Smithsonian / USGS Weekly Volcanic Activity Report 8-14 December 2021

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7-7-7-7-7-7-7-7-7-7-7-7-7-7


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


Smithsonian / USGS Weekly Volcanic Activity Report

8-14 December 2021



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

URL: https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPQhPeBH0$ 
<https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvF0I-VUxM$>





New Activity/Unrest: Awu, Sangihe Islands (Indonesia)  | Davidof, United
States  | Semeru, Eastern Java (Indonesia)



Ongoing Activity: Aira, Kyushu (Japan)  | Etna, Sicily (Italy)  | Great
Sitkin, Andreanof Islands (USA)  | Karymsky, Eastern Kamchatka (Russia)  |
Kilauea, Hawaiian Islands (USA)  | La Palma, Spain  | Lewotolok, Lembata
Island (Indonesia)  | Merapi, Central Java (Indonesia)  | Pavlof, United
States  | Semisopochnoi, Aleutian Islands (USA)  | Sheveluch, Central
Kamchatka (Russia)  | Suwanosejima, Ryukyu Islands (Japan)  |
Whakaari/White Island, North Island (New Zealand)





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





Awu  | Sangihe Islands (Indonesia)  | 3.689°N, 125.447°E  | Summit elev.
1318 m



PVMBG reported that volcanic seismicity at Awu had increased beginning in
October. Notably, the number of shallow volcanic earthquakes increased to
7-26 events per day from the previous maximum of 5 daily events. The number
of deep volcanic earthquakes also increased. The Alert Level was raised to
2 (on a scale of 1-4) and the public was warned to stay 1 km away from the
summit crater. The report also noted that no emissions nor any other
surficial activity had been visible during 1 September-10 December, though
weather sometimes hindered views.



Geologic Summary. The massive Gunung Awu stratovolcano occupies the
northern end of Great Sangihe Island, the largest of the Sangihe arc. Deep
valleys that form passageways for lahars dissect the flanks of the volcano,
which was constructed within a 4.5-km-wide caldera. Powerful explosive
eruptions in 1711, 1812, 1856, 1892, and 1966 produced devastating
pyroclastic flows and lahars that caused more than 8000 cumulative
fatalities. Awu contained a summit crater lake that was 1 km wide and 172 m
deep in 1922, but was largely ejected during the 1966 eruption.



Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPRWBW4vw$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFn_mKT3M$>





Davidof  | United States  | 51.97°N, 178.33°E  | Summit elev. 328 m



Earthquake swarms either related to tectonic processes or volcanic unrest
were recorded in the vicinity of Davidof during 8-10 December. The largest
earthquake was a M 4.2 recorded at 1045 on 10 December. AVO raised the
Aviation Color Code to Yellow and the Volcano Alert Level to Advisory due
to the possibility of escalating volcanic unrest. Small earthquakes
continued to be detected during 11-14 December, though at a lower rate and
amplitude. Cloudy or mostly cloudy satellite and webcams views showed no
volcanic activity.



Geologic Summary. A cluster of small islands between Segula and Little
Sitkin in the western Aleutians, the largest of which is Davidof, are
remnants of a stratovolcano that collapsed during the late Tertiary,
forming a 2.7-km-wide caldera. The islands include Khvostof, Pyramid, Lopy,
and Davidof; the latter three form the eastern rim of the mostly submarine
caldera, sometimes referred to as the "Aleutian Krakatau." The islands were
constructed above a roughly 100-m-deep submarine platform extending NW to
Segula Island; the floor of the caldera lies 80 m below sea level. The
islands are vegetated, but lava flows are recognizable, and Smith et al.
(1978) suggested a possible Holocene age.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP91XK0Hc$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFNVxS97U$>





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



PVMBG reported that lava avalanches from the end of the 700-m-long lava
flow on Semeruâ??s SE flank descended 500 m during 7-8 December. Lava
avalanches were detected by the seismic network almost daily during 9-14
December, though weather conditions prevented visual confirmation. During
9-11 December crater incandescence was visible and gray-white ash plumes
rose 300-1,000 m above the summit. White plumes rose as high as 1 km above
the summit during 12-14 December.



According to BNPB, the death toll from the 4 December collapse event rose
to 48 by 13 December, 12 people were still missing, 21 were seriously
injured, and 9,374 people were in 129 evacuation centers. 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.



Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPRWBW4vw$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFn_mKT3M$>
;

Badan Nacional Penanggulangan Bencana (BNPB) https://urldefense.com/v3/__http://www.bnpb.go.id/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP0FOxNqI$ 
<https://urldefense.com/v3/__http://www.bnpb.go.id/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFmkRr2As$>







Ongoing Activity





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



JMA reported that incandescence from Minamidake Crater (at Aira Calderaâ??s
Sakurajima volcano) was visible at night during 6-13 December. As many as
five eruptive events generated plumes that rose 1.2 km above the crater
rim. The Alert Level remained at 3 (on a 5-level scale), and residents were
warned to stay 2 km away from the crater.



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) https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP-h_9Fyw$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFMsrQHcI$>





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



INGV reported that during 6-12 December activity at Etna was characterized
by gas emissions from all summit craters and ash emissions from Southeast
Crater (SEC); weather conditions prevented views during most of the week.
During 6-7 December Strombolian activity at SEC produced almost continuous
ash emissions that dispersed ENE. On 8 December the ash emissions were
diffuse and discontinuous, and dissipated near the summit. At 1805 on 13
December a new vent opened at the base of the W wall of the Valle del Bove,
at 2,180 m elevation. A lava flow emerged from the vents and descended a
few hundred meters.



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)
https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPffHnmys$ 
<https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvF9IedhJY$>





Great Sitkin  | Andreanof Islands (USA)  | 52.076°N, 176.13°W  | Summit
elev. 1740 m



AVO reported that slow lava effusion at Great Sitkin continued during 8-14
December and very low seismicity persisted. Elevated surface temperatures
at the summit, that were sometimes intense, were detected overnight during
10-11 and 13-14 December. A radar image acquired during 12-13 December
showed a growing flow field. The Aviation Color Code and the Volcano Alert
Level remained at Orange and Watch, respectively.



Geologic Summary. The Great Sitkin volcano forms much of the northern side
of Great Sitkin Island. A younger parasitic volcano capped by a small, 0.8
x 1.2 km ice-filled summit caldera was constructed within a large
late-Pleistocene or early Holocene scarp formed by massive edifice failure
that truncated an ancestral volcano and produced a submarine debris
avalanche. Deposits from this and an older debris avalanche from a source
to the south cover a broad area of the ocean floor north of the volcano.
The summit lies along the eastern rim of the younger collapse scarp.
Deposits from an earlier caldera-forming eruption of unknown age cover the
flanks of the island to a depth up to 6 m. The small younger caldera was
partially filled by lava domes emplaced in 1945 and 1974, and five small
older flank lava domes, two of which lie on the coastline, were constructed
along northwest- and NNW-trending lines. Hot springs, mud pots, and
fumaroles occur near the head of Big Fox Creek, south of the volcano.
Historical eruptions have been recorded since the late-19th century.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP91XK0Hc$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFNVxS97U$>





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



KVERT reported that during 2-3 December explosions at Karymsky generated
ash plumes that rose as high as 4.5 km (14,800 ft) a.s.l. and drifted 235
km ENE. A thermal anomaly was visible in satellite images during 2-4, 7,
and 9 December. Dates are based on UTC times. The Aviation Color Code
remained at Orange (the second highest level on a four-color scale).



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



Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPTCKwGbs$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvF7teF0DE$>





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



HVO reported that lava effusion continued at a vent in the lower W wall of
Kilaueaâ??s Halema`uma`u Crater on most days during 8-14 December. The vent
contained ponded and sometimes spattering lava that fed the lake through
the E part of the W wall cone. The size of the active part of the lake
varied, and lava periodically oozed from the cooler, outer margins of the
lake onto the lowest of the exposed down-dropped caldera floor blocks. The
sulfur dioxide emission rate was about 3,500 tonnes per day on 9 December.
The eruption paused on 11 December then resumed at 2100 on 13 December. The
Aviation Color Code and the Volcano Alert Level remained at Orange and
Watch, respectively.



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://urldefense.com/v3/__https://volcanoes.usgs.gov/observatories/hvo/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPd_FgOdM$ 
<https://urldefense.com/v3/__https://volcanoes.usgs.gov/observatories/hvo/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFxtiRSmg$>





La Palma  | Spain  | 28.57°N, 17.83°W  | Summit elev. 2426 m



The eruption at La Palma continued during 8-13 December, characterized by
sporadic Strombolian activity, occasional lava jetting, advancing and
sometimes branching lava flows, and daily ash-and-gas emissions. Seismicity
was low at depths of 10-15 km and very low at depths of 30-40 km. Volcanic
tremor levels were also generally low, though they fluctuated near the end
of the week concurrent with explosive activity.



During 8-12 December activity at several vents in the central and SE part
of the main cone was low, with only sporadic pulses of Strombolian activity
and ash emissions. Ash-and-gas plumes rose as high as 3.7 km a.s.l. and
drifted SSE, SSW, SW, and W. Very intense gas emissions were recorded
during 9-11 December. Small landslides from fractured areas in the upper
part of the secondary cone (on the E flank) descended the interior part of
the crater as well as the flanks. Lava from the vents moved through tubes
towards the western part of the flow field, though two main breakout flows
traveled W over older flows. The most active area was along the S margin of
flow 9, where 9 and 11 had joined, as lava continued to descend the sea
cliff and widen in the area of Las Hoyas. During 11-12 December lobes from
the S margins of the flow traveled S over new ground in the Las Norias area.



On 12 December several strong pulses of tremor were accompanied by intense
Strombolian activity, with the most intense events at 1200 and 1730 and
decreased activity during 1300-1700. A small overflow of lava from one of
the vents traveled N over older flows. One of the more intense periods
produced dense dark ash plumes that rose 6 km a.s.l. and ejected bombs
(some several meters in diameter) as far as 500 m away from the vent. New
collapses were visible in the main cone, enlarging the crater, and at the
secondary cone. During 12-13 December lava continued to travel W through
tubes in the central part of the flow field. At the S margins lava filled
in uncovered areas between flows 9 and 11. On 13 December tremor levels
fluctuated with pulses of intense signals. A period of major explosive
activity during 1745-1900 ejected bombs towards the N flank and produced
ash-and-gas plumes. At 1820 video showed lava jetting above the vent and
incandescent material falling onto the flanks. Activity at the vents
quieted afterwards; tremor decreased at 2000 and by 2200 had reached
background levels. Gas emissions from the vents were at high levels through
14 December. Lava continued to advance from the W base of the main cone on
14 December, though at a much lower rate compared to the day before. Small
breakouts were visible near Montaña Cogote and Las Norias.



Gas and ash emissions continued to impact island residents. Daily
measurements indicated that sulfur dioxide emissions persisted at â??highâ??
levels (between 1,000 and 29,999 tons per day). Suspended ash and high
concentrations of volcanic gases, specifically sulfur dioxide, triggered
periodic air-quality alerts mostly affecting the W part of the island
including Los Llanos de Aridane, El Paso, and Tazacorte; authorities warned
residents of affected areas to stay indoors. Residents and essential
personnel were often barred from entering the exclusion zones to irrigate
crops, gather belongings, and remove ash from streets and buildings,
especially in Las Manchas, Las Norias, and La Bombilla. During 12-13
December diffuse carbon dioxide emissions were 6.9-7.2 times average
background levels, specifically impacting the La Bombilla area where dead
birds were observed.



Geologic Summary. The 47-km-long wedge-shaped island of La Palma, the
NW-most of the Canary Islands, is composed of two large volcanic centers.
The older northern one is cut by the massive steep-walled Caldera
Taburiente, one of several massive collapse scarps produced by edifice
failure to the SW. The younger Cumbre Vieja, the southern volcano, is one
of the most active in the Canaries. The elongated volcano dates back to
about 125,000 years ago and is oriented N-S. Eruptions during the past
7,000 years have formed abundant cinder cones and craters along the axis of
Cumbre Vieja, producing fissure-fed lava flows that descend steeply to the
sea. Eruptions recorded since the 15th century have produced mild explosive
activity and lava flows that damaged populated areas. The southern tip of
the island is mantled by a broad lava field emplaced during the 1677-1678
eruption. Lava flows also reached the sea in 1585, 1646, 1712, 1949, and
1971.



Sources: Instituto Volcanológico de Canarias (INVOLCAN)
https://urldefense.com/v3/__http://www.involcan.org/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPqSXyr8A$ 
<https://urldefense.com/v3/__http://www.involcan.org/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFeGvyWuU$>
;

Instituto Geográfico Nacional (IGN) https://urldefense.com/v3/__https://www.ign.es/web/ign/portal__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPYb98mxw$ 
<https://urldefense.com/v3/__https://www.ign.es/web/ign/portal__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvF_c4WeVU$>
;

Gobierno de Canaries https://urldefense.com/v3/__http://www.gobcan.es/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPKleNlgo$ 
<https://urldefense.com/v3/__http://www.gobcan.es/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFtZl_qww$>





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



PVMBG reported that the eruption at Lewotolok continued during 8-14
December. Daily white-and-gray ash plumes that were sometimes dense rose as
high as 700 m above the summit, though weather conditions prevented visual
confirmation during 11-12 December. Incandescent material was ejected from
the vent up to 300 m during 7-11 December, and was accompanied by faint
rumbling. The Alert Level remained at 3 (on a scale of 1-4) and the public
was warned to stay 3 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) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPRWBW4vw$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFn_mKT3M$>





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



BPPTKG reported that Merapiâ??s lava domes, located just below the SW rim and
in the summit crater, had both grown during 3-9 December. The estimated
dome volumes were almost 1.63 million cubic meters for the SW dome and just
over 3 million cubic meters for the summit dome. The intensity of the
seismic signals remained at high levels. As many as 190 lava avalanches
traveled a maximum of 2 km SW down the Bebeng drainage. Four pyroclastic
flows traveled a maximum of 2.2 km SW. The Alert Level remained at 3 (on a
scale of 1-4), and the public was warned to stay 3-5 km away from the
summit based on location.



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) https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPXcev1Pc$ 
<https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFYjTZP70$>





Pavlof  | United States  | 55.417°N, 161.894°W  | Summit elev. 2493 m



AVO reported seismicity at Pavlof was elevated during 8-14 December, and
weak explosive activity was detected by geophysical sensors during 8-11 and
13-14 December. No ash emissions were visible, though satellite and webcam
views were often cloudy. Elevated surface temperatures were visible in
satellite images during 11-14 December; a lava flow on the E flank was
visible in images during 12-13 December. The Volcano Alert Level remained
at Watch and the Aviation Color Code remained at Orange.



Geologic Summary. The most active volcano of the Aleutian arc, Pavlof is a
2519-m-high Holocene stratovolcano that was constructed along a line of
vents extending NE from the Emmons Lake caldera. Pavlof and its twin
volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of
symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and
Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW
flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof
Sister, Pavlof has been frequently active in historical time, typically
producing Strombolian to Vulcanian explosive eruptions from the summit
vents and occasional lava flows. The active vents lie near the summit on
the north and east sides. The largest historical eruption took place in
1911, at the end of a 5-year-long eruptive episode, when a fissure opened
on the N flank, ejecting large blocks and issuing lava flows.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP91XK0Hc$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFNVxS97U$>





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



AVO reported that low-level eruptive activity and elevated seismicity at
Semisopochnoi's North Cerberus crater continued during 8-14 December.
Several daily explosions were detected in seismic and infrasound data.
Small ash clouds drifting at least 185 km SE were identified in satellite
images during 8-9 December. Persistent steam emissions occasionally
punctuated by ash emissions were visible in webcam views during 10-11
December, and ash emissions were visible the next day even though
conditions were mostly cloudy. The Aviation Color Code remained at Orange
and the Volcano Alert Level remained at Watch.



Geologic Summary. Semisopochnoi, the largest subaerial volcano of the
western Aleutians, is 20 km wide at sea level and contains an 8-km-wide
caldera. It formed as a result of collapse of a low-angle, dominantly
basaltic volcano following the eruption of a large volume of dacitic
pumice. The high point of the island is Anvil Peak, a double-peaked
late-Pleistocene cone that forms much of the island's northern part. The
three-peaked Mount Cerberus was constructed within the caldera during the
Holocene. Each of the peaks contains a summit crater; lava flows on the N
flank of Cerberus appear younger than those on the south side. Other
post-caldera volcanoes include the symmetrical Sugarloaf Peak SSE of the
caldera and Lakeshore Cone, a small cinder cone at the edge of Fenner Lake
in the NE part of the caldera. Most documented 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://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP91XK0Hc$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFNVxS97U$>





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



KVERT reported that a thermal anomaly over Sheveluch was identified in
satellite images during 3-10 December. 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)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPTCKwGbs$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvF7teF0DE$>





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



JMA reported that crater incandescence at Suwanosejima's Ontake Crater was
visible nightly during 6-13 December. No explosions were detected by the
seismic network, though eruption plumes rose 1-3.4 km and material was
ejected 400-700 m away from the crater. Ashfall was reported in Toshima
village (4 km SSW). The Alert Level remained at 3 and the public was warned
to stay 2 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) https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sP-h_9Fyw$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFMsrQHcI$>





Whakaari/White Island  | North Island (New Zealand)  | 37.52°S, 177.18°E  |
Summit elev. 294 m



GeoNet reported results from a 10 December overflight of Whakaari/White
Island, noting a significant increase of temperatures at the active vent
area. Temperatures in the main vent area were as high as 516 degrees
Celsius, an increase from the range of 202-264 degrees Celsius measured in
both September and November; temperatures over 500 degrees Celsius were
last recorded during July-August. Very minor ash emissions continued to be
visible with deposits only extending around the active vents. Gas emissions
had possibly decreased, though measurements had not been taken since 18
November. The water in the lake has receded likely due to recent weather
conditions. The Volcanic Alert Level remained at 2 and the Aviation Color
Code remained at Yellow.



Geologic Summary. The uninhabited Whakaari/White Island is the 2 x 2.4 km
emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty
about 50 km offshore of North Island. The island consists of two
overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater
is open at sea level, with the recent activity centered about 1 km from the
shore close to the rear crater wall. Volckner Rocks, sea stacks that are
remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826
have included intermittent moderate phreatic, phreatomagmatic, and
Strombolian eruptions; activity there also forms a prominent part of Maori
legends. The formation of many new vents during the 19th and 20th centuries
caused rapid changes in crater floor topography. Collapse of the crater
wall in 1914 produced a debris avalanche that buried buildings and workers
at a sulfur-mining project. Explosive activity in December 2019 took place
while tourists were present, resulting in many fatalities. The official
government name Whakaari/White Island is a combination of the full Maori
name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island
(referencing the constant steam plume) given by Captain James Cook in 1769.



Source: GeoNet https://urldefense.com/v3/__http://www.geonet.org.nz/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPPUboHF4$ 
<https://urldefense.com/v3/__http://www.geonet.org.nz/__;!!IKRxdwAv5BmarQ!JhlNWkQHzjxkC-GwNvsXcTq5hS52wGdUNZNn1z5aed_tKxXm5AV-iyvFbYNsD4c$>




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



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

PSU - https://urldefense.com/v3/__http://pdx.edu/__;!!IKRxdwAv5BmarQ!LLNB7-n_bnH7dnLs26QJ32RIDwYJEnO4A9QRt8mkXeW-Kyk8KmO1R0sPnzeKAPo$ 

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End of Volcano Digest - 13 Dec 2021 to 16 Dec 2021 (#2021-122)
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