The Weekly Volcanic Activity Report: February 10 - 16, 2021

The Weekly Volcanic Activity Report: February 10 - 16, 2021

New activity/unrest was reported for 4 volcanoes from February 10 to 16, 2021. During the same period, ongoing activity was reported for 19 volcanoes.

New activity/unrest: Etna, Sicily (Italy) | Merapi, Central Java (Indonesia) | Raung, Eastern Java (Indonesia) | Sarychev Peak, Matua Island (Russia).

Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Kanlaon, Philippines | Karymsky, Eastern Kamchatka (Russia) | Kavachi, Solomon Islands | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Lewotolo, Lomblen Island (Indonesia) | Pacaya, Guatemala | San Cristobal, Nicaragua | San Miguel, El Salvador | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Soufriere St. Vincent, St. Vincent | Suwanosejima, Ryukyu Islands (Japan) | Taal, Luzon (Philippines) | Villarrica, Chile.

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, 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.

New activity/unrest

Etna, Sicily (Italy)

37.748°N, 14.999°E, Summit elev. 3320 m

INGV reported that Strombolian activity from all four of Etna’s summit craters, the Southeast Crater (SEC), Northeast Crater (NEC), Bocca Nuova (BN), and Voragine (VOR), was visible during 8-14 February. The frequency and intensity of explosions at SEC were variable; almost continuous strong explosions originated from two vents in the E part of the top of the cone. Tephra accumulated near the top of the cone and rolled several tens of meters down the flanks. Minor ash emissions rapidly dispersed. Less-intense Strombolian activity occurred at the S vent (also called the saddle vent). Intra-crater Strombolian activity at NEC sometimes produced nighttime crater incandescence. The activity at BN sometimes ejected coarse material beyond the crater rim, and rare emissions that had diffuse ash content. The the VOR Strombolian explosions ejected material that sometimes rose above the crater rim and generated diffuse ash emissions.

During the morning of 15 February explosive activity at SEC gradually intensified. Activity originated from the E vents but sometimes intense explosions occurred at the saddle vent. A significant increase in tremor amplitude began at 1700. Tremor amplitude waned at 2100, the same time that explosive activity decreased. At 1700 on 16 February lava began advancing down the E flank of SEC. Part of the cone collapsed at 1705 and generated a pyroclastic flow that traveled 1.5 km along the W wall of the Valle de Bove. An ash plume rapidly dispersed to the S. Explosive activity at SEC increased and lava fountaining began at 1710. Ash clouds drifted S. Lava flows advanced into the Valle de Bove, reaching an elevation of 2,000 m by 1759 at the latest. Lapilli, 1 cm in diameter, was reported in Nicolosi (16 km S) and Mascalucia (19 km S), and ash and lapilli fell in Catania (29 km SSE). Ashfall was also reported in Syracuse, 60-80 km SSE. Another lava flow advanced N into the Valle del Leone. Lava fountains were about 500 m tall, possibly as tall as 600 m. Tremor amplitude began to decrease at 1750 and lava fountains ceased around 1800. Lava effusion from SEC gradually diminished; the flow in the Valle de Bove was a few kilometers long and smaller flows that had traveled N and S reached an elevation of 2,900. Strombolian activity persisted at SEC overnight during 16-17 February and ceased at 0715 on 17 February. Explosions at VOR were sporadic.

Geological summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Merapi, Central Java (Indonesia)

7.54°S, 110.446°E, Summit elev. 2910 m

BPPTKG reported that the 2021 lava dome continued to grow just below Merapi’s SW rim during 5-11 February. The lava-dome volume was an estimated 295,000 cubic meters on 11 February, with a growth rate of about 48,900 cubic meters per day. Incandescent avalanches of material were occasionally visible; they traveled 700 m SW in the upper parts of the Krasak and Boyong drainages during 9-10 February. Weather conditions prevented visual observations of the lava dome in the summit crater. Seismicity was higher than the previous week. Electronic Distance Measurement (EDM) data showed no notable deformation. The Alert Level remained at 3 (on a scale of 1-4), and the public were warned to stay 5 km away from the summit.

Geological 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.

Raung, Eastern Java (Indonesia)

8.119°S, 114.056°E, Summit elev. 3260 m

PVMBG reported that daily gray ash plumes rose as high as 2.5 km above Raung’s summit during 10-16 February. Ash plumes were sometimes dense and drifted N, NE, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Geological summary: Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.

Sarychev Peak, Matua Island (Russia)

48.092°N, 153.2°E, Summit elev. 1496 m

KVERT reported that a thermal anomaly over Sarychev Peak was identified in satellite images during 5-12 February. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale).

Geological summary: Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5-km-wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows, prior to activity in 2009, had descended in all directions, often forming capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760s and include both quiet lava effusion and violent explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows that reached the sea.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that during 8-15 February incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was often visible nightly. One explosion and five eruptive events generated eruption plumes that rose 1.4-1.5 km above the crater rim and ejected bombs 800-1,100 km away from the crater. The sulfur dioxide emission rate was high, at 2,500 tons per day on 9 February. 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.

Dukono, Halmahera (Indonesia)

1.693°N, 127.894°E, Summit elev. 1229 m

Based on satellite and wind model data and information from PVMBG, the Darwin VAAC reported that during 12-13 February ash plumes from Dukono rose to 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted E. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Geological 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

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 29 January and 1-2 February that sent ash plumes to 3.6 km (11,800 ft) a.s.l. and drifted in multiple directions. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological 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.

Fuego, Guatemala

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

INSIVUMEH reported that continuous avalanches of material at Fuego during 9-10 February descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Las Lajas (SE), and Honda drainages. There were 8-12 explosions per hour, generating ash plumes that rose as high as 1.1 km above the crater rim that drifted 15-20 km W and SE. Ashfall was reported in areas downwind including Santa Sofía, Panimache, Morelia, and Yucales, and shockwaves were audible up to 15 km away. The number of explosions increased to 3-6 per hour during 11-12 February. Ash-and-gas plumes rose to 1.1 km and drifted W and SW, causing ashfall in Sangre de Cristo, Palo Verde, and Yepocapa. Shock waves were felt by nearby residents. Avalanches of material descended the flanks, reaching vegetated areas.

During 12-13 February incandescent material was ejected 200 m above the summit and shock waved vibrated local structures. A lava flow had traveled 1 km down the Ceniza drainage, spalling blocks from the flow front that reached vegetated areas. By 14 February the lava flow had lengthened to 1.5 km and a lava flow in the Seca drainage traveled 500 m. During 1020-1023 a series of pyroclastic flows traveled several hundred meters down the Ceniza. Ash plumes from explosions rose 850 m and drifted NE, E, and SE, and caused ashfall in Alotenango, El Porvenir, and Finca La Reunion, in the department of Sacatépequez. During 14-15 February explosions ejected incandescent material 100 m above the summit and rattled nearby structures. Ash plumes rose as high as 450 m and drifted short distances E. Lava flows remained active; they were 800 and 200 m long in the Ceniza and Seca drainages, respectively. Block avalanches from the lava-flow fronts reached vegetated areas.

The lava effusion rate had steadily decreased during the late morning of 15 February. During the afternoon explosions, occurring at a rate of 14-30 per hour, produced ash plumes that rose 850-1,050 m above the summit and drifted as far as 50 km E, NE, and N. Ash fell in Porvenir and Alotenango. Activity continued to decrease through the day, characterized by a reduction in the explosion rate, less intense summit incandescence, and low RSAM values. INSIVUMEH declared an end to the effusive eruption phase. Explosions (12-14 per hour) generated ash plumes that rose over 1 km and drifted 130 km N, NE, and E.

Geological summary: Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. 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 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.

Kanlaon, Philippines

10.412°N, 123.132°E, Summit elev. 2435 m

PHIVOLCS reported slightly increased seismic activity and volcanic gas flux at Kanlaon. The seismic network recorded 28 volcanic earthquakes during 11-13 February with local magnitudes between 0.7 and 2.2. They were located at shallow depths around 10 km across the N to E portions of the edifice. The sulfur dioxide emission rate on 13 February was 1,130 tonnes per day, the highest value recorded this year; sulfur dioxide emissions had been higher than background levels of 300 tonnes/day since June 2020. Ground deformation data from continuous GPS and tilt measurements indicated slight inflation of the lower and middle flanks since June 2020. Increased seismic activity continued through 16 February; from 0800 on 14 February to 0800 on 16 February there were a total of 59 earthquakes. The Alert Level remained at 1 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone.

Geological summary: Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros. The massive andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that activity at Karymsky had decreased; strong explosions were last observed on 2 January and a thermal anomaly was last detected in satellite images on 5 February. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) on 11 February and then lowered to Green, the lowest level, on 16 February. Gas-and-steam emissions persisted.

Geological 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.

Kavachi, Solomon Islands

8.991°S, 157.979°E, Summit elev. -20 m

Satellite data showed discolored water around and to the SW of Kavachi on 25 January. Discolored water was not obviously visible in 20 January images; weather clouds prevented views of the area in images through 14 February.

Geological summary: Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is one of the most active submarine volcanoes in the SW Pacific, located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi ("Kavachi's Oven"), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

Kilauea, Hawaiian Islands (USA)

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

HVO reported that a vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to supply the lava lake during 10-16 February. The western part of the lake deepened from 215 m to around 217 m and the lake surface actively overturned at “plate” boundaries. The W end of the lava lake was perched by 3 m above the distal margin of recent overflows. A series of surficial cracks separated the W part of the lake from the stagnant E part. Lava spillovers just N of the inlet of lava sporadically flowed around the NW margin of the perched lake. Gas jetting at two locations above the W vents and two bursts of spatter were observed during 9-10 February. The sulfur dioxide emission rate was 1,600 and 1,100 tons/day on 10 and 12 February, respectively. During 15-16 February a few lava flows were visible along the N and E margins of the E part of the lake.

Geological 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.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Summit elev. 4754 m

KVERT reported that activity at Klyuchevskoy notably decreased, with the eruption likely ending on 8 Febryary. The temperature of the thermal anomaly identified in satellite images abruptly dropped on 7 February, and the magnitude of volcanic tremor decreased during 7-8 February and continued to decline through 12 February. Strombolian activity was not visible at night during 11-12 February. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) on 12 February.

The Tokyo VAAC reported that re-suspended ash was identified in satellite images during 12-13 February. On 15 February an ash plume rose to 5.2 km (17,000 ft) a.s.l. and drifted NE.

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.

Lewotolo, Lomblen Island (Indonesia)

8.274°S, 123.508°E, Summit elev. 1431 m

PVMBG reported that the eruption at Lewotolo continued during 9-15 February. Gray-and-white ash plumes rose 400-1,000 m above the summit and drifted E and SE. Strombolian explosions ejected material 500 m SE on 13 February. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km away from the summer crater.

Geological summary: The Lewotolo (or Lewotolok) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano's high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater.

Pacaya, Guatemala

14.382°N, 90.601°W, Summit elev. 2569 m

INSIVUMEH reported that a during 9-10 February Strombolian explosions at Pacaya’s Mackenney Crater ejected material 200-300 high and away from the crater. Ash clouds occasionally rose as high as 650 m and drifted 10 km W and SW. A 1.3-km-long lava flow was active on the S flank; block avalanches from the front of the lava flow descended 200 m. Activity increased around 1600 on 10 February. Strombolian explosions ejected incandescent material 500 m above the crater rim and produced gas-and-ash plumes that drifted W. Ashfall was reported in the villages of El Patrocinio (about 5 km W) and El Rodeo (4 km WSW). During 11-12 February material was ejected 300-500 m above the crater. Ash plumes rose 950 m and drifted N, causing ashfall in San Francisco de Sales (5 km N), San Jose Calderas, and Concepción el Cedro (9 km NNW).

Seismic data recorded pulses of increased activity during the morning of 12 February and again around 1400 on 13 February. Explosions ejected material 300-500 m above the crater. Ash-and-gas plumes rose almost 500 m and drifted 6 km W, N, and NE, causing ashfall in Santa Elena Barillas (6 km ENE), Mesillas Bajas (5 km NE), and Mesillas Altas. Another pulse of activity was recorded at 1145 on 14 February. Material was ejected as high as 250 m. Ash plumes rose less than 400 m and drifted 5 km E. A 650-m-long lava flow in the SSW flank was active on 15 February. Explosions continued to ejected material as high as 250 m above the vent.

Geological summary: Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

San Cristobal, Nicaragua

12.702°N, 87.004°W, Summit elev. 1745 m

The Washington VAAC reported that on 14 February an ash cloud from San Cristóbal rose to 2.3 km (7,500 ft) a.s.l. and drifted SW based on satellite data, webcam images, and weather models. A thermal anomaly was also identified.

Geological summary: The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km NE of San Cristóbal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.

San Miguel, El Salvador

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

SNET stated that San Miguel’s seismic network recorded long-lasting and continuous periods of volcanic tremor that began on 7 February and continued through 14 February. Discrete earthquakes from minor rock fracturing were also detected. RSAM values fluctuated between 25 and 75 units, below normal values around 150 units.

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.

Source: GVP


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