Smithsonian / USGS Weekly Volcanic Activity Report 7-13 April 2021

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Wed, 14 Apr 2021 13:10:00 -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

7-13 April 2021

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

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

Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Ibu, Halmahera (Indonesia)  | Kilauea,
Hawaiian Islands (USA)  | Lewotolok, Lembata Island (Indonesia)  | Merapi,
Central Java (Indonesia)  | Raung, Eastern Java (Indonesia)  | Semeru,
Eastern Java (Indonesia)  | Sheveluch, Central Kamchatka (Russia)  |
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

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

KVERT reported that the explosive eruption that began at Karymsky on 3
April continued through 11 April. A thermal anomaly was visible in
satellite images during 2-6 April; weather conditions obscured views on
other days. The 3 April explosion generated an ash plume that rose to 8.5
km (27,900 ft) a.s.l. and drifted 255 km NE. At 1745 on 11 April explosions
produced ash plumes that rose to 4 km (13,100 ft) a.s.l. and drifted at
least 65 km SE. The Aviation Color Code was raised to Orange (the second
highest level on a four-color scale) on 3 April.

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

Krysuvik-Trolladyngja  | Iceland  | 63.917Â°N, 22.067Â°W  | Summit elev. 360 m

IMO reported that the fissure eruption in the W part of the
KrÃ½suvÃk-TrÃ¶lladyngja volcanic system, close to Fagradalsfjall on the
Reykjanes Peninsula, continued during 7-13 April. Lava from the third
fissure flowed S into Geldingadalur and NE towards the Meradalir valley
site. Flows from the three fissures connected into one flow field on 7
April. Another new fissure opened at around 0300 on 10 April, halfway
between two existing fissures, and all four fissures were simultaneously
active. Lava flowed towards Geldingadalur. Gas-rich emission plumes were
visible in webcam images rising 1.1-1.3 km (3,600-4,300 ft) a.s.l. At least
two new vents opened on 13 April based on webcam views. On 14 April IMO
noted that lava was flowing from at least eight vents and unverified
reports form the morning suggested two additional vents had opened. Sulfur
dioxide gas flux was 29 kilograms per second, comparable to measurements
collected during the previous few weeks.

IMO warned visitors that new fissures could open without adequate visible
warning, especially in an area just S of Keilir, by Litla-HrÃºt, where
seismicity was concentrated. They also warned of increased gas emissions
hazards. The Aviation Color Code remained Orange due to the lack of ash and
tephra emissions.

Geologic Summary. The KrÃ½suvÃk-TrÃ¶lladyngja volcanic system is described by
the Catalogue of Icelandic Volcanoes as an approximately 50-km-long
composite fissure swarm trending about N38Â°E, including a 30-km-long swarm
of fissures, with no central volcano. It is one of the volcanic systems
arranged en-echelon along the Reykjanes Peninsula west of Kleifarvatn lake.
The Fagradalsfjall and KrÃ½suvÃk fissure swarms are considered splits or
secondary swarms of the KrÃ½suvÃkâ??TrÃ¶lladyngja volcanic system. Small shield
volcanoes have produced a large portion of the erupted volume within the
system. Several eruptions have taken place since the settlement of Iceland,
including the eruption of a large basaltic lava flow from the Ogmundargigar
crater row around the 12th century. The latest eruption, identified through
tephrochronology, 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 reported that the eruption at Pacayaâ??s Mackenney Crater continued
during 7-13 April. Explosions during 6-7 April produced ash plumes that
rose 1 km above the summit and drifted 10 km W and SW. Ballistics were
ejected 50-150 m above the summit. Explosions during 8-9 and 11-12 April
produced ash plumes that rose as high as 1 km and drifted as far as 10 km
NE, W, and SW.

The lava flow on the W and SW flanks was 3.7 km long and continued to be
fed. Incandescent lava blocks were spalled from the flow front and
vegetation was set on fire. The lava advanced W onto the La BreÃ±a farm and
SW towards El Patrocinio and El Rodeo, near the Campo Alegre farm. On 12
April the flows burned La BreÃ±a coffee and avocado plantations. By 13 April
the lava flows were 3.8 km long, and within 370 m of houses in El
Patrocinio. Another flow front was 250 m E of El Rodeo, and obstructed the
road that connects El Rodeo, El Caracol, and Los Pocitos.

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/

Piton de la Fournaise  | Reunion Island (France)  | 21.244Â°S, 55.708Â°E  |
Summit elev. 2632 m

OVPF reported that a seismic crisis at Piton de la Fournaise began at 1457
on 9 April and was accompanied by rapid deformation beneath the S flank.
Seismicity indicated that a fissure opened at 1900 but could not be
visually confirmed due to weather conditions. The Alert Level was raised to
2-2. During an overflight at 0840 on 10 April scientists observed a
NNW-oriented fissure, 700 m S of ChÃ¢teau Fort. Activity was focused at two
vents, each producing lava fountains that were no higher than 30 m tall,
though fountains also rose from other parts of the fissure. Slow-moving
â??aâ??a lava flowed SE and then curved E and advanced 1.6 km to 1,800
elevation. The N end of the fissure was no longer active. Two cones had
formed over the main vents and were growing larger; by 11 April the more
northern vent was the larger of the two. Fountains rose 30-60 m and the
lava flow had advanced to 1,750 m elevation. By 1900 on 11 April the lava
flow was 3.2 km long and had reached 1,690 m elevation. Lava fountaining
continued at the two vents during 12-13 April, rising 20-60 m. The lava
flow continued to advance; by 13 April the flow was about 3.6 km long and
had reached 1,500-1,550 m elevation.

Geologic Summary. The massive Piton de la Fournaise basaltic shield volcano
on the French island of RÃ©union in the western Indian Ocean is one of the
world's most active volcanoes. Much of its more than 530,000-year history
overlapped with eruptions of the deeply dissected Piton des Neiges shield
volcano to the NW. Three calderas formed at about 250,000, 65,000, and less
than 5000 years ago by progressive eastward slumping of the volcano.
Numerous pyroclastic cones dot the floor of the calderas and their outer
flanks. Most historical eruptions have originated from the summit and
flanks of Dolomieu, a 400-m-high lava shield that has grown within the
youngest caldera, which is 8 km wide and breached to below sea level on the
eastern side. More than 150 eruptions, most of which have produced fluid
basaltic lava flows, have occurred since the 17th century. Only six
eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from
fissures on the outer flanks of the caldera. The Piton de la Fournaise
Volcano Observatory, one of several operated by the Institut de Physique du
Globe de Paris, monitors this very active volcano.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)
http://www.ipgp.fr/

Semisopochnoi  | Aleutian Islands (USA)  | 51.93Â°N, 179.58Â°E  | Summit
elev. 1221 m

AVO reported that low-level ash emissions from Semisopochnoi were visible
in satellite images on 12 April along with a steam plume drifting E beyond
the island. Additionally, new ash deposits extending SE at least to the
coastline were also visible. The event was recorded by the regional
infrasound network. The Aviation Color Code and the Volcano Alert Level
remained at Orange and Watch, respectively.

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 eruptions have originated
from Cerberus, although Coats (1950) considered that both Sugarloaf and
Lakeshore Cone could have been recently active.

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

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
effusive eruption at SoufriÃ¨re St. Vincent (often simply referred to as â??La
Soufriereâ??) became explosive on 9 April after a period of increased
seismicity, gas emission, and rapid dome growth. Earthquake swarms were
recorded during 22-25 March and 5 April, signifying a change in the
eruption pattern. Small earthquakes associated with dome growth were
recorded on 7 April. Episodes of tremor indicating movement of magma and
fluids close to the surface began at 0300 on 8 April and were again
recorded at 0530, 0800, 1015, and 1300, slowly increasing in magnitude.
Five long-period earthquakes and two brief swarms of VT events occurred in
between the tremor episodes; ash venting occurred with the last episode.
Sulfur dioxide emissions were identified in satellite data, and clouds of
steam and gas were visible from the Belmont Observatory. Later that
evening, incandescent material over the vent area was visible in webcam
images, and views from the observatory indicated that the dome had grown
significantly. The Alert Level was raised to Red at around 1830, and the
Prime Minister issued an evacuation order for the Red Zone at the N part of
the island, affecting 16,000-20,000 people.

An explosive eruption began at 0840 on 9 April when an ash plume rose to 8
km (27,900 ft) a.s.l. and drifted mainly ENE. Ash fell across the island,
affecting communities including Chateaubelair and Petite Bordel, the
observatory, Belmont and surrounding areas at the S end of the island, and
forcing the closure of the Argyle International Airport (20 km S). NEMO
stated that evacuations in the Orange and Red zones were impeded by
significant ashfall and poor visibility, but by the evening most residents
had been evacuated. A second period of vigorous ash venting began at 1445
and initially rose about 4 km (13,100 ft) a.s.l. Lightning was visible in
the rising plume. Successive explosions and ash pulses fed the plume for
hours and it rose to 16 km (52,000 ft) a.s.l. A third explosive series
began at 1835. Ash venting occurred through the night, causing ashfall
across St. Vincent and reaching Barbados, about 165 km E, significantly
impacting residents on that island.

Periods of banded tremor began at 0330 on 10 April, lasting for periods of
20-30 minutes with 1-3-hour gaps. The tremor episodes were associated with
explosive activity and stronger pulses of ash emissions to higher
altitudes; ash plumes rose to 10.6-16 km (35,000-52,000 ft) a.s.l.
throughout the day. The Washington VAAC stated that ash plumes during 9-10
April had drifted as far as 1,200 km ESE and about 3,000 km ENE. The
Grantley Adams International Airport (GAIA) in Barbados also closed.

Ashfall continued to be widespread on 10 April; deposit thickness varied
from less than 1 mm in Colonaire (~12.5 km SSE) to 10-15 mm in Rabacca
(~7.4 km SSE). Scientists reported darkness at the observatory at 1617;
video showed intense and continuous ashfall. Satellite data confirmed that
explosions had excavated the 2020-2021 lava dome and parts of the 1979
dome, leaving a large crater.

Overnight during 10-11 April ash again fell island-wide, and also in the
Grenadines (to the SSW), Barbados, and Saint Lucia (50 km NNE). Explosions
early on 11 April were followed by widespread power and water outages on
the island as reported by NEMO, and some houses had collapsed under the
significant ashfall. Beginning around midday the periods between episodes
of high-amplitude tremor lengthened from 1.5-4 hours to 5-8 hours. The VAAC
reported that through the day ash plumes rose 12.2-16 km (40,000-52,000 ft)
a.s.l. and continued to drift long distances to the ENE, E, and SE. A large
explosion at 0415 on 12 April produced an ash plume that rose to 12.8 km
(42,000 ft) a.s.l. Pyroclastic flows descended several valleys on the S and
W flanks, reaching the coast at Morne Ronde (4.3 km W), Larikai (3.5 km
WNW), and Trois Loupes Bay (3.5 km NW). Damage to vegetation was extensive
along the W coast, stretching from Larikai Bay to Turner Bay. The pattern
of seismicity again changed; high-amplitude tremor episodes ceased, but two
low-amplitude and one high-amplitude episode were recorded during
0600-1700. Explosivity or notable ash venting coincided with the episodes;
the spacing between explosive events increased.

A series of Vulcanian explosions began at 0630 on 13 April and lasted about
30 minutes. The VAAC stated that a dense ash plume rose to 11 km (35,000
ft) a.s.l. and drifted E and SE, as well as N and NE. Pyroclastic flows
traveled about 6 km WSW, reached the ocean at Wallibou Bay, and extended
past the coastline over the sea. Scientists observed the western coastline
later in the day and noted that pyroclastic flows had descended all valleys
from Larikai (W) to Wallibou, a stretch about 5 km long. Lahar deposits
were observed in the Sandy Bay area. The VAAC noted that at 1850 a new ash
emission rose to 7.6 km (25,000 ft) a.s.l. and was associated with a
thermal anomaly. UWI-SRC stated that a large explosion was recorded around
2300. Pyroclastic flows overnight were channeled to the E into the Rabacca
River drainage. The Montserrat Volcano Observatory stated that a sulfur
odor and minor ashfall from SoufriÃ¨re St. Vincent was observed on their
island (390 km NNW).

Daily satellite-based measurements of SO2 were notable beginning on 9
April. Though the initial explosion at 0840 showed relatively minor SO2
emissions, stronger, continuous ash and SO2 emissions began later on 9
April (at 1445) and continued into the next day, transitioning into
discrete explosive events that continued a least through 14 April.
Satellite data showed about 0.4 teragrams (Tg) of SO2 in the plume on 10
April, with some stratospheric injection. Simon Carn noted that this makes
the La Soufriere eruption the largest tropical SO2 emission since the 2011
Nabro eruption, and the largest in the Caribbean since satellite
measurements began in 1979. The SO2 plume initially fanned out to the NE,
E, and SE across the Atlantic Ocean. Measurements during 11-13 April showed
similar results of 0.4-0.6 Tg SO2 depending on altitude. The eastern edge
of the gas plume reached about 4,700 km to the W coast of Africa by 12
April, and another 2,000 km inland to Mali and Niger on 13 April.

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/;

Simon Carn http://www.volcarno.com/;

Reuters
https://www.reuters.com/article/us-caribbean-volcano/power-outages-hit-saint-vincent-island-amid-volcano-tremors-idUSKBN2BY0N0
;

UN News Centre https://news.un.org/en/story/2021/04/1089592;

Montserrat Volcano Observatory (MVO) http://www.mvo.ms/;

ReliefWeb
https://reliefweb.int/report/saint-vincent-and-grenadines/st-vincent-grenadines-volcano-9-april-2021-0
;

Capella Space https://www.capellaspace.com/;

Nation News https://www.nationnews.com/2021/04/13/airport-closed-friday/;

Caribbean Handbook on Risk Information Management
http://www.charim.net/stvincent/maps

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

JMA reported that incandescence from Suwanosejima's Ontake Crater was
visible at night during 5-9 April. Four explosions generated ash plumes
that rose as high as 1.6 km above the crater rim and ejected bombs 600 m
away. Ashfall was reported in Toshima village (4 km SSW) during 8-9 April.
The Alert Level remained at 2 and the public was warned to stay 1 km away
from the crater.

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/

Ongoing Activity

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

JMA reported that at 0641 on 5 April and explosion at Minamidake Crater (at
Aira Calderaâ??s Sakurajima volcano) produced an ash plume that rose as high
as 3 km above the crater rim and ejected material 800-1,000 m away from the
crater. Five explosions were recorded during 9-12 April. The highest ash
plume rose 2.1 km and bombs were ejected as far as 900 m from the crater.
Crater incandescence was visible nightly. 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 6-10 April ash plumes from Dukono rose 100-700 m
above the summit and drifted E, SE, and S. Weather conditions prevented
visual observations during 11-12 April. 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 2-9 April that sent ash plumes to 4.5 km
(14,800 ft) a.s.l. and drifted in multiple directions. The Aviation Color
Code remained at Orange (the second highest level on a four-color scale).

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

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

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

PVMBG reported that during 6-13 April gray-and-white ash plumes from Ibu
rose 200-1,000 m above the summit 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 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, has contained several small crater lakes.
The 1.2-km-wide outer crater is breached on the N, creating a steep-walled
valley. A large cone grew ENE of the summit, and 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. The first observed and recorded eruption was a small
explosion from the summit crater in 1911. Eruptive activity began again in
December 1998, producing a lava dome that eventually covered much of the
floor of the inner summit crater along with ongoing explosive ash emissions.

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 the W vent on the inner NW wall of Kilauea's Halema`uma`u
Crater continued to supply the lava lake during 31 March-6 April. Lava
flowed at a low rate from the main vent into the lake through crusted-over
channels and submerged inlets. The total depth of the lake measured about
226 m and lava continued to circulate in the W part; the E half of the lake
remained solidified and expanded toward the W. The sulfur dioxide emission
rate was 1,200 tons/day on 1 April. HVO field crews observed weak
spattering from two areas at the W vent during 1-2 April. 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 Strombolian eruption at Lewotolok continued during
6-13 April. Gray-and-white ash plumes rose as high as 750 m above the
summit and drifted in multiple directions. Incandescent material was
ejected 300-500 m above the summit on most days and 500 m SE on 8 April.
Incandescent material was ejected to the E during 9 and 11-12 April.
Rumbling was occasionally audible. The Alert Level remained at 3 (on a
scale of 1-4) and the public was warned to stay 4 km away from the summit
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 lava dome just below Merapiâ??s SW rim and the lava
dome in the summit crater both continued to grow during 1-8 April. The SW
rim lava-dome volume was an estimated 1,098,000 cubic meters on 7 April,
with a growth rate of about 12,800 cubic meters per day, and continued to
shed material down the flank. A total of 13 pyroclastic flows traveled a
maximum of 1.5 km down the SW flank. Incandescent avalanches, recorded 119
times, traveled as far as 1.1 km down the SW flank. The summit lava dome
had grown to 75 m tall. Minor ashfall was reported in Ngipiksari (8 km
SSW), Klangon (4 km S), and Deles (3 km SE) on 3 April. The Alert Level
remained at 3 (on a scale of 1-4), and the public was 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-and-white ash plumes rose 50-600 m above
Raung's summit during 6-13 April 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/

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

PVMBG reported that the eruption at Semeru continued during 7-13 April,
though weather conditions often prevented visual confirmation.
Gray-and-white ash plumes rose as high as 500 m during 9 and 11-12 April.
The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion
zone of 1 km and extensions to 5 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: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) http://vsi.esdm.go.id/

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 2-9 April. 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 6-13 April.
Weather conditions sometimes prevented visual observations of the volcano,
though white fumarolic plumes were visible almost daily rising as high as
700 m above the summit and drifting in multiple directions. An eruptive
event on 7 April produced a gray ash plume that rose 1 km. Two eruptive
events the next day generated ash plumes that rose as high as 700 m.
Avalanches traveled as far as 1.5 km E and SE during 8-11 April. Ash plumes
rose 500-1,000 m high on 10 April. 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.

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

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

==============================================================

Volcano Listserv is a collaborative venture among Arizona State University
(ASU), Portland State University (PSU), the Global Volcanism Program (GVP)
of the Smithsonian Institution's National Museum of Natural History, and
the International Association for Volcanology and Chemistry of the Earth's
Interior (IAVCEI).

ASU - http://www.asu.edu/

PSU - http://pdx.edu/

GVP - http://www.volcano.si.edu/

IAVCEI - https://www.iavceivolcano.org/

To unsubscribe from the volcano list, send the message:

signoff volcano

to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxx.

To contribute to the volcano list, send your message to:

volcano@xxxxxxx.  Please do not send attachments.

==============================================================

------------------------------

End of Volcano Digest - 12 Apr 2021 to 14 Apr 2021 (#2021-39)
*************************************************************