crater, rockfalls, pyroclastic flows (31 January-1 February), ash and steam emissions, advancing lava flows on the flanks, and weak and sporadic lava fountains. Numerous rockfall events were generated by the growing and collapsing summit lava dome and from the front and margins of advancing lava flows. On 31 January pyroclastic flows traveled as far as 2 km in the Mi-isi (S), Basud (E), and Bonga (SE) drainages. White-to-light-gray ash plumes generally rose to low heights, though five events generated ash plumes that rose as high as 1 km above the crater rim. An event on 2 February also produced an ash plume that rose 1 km. The first of two lava fountaining events on 4 February lasted sporadically for 114 minutes, generated an ash plume that rose 500 m, and produced booming sounds heard within a 10-km radius. During 5-6 February high volumes of effused lava extended the lava flows in the Mi-isi, Bonga-Buyuan, and Basud drainages to 3.2, 4.5, and 3 km, respectively. The Alert Level remained at 4 (on a 0-5 scale) and the public was warned to remain outside of the Danger Zone defined as an area within an 8-km radius.

Geologic 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.

San Miguel, El Salvador

13.434°N, 88.269°W, Summit elev. 2130 m

On 2 February SNET reported that seismicity at San Miguel was decreasing, along with a decrease in emissions. RSAM values fluctuating between 63 and 114 units; normal values are between 50 and 150. Small pulses of gas near the crater rim were visible.

Geologic 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

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported that very small events occurred at Minamidake crater (at Aira Caldera’s Sakurajima volcano) on 1 and 3 February. Crater incandescence from the summit crater was visible during 2-3 February. 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.

Cleveland, Chuginadak Island (USA)

52.825°N, 169.944°W, Summit elev. 1730 m

AVO reported that unrest at Cleveland continued during 31 January-6 February, though nothing significant was detected in seismic or infrasound data. Moderately elevated surface temperatures were identified in satellite images during 30-31 January; cloudy weather prevented observations the rest of the week. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geologic summary: Beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited, dumbbell-shaped Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Cleveland is joined to the rest of Chuginadak Island by a low isthmus. The 1730-m-high Mount Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name for Mount Cleveland, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

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 31 January-6 February ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NE, E, and ESE.

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.

Ebeko, Paramushir Island (Russia)

50.686°N, 156.014°E, Summit elev. 1103 m

Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 26-27 and 29-31 January generated ash plumes that rose as high as 2.5 km (8,200 ft) a.s.l. Ash fell in Severo-Kurilsk on 29 January. 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.

Karymsky, Eastern Kamchatka (Russia)

54.049°N, 159.443°E, Summit elev. 1513 m

KVERT reported that an ash plume from Karymsky was identified in satellite images drifting 80 km NE on 27 January. 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.

Kilauea, Hawaiian Islands (USA)

19.421°N, 155.287°W, Summit elev. 1222 m

During 31 January-6 February HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Webcams recorded incandescence from a small lava pond in a pit on the W side of Pu’u ‘O’o Crater. Surface lava flows were active above and on the pali, and on the coastal plain.

Geologic 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.

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 growth of the lava dome in Nevados de Chillán’s Nicanor Crater was 2,540 m3/day, determined by photos taken during overflights on 23 and 31 January. The total volume of the lava dome was an estimated 106,700 m3. A small area of deposits from collapses of the dome walls was observed. Temperatures on the surface of the dome were 305 and 480 degrees Celsius, mainly from a crack which generated the explosions. A larger explosion from a possible partial dome collapse was recorded at 1202 on 2 February, generating a gas-and-ash plume that rose about 2.5 km above the crater rim. Shock waves from the explosion were reported in the community of Las Trancas (10 km) and at the Gran Hotel Termas de Chillan (5 km). Explosive activity continued through 6 February. 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.

Geologic 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.

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 decreased compared to the previous week; there was an average of 22 explosions recorded per day during 29 January-4 February. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 3.5 km above the crater rim and drifted 50 km NW, SW, and S. The MIROVA system detected two thermal anomalies. The sulfur dioxide flux was high, at 3,388 tons per day on 31 January. The report noted that the public should not to 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.

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 on 1 February. 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 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.

Turrialba, Costa Rica

10.025°N, 83.767°W, Summit elev. 3340 m

OVSICORI-UNA reported that an event at Turrialba at 0830 on 5 February generated a plume that rose 200 m above the crater rim and drifted SW. An event at 0730 on 6 February generated an ash plume that rose 1 km and drifted SW. Ashfall was reported in Goicoechea and Heredia.

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 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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