Smithsonian / USGS Weekly Volcanic Activity Report 24 February-2 March 2021

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Wed, 3 Mar 2021 13:21:30 -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

24 February-2 March 2021

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

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

New Activity/Unrest: Etna, Sicily (Italy)  | Klyuchevskoy, Central
Kamchatka (Russia)  | Krysuvik, Iceland  | Kuchinoerabujima, Ryukyu Islands
(Japan)  | Pacaya, Guatemala  | Sinabung, Indonesia

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 continuing episodes of lava fountaining at Etnaâ??s Southeast
Crater (SEC) and 24 and 28 February. Strombolian activity at two vents in
SEC increased during the late afternoon of 24 February. Lava overflowed the
crater at 1820 and headed ESE towards the Valle de Bove. During 1900-2122
lava fountains rose as high as 500 m above the summit. A second lava flow
traveled SW, and at 2100 a pyroclastic flow descended 1 km into the Valle
de Bove. An eruption plume rose as high as 11 km a.s.l.

Weak Strombolian activity was visible at 0810 on 28 February. Lava
fountaining began at 0839, feeding lava flows that traveled E, and abruptly
intensified at 0902 with jets of lava rising 700 m above the crater rim. An
eruption plume rose as high as 11 km a.s.l. and drifted ESE, causing
ashfall in areas downwind. A small lava overflow at the S part of SEC began
at 0909, followed by a pyroclastic flow at 0920. Lava fountaining ended at
0933, though the lava flow descending E remained active.

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/

Klyuchevskoy  | Central Kamchatka (Russia)  | 56.056Â°N, 160.642Â°E  | Summit
elev. 4754 m

KVERT reported that the eruption at two vents on Klyuchevskoyâ??s lower NW
flank continued during 24-26 February. Both vents produced lava flows and
ejected lava 50 m high. A cinder cone had formed over the higher vent. A
bright thermal anomaly over the vents was identified in satellite images.
The Aviation Color Code remained 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.

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

Krysuvik  | Iceland  | 63.883Â°N, 22.083Â°W  | Summit elev. 360 m

IMO reported that seismicity in the area between KrÃ½suvÃk and
Reykjanes-Svartsengi volcanic systems remained elevated during 26
February-1 March. More than 6,000 earthquakes had been detected after a M
5.7 event was recorded at 1005 on 24 February; two of those events were
above M 5. The earthquakes were distributed over a 25-km-long section of a
N-S striking fault along the E-W striking plate boundary, primarily located
between Keilir and Fagradalsfjall. GPS data showed 4 cm of horizontal
displacement near the epicenter of the M 5.7 event. An InSAR interferogram
showed left-lateral movement over a large section of the plate boundary.
Tremor began to be recorded by several stations at 1425 on 3 March, in an
area located 2 km SW of Keilir. The signals possibly indicated magma rising
towards the surface and prompted IMO to raise the Aviation Color Code for
KrÃ½suvÃk to Orange.

Geologic Summary. The KrysuvÃk volcanic system (also spelled Krisuvik)
consists of a group of NE-SW-trending basaltic crater rows and small shield
volcanoes cutting the central Reykjanes Peninsula west of Kleifarvatn lake.
Several eruptions have taken place since the settlement of Iceland,
including the eruption of a large lava flow from the Ogmundargigar crater
row around the 12th century. The latest eruption took place during the 14th
century.

Source: Icelandic Meteorological Office (IMO) http://en.vedur.is/

Kuchinoerabujima  | Ryukyu Islands (Japan)  | 30.443Â°N, 130.217Â°E  | Summit
elev. 657 m

JMA reported that the number of volcanic earthquakes located at shallow
depths beneath Kuchinoerabujimaâ??s Shindake Crater increased on 21 February
and remained elevated. The Alert Level was raised to 3 (the middle level on
a scale of 1-5) on 28 February. No other monitoring data showed upward
trends and no surficial changes were visible; sulfur dioxide emissions
remained low at 60 tons per day on 24 February.

Geologic Summary. A group of young stratovolcanoes forms the eastern end of
the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu
Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones
were erupted from south to north, respectively, forming a composite cone
with multiple craters. All historical eruptions have occurred from
Shindake, although a lava flow from the S flank of Furudake that reached
the coast has a very fresh morphology. Frequent explosive eruptions have
taken place from Shindake since 1840; the largest of these was in December
1933. Several villages on the 4 x 12 km island are located within a few
kilometers of the active crater and have suffered damage from eruptions.

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

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

INSIVUMEH and CONRED reported that during 23-25 February explosions at
Pacayaâ??s Mackenney Crater ejected incandescent material as high as 200 m. A
lava flow, originating from a vent 300 m below the summit crater, was about
1.1 km long and produced incandescent blocks from the flow front that
descended 300 m. more intense pulses of activity at the summit produced
dense ash plumes that drifted more than 30 km S and SW. Ashfall was noted
in areas downwind including Los Pocitos, Pacaya, El Rodeo, and El
Patrocinio. Explosions continued during 26-29 February, although weather
conditions sometime prevented visual confirmation.

RSAM data values notably increased during the morning of 1 March,
reflecting an increase in Strombolian activity. Moderate-to-strong
explosions ejected ballistics as high as 500 m above the summit. Ash plumes
rose 1 km above the summit and drifted W and SW, causing ashfall at least
in El Patrocinio. Incandescent material was ejected 150 m high, and ash
plumes drifted W; ashfall was reported in El Patrocinio. The lava flow on
the SSW flank was about 700 m long. On 2 March gas and ash plumes rose 150
m and drifted 2 km S. A lava flow on the SSW flank was 150 m long.

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.

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

Coordinadora Nacional para la ReducciÃ³n de Desastres (CONRED)
http://conred.gob.gt/

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

PVMBG reported that the eruption at Sinabung continued during 24 February-2
March. White plumes rose as high as 500 m above the summit most days. On 25
February avalanches of material traveled 500-1,000 m down the E, SE, and S
flanks. The Darwin VAAC noted that an ash plume rose to 4 km (13,000 ft)
a.s.l., or 1.5 km above the summit, and drifted SE, based on satellite
images and information from PVMBG. On 28 February avalanches of material
traveled 1,000-1,250 m down the E, SE, and S flanks; the VAAC noted that
ash plumes were visible in satellite images and rose to 3.4 km (11,000 ft)
a.s.l. (about 1 km above the summit) and drifted SW. On 1 March avalanches
of material descended the E, SE, and S flanks as far as 1.3 km.

A series of lava-dome collapses began at 0642 on 2 March. A total of 13
pyroclastic flows, each lasting between about two and eight minutes,
traveled 2-5 km SE and E. Ash plumes rose 4-5 km along the length of the
pyroclastic flows and drifted W, SW, S, and E. The VAAC reported that ash
plumes were visible in satellite images beginning at 0640 rising to 4.3 km
(14,000 ft) a.s.l. and drifting SW. Ash plumes rose to 7.6 km (25,000 ft)
a.s.l. and drifted W by 0758; within another 25 minutes the plumes had
risen to 12.2 km (40,000 ft) a.s.l. According to BNPB ashfall was noted in
17 villages in the Tiganderket District, eight villages in the Kutabuluh
District, and 15 villages in the Tigabinaga District. 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;

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

Ongoing Activity

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

JMA reported that during 22 February-1 March incandescence from Minamidake
Crater (at Aira Calderaâ??s Sakurajima volcano) was visible nightly. Three
explosions and four non-explosive events generated eruption plumes that
rose as high as 2.6 km above the crater rim and ejected bombs 0.6-1.3 km
away from the crater. 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

PVMBG reported that during 23-28 February ash plumes from Dukono rose
100-500 m above the summit and drifted SE and E. Weather conditions
prevented visual observations during 1-2 March. 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.

Source: 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 19-26 February that sent ash plumes to
3.6 km (11,800 ft) a.s.l. and drifted E and SE. Ashfall was reported in
Severo-Kurilsk on 20 February and a thermal anomaly was identified in
satellite images that same day. 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 5-15 explosions were recorded per hour during 23
February-2 March at Fuego, generating ash plumes as high as 1.1 km above
the crater rim. Shock waves rattled buildings around the volcano. Block
avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), TaniluyÃ¡
(SW), Las Lajas (SE), and Honda drainages, often reaching vegetated areas.
Ashfall was reported on most days in several areas downwind including
Morelia (9 km SW), PanimachÃ© I (8 km SW), Santa SofÃa (12 km SW), El
Porvenir (8 km ENE), and San Pedro Yepocapa (8 km NW). Incandescent
material was ejected 100-400 m above the summit almost daily. Curtains of
old ash deposits remobilized by strong winds were observed during 26-27
February.

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.

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

Coordinadora Nacional para la ReducciÃ³n de Desastres (CONRED)
http://conred.gob.gt/

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

PVMBG reported that during 24 February-2 March gray-and-white ash plumes
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/

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 24 February-2 March. The
depth of the western part of the lake deepened from 217 to 219 m. Lava
effused from a submerged vent and rapidly developed a thin crust as it
flowed E towards the main stagnant island. The crust occasionally
overturned at â??plateâ?? boundaries, and lava rarely overflowed onto the
sloped margins of the lake. The E half of the lake remained solidified; the
crusted area expanded towards the W. The sulfur dioxide emission rate was
700-1,100 tons/day during 25-26 February and 1 March.

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/

Kirishimayama  | Kyushu (Japan)  | 31.934Â°N, 130.862Â°E  | Summit elev. 1700
m

JMA lowered the Alert Level for Kirishimayama to 1 (on a scale of 1-5) on 1
March. The number of volcanic earthquakes had increased in late December
2020 but then began to decline in January 2021 and continued the downward
trend through February. No other observation data showed signs of unrest.

Geologic Summary. Kirishimayama is a large group of more than 20 Quaternary
volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene
dominantly andesitic group consists of stratovolcanoes, pyroclastic cones,
maars, and underlying shield volcanoes located over an area of 20 x 30 km.
The larger stratovolcanoes are scattered throughout the field, with the
centrally located Karakunidake being the highest. Onamiike and Miike, the
two largest maars, are located SW of Karakunidake and at its far eastern
end, respectively. Holocene eruptions have been concentrated along an E-W
line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent
small-to-moderate explosive eruptions have been recorded since the 8th
century.

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

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

PVMBG reported that the eruption at Lewotolok continued during 24
February-2 March; weather conditions sometimes hindered visual
observations. Gray-and-white ash plumes rose 100-700 m above the summit and
drifted N, E, SE, and W. 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 Lewotolok (or Lewotolo) 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/

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

BPPTKG reported that the 2021 lava dome just below Merapiâ??s SW rim and the
new lava dome in the summit crater both continued to grow during 19-25
February. The 2021 lava-dome volume was an estimated 618,700 cubic meters
on 25 February, with a growth rate of about 13,600 cubic meters per day. A
total of three pyroclastic flows traveled 1.9 km down the SW flank. One of
the three, recorded at 1652 on 25 February, was followed by minor ashfall
in Kali Tengah Lor, Kali Tengah Kidul, Deles, and Tlukan. 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.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi
(BPPTKG) http://www.merapi.bgl.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 200-1,200 m above Raungâ??s
summit during 24 February-2 March. Ash plumes were sometimes dense and
drifted mainly N, 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/

Sangay  | Ecuador  | 2.005Â°S, 78.341Â°W  | Summit elev. 5286 m

IG reported a high level of activity at Sangay during 24 February-2 March.
Seismicity was characterized by 3-254 daily explosions, long-period
earthquakes, and signals indicating emissions. Weather clouds often
prevented visual observations of the volcano, but the Washington VAAC
recorded almost daily ash plumes that rose as high as 1.5 km above the
summit and drifted mainly NW, W, and SW. A seismic station possibly
recorded a lahar on 25 February.

Geologic Summary. The isolated Sangay volcano, located east of the Andean
crest, is the southernmost of Ecuador's volcanoes and its most active. The
steep-sided, glacier-covered, dominantly andesitic volcano grew within
horseshoe-shaped calderas of two previous edifices, which were destroyed by
collapse to the east, producing large debris avalanches that reached the
Amazonian lowlands. The modern edifice dates back to at least 14,000 years
ago. It towers above the tropical jungle on the east side; on the other
sides flat plains of ash have been sculpted by heavy rains into
steep-walled canyons up to 600 m deep. The earliest report of a historical
eruption was in 1628. More or less continuous eruptions were reported from
1728 until 1916, and again from 1934 to the present. The almost constant
activity has caused frequent changes to the morphology of the summit crater
complex.

Source: Instituto GeofÃsico-Escuela PolitÃ©cnica Nacional (IG)
http://www.igepn.edu.ec/

Santa Maria  | Guatemala  | 14.757Â°N, 91.552Â°W  | Summit elev. 3745 m

INSIVUMEH reported that during 23 February-2 March explosions at Santa
MarÃa's Santiaguito lava-dome complex generated ash plumes that rose as
high as 1 km above the complex. Collapses of blocky lava from the Caliente
dome sent avalanches mainly down the SW flank, often reaching the base of
the complex. Minor pyroclastic flows were occasionally generated. Ash
plumes drifted W and SW, often causing minor ashfall around the volcano.

Geologic Summary. Symmetrical, forest-covered Santa MarÃa volcano is part
of a chain of large stratovolcanoes that rise above the Pacific coastal
plain of Guatemala. The sharp-topped, conical profile is cut on the SW
flank by a 1.5-km-wide crater. The oval-shaped crater extends from just
below the summit to the lower flank, and was formed during a catastrophic
eruption in 1902. The renowned Plinian eruption of 1902 that devastated
much of SW Guatemala followed a long repose period after construction of
the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito
lava-dome complex has been growing at the base of the 1902 crater since
1922. Compound dome growth at Santiaguito has occurred episodically from
four vents, with activity progressing W towards the most recent, Caliente.
Dome growth has been accompanied by almost continuous minor explosions,
with periodic lava extrusion, larger explosions, pyroclastic flows, and
lahars.

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

Semeru  | Eastern Java (Indonesia)  | 8.108Â°S, 112.922Â°E  | Summit elev.
3657 m

The Darwin VAAC reported that during 24-25 February ash plumes from Semeru
rose to 4-4.3 km (13,000-14,000 ft) a.s.l. and drifted SE based on
satellite images. PVMBG noted that weather conditions prevented visual
observations during 24 February-2 March. The Alert Level remained at 2 (on
a scale of 1-4), with a general exclusion zone of 1 km and extensions to 4
km in the SSE sector.

Geologic Summary. Semeru, the highest volcano on Java, and one of its most
active, lies at the southern end of a volcanic massif extending north to
the Tengger caldera. The steep-sided volcano, also referred to as Mahameru
(Great Mountain), rises above coastal plains to the south. Gunung Semeru
was constructed south of the overlapping Ajek-ajek and Jambangan calderas.
A line of lake-filled maars was constructed along a N-S trend cutting
through the summit, and cinder cones and lava domes occupy the eastern and
NE flanks. Summit topography is complicated by the shifting of craters from
NW to SE. Frequent 19th and 20th century eruptions were dominated by
small-to-moderate explosions from the summit crater, with occasional lava
flows and larger explosive eruptions accompanied by pyroclastic flows that
have reached the lower flanks of the volcano.

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

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 during 19-26 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

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 24
February-2 March. The rate of growth was variable, though overall slow. Gas
emissions continued to damage vegetation in the summit area as well as on
the SW flank. The monitoring teams replaced a camera and continue to
improve the seismic and GPS networks. 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 intermittent eruptive events at Suwanosejimaâ??s Ontake Crater
during 19-26 February. These events produced ash plumes that rose as high
as 1.8 km above the crater rim and ejected bombs 200 m away from the
crater. Ashfall was reported in Toshima village (4 km SSW). 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 - 2 Mar 2021 to 3 Mar 2021 (#2021-23)
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