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

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Thu, 11 Mar 2021 08:55:16 -0700

3-3-3-3-3-3-3-3-3-3-3-3-3

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

Smithsonian / USGS Weekly Volcanic Activity Report

3-9 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  | Pacaya, Guatemala  | Pinatubo,
Luzon (Philippines)  | Sinabung, Indonesia  | Taal, Luzon (Philippines)  |
Veniaminof, 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 continuing episodes of lava fountaining at Etnaâ??s Southeast
Crater (SEC) on 2, 4, and 7 March. Weak Strombolian activity began at SEC
at 1145 on 2 March, then intensified at 1234 and produced an ash plume.
Lava fountaining began at 1324. Ash plumes rose to 9 km above the summit
and drifted S, causing lapilli to fall in Nicolosi (16 km S), Aci San
Antonio (18 km SE), Pedara (15 km SSE), and Catania (29 km SSE). Lava
fountaining ceased at 1550, ending the eighth episode.

The ninth episode began at the SEC as weak Strombolian at 0120 on 4 March.
Ash emissions were visible at 0200 but dispersed quickly. Strombolian
activity at Voragine (VOR) was also visible with ejected material rising
above the crater rim. Lava fountaining began at SEC at 0320, but by 0515
the activity had decreased. Lava flows that advanced towards the Valle de
Bove were fed by spattering and a new vent that opened at the E base of the
SEC. Strombolian activity at VOR changed to 300-m-tall lava fountaining at
0850. Ash plumes rose 11 km above the summit and caused lapilli to fall in
Fiumefreddo (19 km ENE), Linguaglossa (17 km NE), and the area of Reggio
Calabria.

The tenth episode began with Strombolian explosions at SEC and minor lava
effusion at the new vent at the E base of SEC during the first hour on 7
March. Strombolian activity intensified at 0430; an eruption plume rose 5
km above the summit and drifted E. Lava overflowed the SEC onto the E flank
and expanded into the Valle de Bove, reaching an elevation of 2,800 m by
0450. Strombolian activity again intensified beginning at 0520 and the lava
flow advanced to 2,700 m elevation. Lava fountaining started at 0720 and
ended at 0810. An eruption plume rose 10 km and drifted E. Ash and lapilli
fell in Milo (11 km ESE), Fornazzo (10 km ESE), Trepunti (17 km ESE),
Giarre (17 km ESE), Macchia di Giarre (16 km ESE), Mascali (18 km E),
Riposto (19 km ESE), and Torre Archirafi (20 km ESE). Strombolian activity
resumed at 1050 and was over by 1500.

Strombolian activity at SEC returned at 1914 on 9 March. Lava overflowed
the crater at 2013 and advanced towards the Valle de Bove. Strombolian
activity increased at 2100 and ash emissions drifted NE. The lava flow
reached 2,900 m elevation.

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 from vents on Klyuchevskoyâ??s lower NW
flank continued during 26 February-5 March. A large, bright thermal anomaly
over the vents was identified daily in satellite images. IVS FEB RAS
volcanologists visited the field site on 2 March during good weather
conditions. They estimated that the cinder cone was 54 m high and 101 m
wide at the base. Lava effused from the cone and traveled downslope,
melting ice and snow that formed muddy streams. 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 the KrÃ½suvÃk and
Reykjanes-Svartsengi volcanic systems remained elevated during 4-10 March.
GPS and InSAR data indicated that the intrusion was ongoing, with magma
moving slowly SW along a fault between Keilir and Fagradalsfjall at depths
of 2-6 km. Seismicity fluctuated during 6-7 March but continued to be
elevated; the largest event was a M 5.1 on 7 March. The geophysical and
satellite data on 8 March suggested that magma movement had decelerated
over the past week, and was possibly as shallow as 1 km. A burst of
seismicity was recorded around 0520 on 9 March, concentrated at the S end
of the intrusion in an area that was most likely source of the magma. On 10
March IMO stated that more than 34,000 earthquakes had been detected during
the past two weeks, a total larger than all of 2020 which was characterized
as an unusually high year for seismicity. The Aviation Color Code for
KrÃ½suvÃk remained at 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/

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

INSIVUMEH and CONRED reported that during 2-6 March strong Strombolian
explosions at Pacayaâ??s Mackenney Crater produced ash plumes that rose as
high as 1 km above the summit and drifted W, SW, and S. Tephra fell in
areas downwind including El Patrocinio (5 km W), El Rodeo (4 km WSW), San
Francisco de Sales (5 km N), El Cedro (9 km NNW), Calderas (3 km N), and
Las Jazmines (5 km W), and in the municipalities of PalÃn (10 km WNW) and
Escuintla (22 km SW). Periods of lava fountaining were visible, and
incandescent material was ejected 300-1,000 m high. Three lava flows were
active and all had several branches; one traveled SSW, one traveled S, and
one on the SE flank was 800-1,200 m long. During 6-8 March strong
explosions ejected material as high as 500 m and produced dense ash plumes
that rose up to 1 km. Lava flows continued to be active, sometimes
producing block avalanches from the ends. On 8 March the S-flank flow was
about 850 m long and continued to generated block avalanches. Strong
explosions during 8-9 March ejected ballistics 300-500 m away from the
crater. Dense ash plumes rose up to 1.5 km and drifted 30 km SW and S. The
lava flow on the S flank was 900 m long and shed blocks from the end.

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/

Pinatubo  | Luzon (Philippines)  | 15.13Â°N, 120.35Â°E  | Summit elev. 1486 m

PHIVOLCS raised the Alert Level for Pinatubo to 1 (on a scale of 0-5) on 4
March noting elevated seismicity with a total of 1,722 earthquakes recorded
in two swarms since 20 January. The first swarm was recorded during 20-26
January and was comprised of local M 1-2.5 events that occurred along the
Sacobia Lineament fault at depths of 15-28 km. A more persistent swarm
followed; it was comprised of local M 0.5-2.8 events at depths of 10-35 km
along another fault system, with a few shallower earthquakes occurring at
both ends of the swarm. Carbon dioxide flux at Pinatubo Crater lake was 378
tonnes per day in February, within background ranges that topped 1,000
tonnes per day during the last decade. Minor temperature increases were
recorded at fumarolic vents.

Geologic Summary. Prior to 1991 Pinatubo volcano was a relatively unknown,
heavily forested lava dome complex located 100 km NW of Manila with no
records of historical eruptions. The 1991 eruption, one of the world's
largest of the 20th century, ejected massive amounts of tephra and produced
voluminous pyroclastic flows, forming a small, 2.5-km-wide summit caldera
whose floor is now covered by a lake. Caldera formation lowered the height
of the summit by more than 300 m. Although the eruption caused hundreds of
fatalities and major damage with severe social and economic impact,
successful monitoring efforts greatly reduced the number of fatalities.
Widespread lahars that redistributed products of the 1991 eruption have
continued to cause severe disruption. Previous major eruptive periods,
interrupted by lengthy quiescent periods, have produced pyroclastic flows
and lahars that were even more extensive than in 1991.

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

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

PVMBG reported that the eruption at Sinabung continued during 3-9 March.
According to the Darwin VAAC an ash plume was identified in satellite
images rising to 3 km (10,000 ft) a.s.l. (or 600 m above the summit) and
drifting NW on 5 March. The observatory noted that avalanches of material
traveled 500 m down the SE flank during 6-7 March, and an ash plume rose 1
km and drifted NW at 1910 on 7 March. 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

Taal  | Luzon (Philippines)  | 14.002Â°N, 120.993Â°E  | Summit elev. 311 m

PHIVOLCS raised the Alert Level for Taal to 2 (on a scale of 0-5) on 9
March based on increased activity recorded since 13 February. During 8-9
March the seismic network recorded a total of 28 volcanic tremor events,
four low-frequency volcanic earthquakes, and one hybrid event at depths of
less than 1.5 km. These events added to the totals of 866 volcanic tremor
events and 141 low-frequency volcanic earthquakes recorded during 13
February-9 March. Overall, seismicity over the past month indicated
increased magmatic and hydrothermal activity at shallow depths beneath Taal
Volcano Island (TVI).

Over the past month minor deformation centered at a source beneath the SE
part of TVI was evident in monitoring data, including integrated real-time
ground tilt and continuous GPS, daily Electronic Distance Measurement (EDM)
monitoring, and InSAR. The data also showed slow and steady inflation
across the Taal region after the 2020 eruption. Geochemical data collected
from Taalâ??s Main Crater lake indicated a continuous acidification of the
water from pH 2.79 to 1.59 between January 2020 and mid-February 2021.
Microgravity data was consistent with magma migration. PHIVOLCS strongly
recommended no entry onto the island, and access to the Main Crater and
Daang Kastila fissure (along the walking trail) was strictly prohibited.

Geologic Summary. Taal is one of the most active volcanoes in the
Philippines and has produced some of its most powerful historical
eruptions. Though not topographically prominent, its prehistorical
eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km
Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2
surface lies only 3 m above sea level. The maximum depth of the lake is 160
m, and several eruptive centers lie submerged beneath the lake. The
5-km-wide Volcano Island in north-central Lake Taal is the location of all
historical eruptions. The island is composed of coalescing small
stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in
area during historical time. Powerful pyroclastic flows and surges from
historical eruptions have caused many fatalities.

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

Veniaminof  | United States  | 56.17Â°N, 159.38Â°W  | Summit elev. 2507 m

AVO reported that elevated sulfur dioxide gas emissions at Veniaminof were
first detected on 1 March and elevated surface temperatures were identified
in satellite images sometime during 2-3 March. At 0513 on 4 March
infrasound sensors recorded a small explosion, prompting AVO to raise the
Volcano Alert Level to Watch and the Aviation Color Code to Orange. A
low-level ash plume, to less than 3 km (10,000 ft) a.s.l., was visible in
satellite and webcam images drifting SSE and minor ash deposits around the
volcano were visible. Small emissions continued at least through 1048 that
day. Sulfur dioxide emissions were visible in a webcam image on 5 March.
Numerous small explosions were recorded during 6-7 March; some of them were
heard and felt by residents in Perryville (35 km SE). Elevated surface
temperatures were identified in satellite images, suggesting lava near or
at the surface. During times of clear weather low-level gas-and-ash plumes
were visible in satellite and webcam data and observed by pilots. The
plumes mainly stayed below 3 km (10,000 ft) a.s.l., but at times went as
high as 4.6 km (15,000 ft) a.s.l., and drifted 150 km NE.

On 7 March satellite images revealed that the emissions originated from a
small cone in the summit caldera. Additionally, lava was likely effusing
under the intra-caldera glacier in an area on the flank about 1 km E of the
coneâ??s summit. This area produced incandescence and strongly elevated
surface temperatures, as well as a small steam plume and meltwater. During
8-9 March satellite images showed a small, steam-rich plume drifting about
10 km NE at 4.6 km (15,000 ft) a.s.l.

Geologic Summary. Veniaminof, on the Alaska Peninsula, is truncated by a
steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700
years ago. The caldera rim is up to 520 m high on the north, is deeply
notched on the west by Cone Glacier, and is covered by an ice sheet on the
south. Post-caldera vents are located along a NW-SE zone bisecting the
caldera that extends 55 km from near the Bering Sea coast, across the
caldera, and down the Pacific flank. Historical eruptions probably all
originated from the westernmost and most prominent of two intra-caldera
cones, which rises about 300 m above the surrounding icefield. The other
cone is larger, and has a summit crater or caldera that may reach 2.5 km in
diameter, but is more subdued and barely rises above the glacier surface.

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 1-8 March incandescence from Minamidake Crater (at
Aira Calderaâ??s Sakurajima volcano) was visible nightly. An explosion at
1810 on 1 March ejected bombs 600-900 m away from the crater; an eruption
plume was not confirmed. That same day the sulfur dioxide emission rate was
high, at 2,900 tons per day. An explosion on 5 March produced an eruption
plume that rose 2.7 km above the summit and ejected bombs 800-1,100 m away.
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, the Darwin VAAC reported that
during 7-9 March ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft)
a.s.l. and drifted E, SE, and SW. 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 26-28 February and 1-2 March that sent
ash plumes to 3.6 km (11,800 ft) a.s.l. and drifted in multiple directions.
Ashfall was reported in Severo-Kurilsk on 26 February and 2 March. 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

Kikai  | Japan  | 30.793Â°N, 130.305Â°E  | Summit elev. 704 m

In response to an eruption at Satsuma Iwo-jima, a subaerial part of Kikaiâ??s
NW caldera rim, on 2 November 2019 JMA had raised the Alert Level to 2 (on
a 5-level scale). Since then, surveillance cameras sometimes recorded minor
incandescence reflected in emitted plumes. On 8 March JMA revised the Alert
Level guidelines, keeping the level at 2, but reducing the exclusion zone
around the crater from 1 km to 500 m.

Geologic Summary. Kikai is a mostly submerged, 19-km-wide caldera near the
northern end of the Ryukyu Islands south of Kyushu. It was the source of
one of the world's largest Holocene eruptions about 6,300 years ago when
rhyolitic pyroclastic flows traveled across the sea for a total distance of
100 km to southern Kyushu, and ashfall reached the northern Japanese island
of Hokkaido. The eruption devastated southern and central Kyushu, which
remained uninhabited for several centuries. Post-caldera eruptions formed
Iodake lava dome and Inamuradake scoria cone, as well as submarine lava
domes. Historical eruptions have occurred at or near Satsuma-Iojima (also
known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW
caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small
island 2 km E of Tokara-Iojima, was formed during submarine eruptions in
1934 and 1935. Mild-to-moderate explosive eruptions have occurred during
the past few decades from Iodake, a rhyolitic lava dome at the eastern end
of Tokara-Iojima.

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

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 2-8 March through a
submerged inlet. The sulfur dioxide emission rate was 1,000 tons/day during
2-3 March, and 800 tons/day on 7 March. The depth of the western part of
the lake fluctuated around 219-220 m. The E half of the lake remained
solidified and lower that the W half, with the crusted E half expanding
towards the W. Rangefinder measurements and visual observations indicated
that the eastern and western portions of the lake were rising at the same
rate, suggesting that lava was accumulating under the crusted eastern
portion.

In recent weeks a part of the cone, several meters NE of the main vent,
occasionally fed short (less than 100 m) lava flows that entered the lake
at the crusted margins. During 5-7 March flows from this vent poured lava
into the lake at several shifting inlets, though lava also accumulated on
the lake margin within 50 m of the vent. By midday on 7 March the flows had
built a perched lava pond on the NW lake margin, but it abruptly collapsed
just after 1300. The Aviation Color Code remained at Orange and the Volcano
Alert Level remained at Watch.

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/

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

PVMBG reported that the eruption at Lewotolok continued during 3-9 March;
weather conditions sometimes hindered visual observations. Gray-and-white
ash plumes rose 100-1,000 m above the summit and drifted E, SE, SW, and W.
Incandescent material was ejected 300-800 m SE from the crater during 3-6
March. Rumbling and occasional thumping 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 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 2-9 March. Ash plumes drifted mainly 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 3-9 March. Seismicity
was characterized by daily explosions, long-period earthquakes, and signals
indicating emissions. Weather clouds often prevented visual observations of
the volcano, but satellite and webcam images recorded daily ash plumes.

Ash plumes were notable during 5-6 March and impacted communities downwind
with ashfall. According to the Washington VAAC ash plumes rose 5.8-12.2 km
(19,000-40,000 ft) a.s.l. and drifted 170-370 km SW, W, and NW; ash at
altitudes of 5.8-8.2 km (19,000-27,000 ft) a.s.l. drifted 185 km E. During
5-6 March ashfall was reported in Alfredo Baquerizo Moreno (132 km W), but
fell more significantly in AlausÃ (61 km WSW), Chunchi (73 km SW), CumandÃ¡
(90 km WSW), Guamote (42 km WNW), Pallatanga (70 km W), Milagro (140 km W),
San Jacinto de Yaguachi (150 km W), Samborondon (170 km W), Daule (180 km
W), and DurÃ¡n (168 km W). SNGRE reported that the ashfall affected a total
of 108,457 people (23,750 families) as well as numerous crops and animals;
they distributed volcano-related aid kits to impacted populations.

Ashfall continued to impact multiple communities during 6-7 March. Ash fell
in Guayaquil (175 km W), General Antonio Elizalde (97 km WSW), SimÃ³n
BolÃvar, Milagro (140 km W), San Jacinto de Yaguachi (150 km W), El Triunfo
(125 km WSW), Daule, SamborÃ³ndon (170 km W), Coronel MarceliÃ±o MaridueÃ±a
(120 km WSW), DurÃ¡n, Naranjito, Alfredo Baquerizo Moreno, Playas (240 km
WSW), Guamote (40 km WNW), AlausÃ (60 km SW), Pallatanga (70 km W), ChunchÃ
(72 km SW), and Colta (55 km NW).

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.

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

Servicio Nacional de GestiÃ³n de Riesgos y Emergencias (SNGRE)
https://www.gestionderiesgos.gob.ec/

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 26 February-5 March. 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 slowly grow during
2-8 March. The SE part of the dome was in line with the pre-existing
fumarolic area on the 1979 dome. Gas plumes continued to damage vegetation
in the summit area as well as on the SW flank. 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 26 February-2 March. Bombs were ejected as far as 600 m away from
the crater and ashfall was reported in Toshima village (4 km SSW). The
number of explosions began increasing on 2 March; the total recorded
through 1500 on 7 March was 139, but by 1500 on 8 March there was only one
additional explosion. The Tokyo VAAC reported that ash plumes rose 0.9-2.1
km (3,000-7,000 ft) a.s.l. during 3-7 March. An explosion at 0317 on 6
March ejected tephra as high as 500 m above the crater rim and bombs 900 m
away. 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.

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

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

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End of Volcano Digest - 8 Mar 2021 to 11 Mar 2021 (#2021-25)
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