Smithsonian / USGS Weekly Volcanic Activity Report 10-16 February 2021

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Thu, 18 Feb 2021 12:40:24 -0700

5-5-5-5-5-5-5-5-5-5-5-5-5-5

From: "Kuhn, Sally" <KUHNS@xxxxxx>

Smithsonian / USGS Weekly Volcanic Activity Report

10-16 February 2021

Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)

URL: https://volcano.si.edu/reports_weekly.cfm

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

The Weekly Volcanic Activity Report is a cooperative project between the
Smithsonian's Global Volcanism Program and the US Geological Survey's
Volcano Hazards Program. Updated by 2300 UTC every Wednesday, these reports
are preliminary and subject to change as events are studied in more detail.
This is not a comprehensive list of all of Earth's volcanoes erupting
during the week, but rather a summary of activity at volcanoes that meet
criteria discussed in detail in the "Criteria and Disclaimers" section.
Carefully reviewed, detailed reports about recent activity are published in
issues of the Bulletin of the Global Volcanism Network.

Note that many news agencies do not archive the articles they post on the
Internet, and therefore the links to some sources may not be active. To
obtain information about the cited articles that are no longer available on
the Internet contact the source.

New Activity/Unrest

Etna  | Sicily (Italy)  | 37.748Â°N, 14.999Â°E  | Summit elev. 3320 m

INGV reported that Strombolian activity from all four of Etnaâ??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.

Geologic 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.

Source: Sezione di Catania - Osservatorio Etneo (INGV)
http://www.ct.ingv.it/

Merapi  | Central Java (Indonesia)  | 7.54Â°S, 110.446Â°E  | Summit elev.
2910 m

BPPTKG reported that the 2021 lava dome continued to grow just below
Merapiâ??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.

Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in
one of the world's most densely populated areas and dominates the landscape
immediately north of the major city of Yogyakarta. It is the youngest and
southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth
of Old Merapi during the Pleistocene ended with major edifice collapse
perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the
eroded older Batulawang volcano. Subsequent growth of the steep-sided Young
Merapi edifice, its upper part unvegetated due to frequent activity, began
SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying
growth and collapse of the steep-sided active summit lava dome have
devastated cultivated lands on the western-to-southern flanks and caused
many fatalities.

Sources: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi
(BPPTKG) http://www.merapi.bgl.esdm.go.id/;

Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
http://vsi.esdm.go.id/

Raung  | Eastern Java (Indonesia)  | 8.119Â°S, 114.056Â°E  | Summit elev.
3260 m

PVMBG reported that daily gray ash plumes rose as high as 2.5 km above
Raungâ??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.

Geologic 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) http://vsi.esdm.go.id/

Sarychev Peak  | Matua Island (Russia)  | 48.092Â°N, 153.2Â°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).

Geologic 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/index_eng.php

Ongoing Activity

Aira  | Kyushu (Japan)  | 31.593Â°N, 130.657Â°E  | Summit elev. 1117 m

JMA reported that during 8-15 February incandescence from Minamidake Crater
(at Aira Calderaâ??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).

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/jma/

Dukono  | Halmahera (Indonesia)  | 1.693Â°N, 127.894Â°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.

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.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml;

Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
http://vsi.esdm.go.id/

Ebeko  | Paramushir Island (Russia)  | 50.686Â°N, 156.014Â°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).

Geologic Summary. The flat-topped summit of the central cone of Ebeko
volcano, one of the most active in the Kuril Islands, occupies the northern
end of Paramushir Island. Three summit craters located along a SSW-NNE line
form Ebeko volcano proper, at the northern end of a complex of five
volcanic cones. Blocky lava flows extend west from Ebeko and SE from the
neighboring Nezametnyi cone. The eastern part of the southern crater
contains strong solfataras and a large boiling spring. The central crater
is filled by a lake about 20 m deep whose shores are lined with steaming
solfataras; the northern crater lies across a narrow, low barrier from the
central crater and contains a small, cold crescentic lake. Historical
activity, recorded since the late-18th century, has been restricted to
small-to-moderate explosive eruptions from the summit craters. Intense
fumarolic activity occurs in the summit craters, on the outer flanks of the
cone, and in lateral explosion craters.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/index_eng.php

Fuego  | Guatemala  | 14.473Â°N, 90.88Â°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), TaniluyÃ¡
(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 SofÃa, 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 SacatÃ©pequez. 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.

Geologic Summary. VolcÃ¡n 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.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/

Kanlaon  | Philippines  | 10.412Â°N, 123.132Â°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.

Geologic 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.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
http://www.phivolcs.dost.gov.ph/

Karymsky  | Eastern Kamchatka (Russia)  | 54.049Â°N, 159.443Â°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.

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/ivs/kvert/index_eng.php

Kavachi  | Solomon Islands  | 8.991Â°S, 157.979Â°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.

Geologic 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.

Sources: Sentinel Hub https://sentinel-hub.com/explore/sentinel-playground;

Culture Volcan https://laculturevolcan.blogspot.com/

Kilauea  | Hawaiian Islands (USA)  | 19.421Â°N, 155.287Â°W  | Summit elev.
1222 m

HVO reported that a vent on the inner NW wall of Kilaueaâ??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 â??plateâ?? 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.

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.gov/observatories/hvo/

Klyuchevskoy  | Central Kamchatka (Russia)  | 56.056Â°N, 160.642Â°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.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT)
http://www.kscnet.ru/ivs/kvert/index_eng.php;

Tokyo Volcanic Ash Advisory Center (VAAC)
http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html

Lewotolo  | Lomblen Island (Indonesia)  | 8.274Â°S, 123.508Â°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.

Geologic 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) http://vsi.esdm.go.id/

Pacaya  | Guatemala  | 14.382Â°N, 90.601Â°W  | Summit elev. 2569 m

INSIVUMEH reported that a during 9-10 February Strombolian explosions at
Pacayaâ??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 ConcepciÃ³n 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.

Geologic 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 AmatitlÃ¡n 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.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/

San Cristobal  | Nicaragua  | 12.702Â°N, 87.004Â°W  | Summit elev. 1745 m

The Washington VAAC reported that on 14 February an ash cloud from San
CristÃ³bal 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.

Geologic Summary. The San CristÃ³bal 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 CristÃ³bal (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 CristÃ³bal; it and the eroded Moyotepe volcano, 4 km NE of San
CristÃ³bal, are of Pleistocene age. VolcÃ¡n Casita, containing an elongated
summit crater, lies immediately east of San CristÃ³bal 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 CristÃ³bal, 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.

Source: Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html

San Miguel  | El Salvador  | 13.434Â°N, 88.269Â°W  | Summit elev. 2130 m

SNET stated that San Miguelâ??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.

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.

Source: Servicio Nacio

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End of Volcano Digest - 15 Feb 2021 to 18 Feb 2021 (#2021-16)
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