Smithsonian / USGS Weekly Volcanic Activity Report 3-9 February 2021

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Wed, 10 Feb 2021 12:44:00 -0700

2-2-2-2-2-2-2-2-2-2-2-2-2

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

Smithsonian / USGS Weekly Volcanic Activity Report

3-9 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)  | Semisopochnoi, United States

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), the Northeast Crater (NEC), Bocca
Nuova (BN), and Voragine (VOR), was visible during 1-7 February; the last
time that had occurred was during 1998-1999. The strongest and almost
continuous Strombolian explosions at SEC originated from two vents in the E
part of the top of the cone. Tephra accumulated near the top of the cone
and rolled down the flanks. Minor ash emissions rapidly dispersed.
Less-intense Strombolian activity occurred at the S vent. Intra-crater
Strombolian activity at NEC sometimes produced nighttime crater
incandescence. Strombolian activity at BN sometimes ejected coarse material
beyond the crater rim, and rare ash emissions that had diffuse ash content.
On 5 February scientists observed explosions from three vents at the bottom
of the crater that had formed cinder cones. Nearby was another cone that
occasionally produced dense emissions that rapidly dispersed. Strombolian
activity at VOR ejected material that sometimes rose above the crater rim
and generated diffuse ash emissions. On 5 February lava flowed into BN,
overlapping flows from the previous week.

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 29 January-4 February. One pyroclastic flow
descended the SW flank as far as 600 m. The 2021 lava dome volume was an
estimated 117,400 cubic meters on 4 February, with a growth rate of about
12,600 cubic meters per day. A comparison of photos taken on 21 January and
4 February showed that the morphological changes in the summit area were
attributed to the growth of the 2021 lava dome as well as from a new dome
slowly growing in the summit crater. Electronic Distance Measurement (EDM)
data showed no notable deformation. Seismic activity was lower than the
previous week. BNPB noted that a total of 537 people remained evacuated
(190 people from Sleman Regency and 347 from Klaten) as of 3 February. 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/;

Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/;

Detik News
https://news.detik.com/berita-jawa-tengah/d-5363189/gunung-merapi-kini-punya-2-kubah-lava?_ga=2.208545426.1624108119.1612808963-14950811.1611700211

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 1 km above
Raungâ??s summit and drifted S and E during 3-6 February. Ash plumes rose
1.2-2 km above the summit during 7-9 February and drifted SE and E.
Incandescence from the crater was often seen reflected in the emissions,
and rumbling and roaring was sometimes heard. 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 the eruption at Sarychev Peak continued during 29
January-5 February, characterized by lava effusion from the carter onto the
N flank. A thermal anomaly was identified in satellite images on 29 January
and 1 February; weather clouds prevented observations on the other days.
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

Semisopochnoi  | United States  | 51.93Â°N, 179.58Â°E  | Summit elev. 1221 m

AVO reported that a 6 February satellite image of Semisopochnoi showed
small ash deposits extending in a narrow strip less than 3 km N of North
Cerberus Crater. The deposits were likely the result of a small explosions
that occurred during the previous week. Steam emission obscured view of the
summit crater. The Aviation Color Code and the Volcano Alert Level were
raised to Yellow/Advisory. A second ash deposit, similar to the first, was
visible in a satellite image on 7 February. This deposit extended at least
3 km NE of North Cerberus Crater. Weather clouds obscured views of the S
side of the volcano. The report noted that the ash plumes associated with
the deposits had not been observed; they likely rose less than 3 km (10,000
ft) a.s.l. and were short lived. The Aviation Color Code and the Volcano
Alert Level were raised to Orange/Watch.

Geologic Summary. Semisopochnoi, the largest subaerial volcano of the
western Aleutians, is 20 km wide at sea level and contains an 8-km-wide
caldera. It formed as a result of collapse of a low-angle, dominantly
basaltic volcano following the eruption of a large volume of dacitic
pumice. The high point of the island is Anvil Peak, a double-peaked
late-Pleistocene cone that forms much of the island's northern part. The
three-peaked Mount Cerberus was constructed within the caldera during the
Holocene. Each of the peaks contains a summit crater; lava flows on the N
flank of Cerberus appear younger than those on the south side. Other
post-caldera volcanoes include the symmetrical Sugarloaf Peak SSE of the
caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake
in the NE part of the caldera. Most documented historical eruptions have
originated from Cerberus, although Coats (1950) considered that both
Sugarloaf and Lakeshore Cone within the caldera could have been active
during historical time.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://avo.alaska.edu/

Ongoing Activity

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

JMA reported that during 29 January-1 February incandescence from
Minamidake Crater (at Aira Calderaâ??s Sakurajima volcano) was often visible
nightly. Seven explosions generated eruption plumes that rose as high as 2
km above the crater rim and ejected bombs 1,000-1,300 km away from the
crater. The sulfur dioxide emission rate was 1,100 tons per day on 2
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/

Asamayama  | Honshu (Japan)  | 36.406Â°N, 138.523Â°E  | Summit elev. 2568 m

On 5 February JMA lowered the Alert Level for Asamayama to 1 (on a scale of
1-5) noting that no deformation or crater incandescence had been detected
since late November 2020, sulfur dioxide emissions had trended downward
beginning in December, volcanic earthquakes were recorded only occasionally
since mid-December, and the number of small-amplitude volcanic tremors were
recorded occasionally and had not increased.

Geologic Summary. Asamayama, Honshu's most active volcano, overlooks the
resort town of Karuizawa, 140 km NW of Tokyo. The volcano is located at the
junction of the Izu-Marianas and NE Japan volcanic arcs. The modern Maekake
cone forms the summit and is situated east of the horseshoe-shaped remnant
of an older andesitic volcano, Kurofuyama, which was destroyed by a
late-Pleistocene landslide about 20,000 years before present (BP). Growth
of a dacitic shield volcano was accompanied by pumiceous pyroclastic flows,
the largest of which occurred about 14,000-11,000 BP, and by growth of the
Ko-Asama-yama lava dome on the east flank. Maekake, capped by the Kamayama
pyroclastic cone that forms the present summit, is probably only a few
thousand years old and has an historical record dating back at least to the
11th century CE. Maekake has had several major plinian eruptions, the last
two of which occurred in 1108 (Asamayama's largest Holocene eruption) and
1783 CE.

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 3-4, 6-7, and 9 February ash plumes from
Dukono rose to 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted S, SW, and
NE. 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 2.3 km (7,500 ft) a.s.l. and drifted E. 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

Ibu  | Halmahera (Indonesia)  | 1.488Â°N, 127.63Â°E  | Summit elev. 1325 m

PVMBG reported that during 3-9 February gray-and-white ash plume from Ibu
rose 200-800 m above the summit and drifted in multiple directions. The
Alert Level remained at 2 (on a scale of 1-4), and the public was warned to
stay at least 2 km away from the active crater and 3.5 km away on the N
side.

Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along
the NW coast of Halmahera Island has large nested summit craters. The inner
crater, 1 km wide and 400 m deep, contained several small crater lakes
through much of historical time. The outer crater, 1.2 km wide, is breached
on the north side, creating a steep-walled valley. A large parasitic cone
is located ENE of the summit. A smaller one to the WSW has fed a lava flow
down the W flank. A group of maars is located below the N and W flanks.
Only a few eruptions have been recorded in historical time, the first a
small explosive eruption from the summit crater in 1911. An eruption
producing a lava dome that eventually covered much of the floor of the
inner summit crater began in December 1998.

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

Karymsky  | Eastern Kamchatka (Russia)  | 54.049Â°N, 159.443Â°E  | Summit
elev. 1513 m

KVERT reported that a thermal anomaly over Karymskyâ??s summit crater was
visible in satellite images on 2 February. Weather clouds obscured views on
the other days during 30 January-5 February. The Aviation Color Code
remained at Orange (the second highest level on a four-color scale).

Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern
volcanic zone, is a symmetrical stratovolcano constructed within a
5-km-wide caldera that formed during the early Holocene. The caldera cuts
the south side of the Pleistocene Dvor volcano and is located outside the
north margin of the large mid-Pleistocene Polovinka caldera, which contains
the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding
Karymsky eruptions originated beneath Akademia Nauk caldera, located
immediately south. The caldera enclosing Karymsky formed about 7600-7700
radiocarbon years ago; construction of the stratovolcano began about 2000
years later. The latest eruptive period began about 500 years ago,
following a 2300-year quiescence. Much of the cone is mantled by lava flows
less than 200 years old. Historical eruptions have been vulcanian or
vulcanian-strombolian with moderate explosive activity and occasional lava
flows from the summit crater.

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

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

HVO reported that lava from a vent on the inner NW wall of Kilaueaâ??s
Halema`uma`u Crater streamed down the cone into a perched lava lake during
3-9 February. The western half of the lake dropped from 213 m on 3 February
to 211 m on 4 February and stayed at that level during 5-6 February; the
drop in lake level was likely the result of summit deflation that was
detected by tiltmeters. The lake level had risen to 214 m by the morning of
7 February coincident with the onset of summit inflation. A small dome
fountain was visible at the entry point of lava into the lake on 8
February. The stagnant E half of the lake, separated by a series of surface
cracks, was about 5 m lowed than the W half.

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 Strombolian and sometimes Vulcanian activity at
Klyuchevskoy continued during 29 January-5 February and lava advanced down
the Apakhonchich drainage on the SE flank. A large bright thermal anomaly
was identified daily in satellite images. Steam-and-gas plumes with some
ash rose to 6 km (19,700 ft) a.s.l. and drifted 92 km in multiple
directions. The Aviation Color Code remined at Orange (the second highest
level on a four-color scale).

Geologic Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's
highest and most active volcano. Since its origin about 6000 years ago, the
beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced
frequent moderate-volume explosive and effusive eruptions without major
periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen
volcano and lies SE of the broad Ushkovsky massif. More than 100 flank
eruptions have occurred during the past roughly 3000 years, with most
lateral craters and cones occurring along radial fissures between the
unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m
elevation. The morphology of the 700-m-wide summit crater has been
frequently modified by historical eruptions, which have been recorded since
the late-17th century. Historical eruptions have originated primarily from
the summit crater, but have also included numerous major explosive and
effusive eruptions from flank craters.

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

Lewotolo  | Lomblen Island (Indonesia)  | 8.274Â°S, 123.508Â°E  | Summit
elev. 1431 m

PVMBG reported that the eruption at Lewotolo continued during 3-9 February.
Gray-and-white ash plumes rose 200-700 m above the summit and drifted E and
SE. During 5-9 February Strombolian explosions ejected material 100-350 m
above the summit and incandescent material was ejected 300-500 m SE from
the crater. Rumbling and occasional banging sounds were reported. 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

On 6 February INSIVUMEH reported increased Strombolian activity and a
higher number of explosions at Pacayaâ??s Mackenney Crater. The explosions
rattled nearby houses and ejected ballistics as far as 500 m from the
crater. Ash plumes rose as high as 650 m above the summit and drifted 5 km
W, NW, and N. Ashfall was reported in areas downwind including San
Francisco de Sales, El Cedro, Calderas, El Bejucal, and MesÃas Altas. Lava
effusion also increased and two active lava flows, 800 and 1,200 m long,
were advancing. On 8 February ash plumes rose almost 600 m and drifted 30
km NW and W, and 10 km N. Explosions ejected ballistics as far as 300 m
from the crater.

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/

Popocatepetl  | Mexico  | 19.023Â°N, 98.622Â°W  | Summit elev. 5393 m

CENAPRED reported that each day during 3-9 January there were 14-34 steam,
gas, and ash emissions from PopocatÃ©petl. Minor crater incandescence from
the crater was visible during a few of the nights. An explosion at 2138 on
6 February generated an eruption plume with low ash content that rose 2 km
above the summit and drifted NE. The Alert Level remained at Yellow, Phase
Two (middle level on a three-color scale).

Geologic Summary. VolcÃ¡n PopocatÃ©petl, whose name is the Aztec word for
smoking mountain, rises 70 km SE of Mexico City to form North America's
2nd-highest volcano. The glacier-clad stratovolcano contains a
steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is
modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier
volcano. At least three previous major cones were destroyed by
gravitational failure during the Pleistocene, producing massive
debris-avalanche deposits covering broad areas to the south. The modern
volcano was constructed south of the late-Pleistocene to Holocene El Fraile
cone. Three major Plinian eruptions, the most recent of which took place
about 800 CE, have occurred since the mid-Holocene, accompanied by
pyroclastic flows and voluminous lahars that swept basins below the
volcano. Frequent historical eruptions, first recorded in Aztec codices,
have occurred since Pre-Columbian time.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
https://www.gob.mx/cenapred

Sheveluch  | Central Kamchatka (Russia)  | 56.653Â°N, 161.36Â°E  | Summit
elev. 3283 m

KVERT reported that a thermal anomaly over Sheveluch was identified in
satellite images on 29 January as well as 2 and 4 February. Weather clouds
obscured views of the volcano on the other days during 30 January-5
February. The Aviation Color Code remained at Orange (the second highest
level on a four-color scale).

Geologic Summary. The high, isolated massif of Sheveluch volcano (also
spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya
volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most
active volcanic structures. The summit of roughly 65,000-year-old Stary
Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera
breached to the south. Many lava domes dot its outer flanks. The Molodoy
Shiveluch lava dome complex was constructed during the Holocene within the
large horseshoe-shaped caldera; Holocene lava dome extrusion also took
place on the flanks of Stary Shiveluch. At least 60 large eruptions have
occurred during the Holocene, making it the most vigorous andesitic volcano
of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions
have provided valuable time markers for dating volcanic events in
Kamchatka. Frequent collapses of dome complexes, most recently in 1964,
have produced debris avalanches whose deposits cover much of the floor of
the breached caldera.

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

Sinabung  | Indonesia  | 3.17Â°N, 98.392Â°E  | Summit elev. 2460 m

PVMBG reported that the eruption at Sinabung continued during 3-9 February,
though weather conditions sometimes prevented visual confirmation. Dense
white plumes rose as high as 1 km above the summit and drifted in multiple
directions. An eruptive event was recorded on 5 February but was not seen,
and on 6 February a pyroclastic flow traveled 2.5 km down the flank. The
Darwin VAAC noted that ash plumes rose to 3 km (10,000 ft) a.s.l. and
drifted W and NNW that same day. On 7 February ash plumes rose 1 km above
the summit and drifted E, SE, and S, causing ashfall in the Karo Regency.
The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion
zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE
sector.

Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene
stratovolcano with many lava flows on its flanks. The migration of summit
vents along a N-S line gives the summit crater complex an elongated form.
The youngest crater of this conical andesitic-to-dacitic edifice is at the
southern end of the four overlapping summit craters. The youngest deposit
is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at
740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric
activity was seen at the summit and upper flanks in 1912. No confirmed
historical eruptions were recorded prior to explosive eruptions during
August-September 2010 that produced ash plumes to 5 km above the summit.

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

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

Antara News
https://www.antaranews.com/berita/1986704/guguran-abu-gunung-sinabung-teramati-setinggi-1000-meter

Soufriere St. Vincent  | St. Vincent  | 13.33Â°N, 61.18Â°W  | Summit elev.
1220 m

University of the West Indies Seismic Research Centre (UWI-SRC) and
National Emergency Management Organisation (NEMO) reported that the lava
dome in SoufriÃ¨re St. Vincentâ??s main crater continued to grow during 1-9
February. Gas data analysis conducted during a field visit showed that
sulfur dioxide emissions were first detected on 1 February, suggesting that
ground water was drying up and no longer interacting with the gas species.
The dome had an estimated volume of 5.93 million cubic meters. Scientists
observed damaged vegetation, likely caused by fire, on the NW part of the
crater (just N of the dome). A report on 6 February stated that the dome
continued to spread laterally N and S, with N as the dominant growth
direction. Gas-and-steam continued to rise from the top of the dome as well
as along the contact of the old and new domes. Scientists visited the
Wallibou Hot Spring area on 7 February after a report of anomalously higher
temperatures and gas odors; they collected water samples and took
temperatures measurements for later analysis. Initial findings suggested
the presence of hydrogen sulfide in that area and temperatures that had
increased around 5-6 degrees; the lead scientist noted that based on their
findings there was no increased risk associated with the hot springs. NEMPO
reminded the public to avoid the volcano and that descending into the
crater remained extremely dangerous. The Alert Level remained at Orange
(the second highest level on a four-color scale).

Geologic Summary. SoufriÃ¨re St. Vincent is the northernmost and youngest
volcano on St. Vincent Island. The NE rim of the 1.6-km wide summit crater
is cut by a crater formed in 1812. The crater itself lies on the SW margin
of a larger 2.2-km-wide caldera, which is breached widely to the SW as a
result of slope failure. Frequent explosive eruptions after about 4,300
years ago produced pyroclastic deposits of the Yellow Tephra Formation,
which cover much of the island. The first historical eruption took place in
1718; it and the 1812 eruption produced major explosions. Much of the
northern end of the island was devastated by a major eruption in 1902 that
coincided with the catastrophic Mont PelÃ©e eruption on Martinique. A lava
dome was emplaced in the summit crater in 1971 during a strictly effusive
eruption, forming an island within a lake that filled the crater. A series
of explosive eruptions in 1979 destroyed the 1971 dome and ejected the
lake; a new dome was then built.

Sources: University of the West Indies Seismic Research Centre (UWI-SRC)
http://www.uwiseismic.com/;

National Emergency Management Organisation (NEMO), Government of Saint
Vincent and the Grenadines http://nemo.gov.lc/

Suwanosejima  | Ryukyu Islands (Japan)  | 29.638Â°N, 129.714Â°E  | Summit
elev. 796 m

JMA reported that incandescence at Suwanosejimaâ??s Ontake Crater was
occasionally visible at night during 29 January-5 February. Intermittent
explosions produced ash plumes that rose as high as 1.2 km above the crater
rim and ejected bombs 300 m away from the crater. The Alert Level remained
at 2 (on a 5-level scale).

Geologic 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 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.

Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/

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End of Volcano Digest - 8 Feb 2021 to 10 Feb 2021 (#2021-13)
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