Smithsonian / USGS Weekly Volcanic Activity Report 23-29 December 2020

Rachel Holsteen-Bruyere <rbruyere@xxxxxxx> · Wed, 30 Dec 2020 12:56:01 -0700

1-1-1-1-1-1-1-1-1-1-1-1-1-1

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

Smithsonian / USGS Weekly Volcanic Activity Report

23-29 December 2020

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)  | Karymsky, Eastern Kamchatka (Russia)
| Klyuchevskoy, Central Kamchatka (Russia)  | Merapi, Central Java
(Indonesia)  | Sheveluch, Central Kamchatka (Russia)  | Sinabung,
Indonesia  | Villarrica, Chile  | 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

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

HVO reported that the eruption from N and W fissure vents on the inner
walls of Kilaueaâ??s Halema`uma`u Crater continued to feed a growing lava
lake during 23-29 December. Lava erupted from the N and W vents during
23-26 December with lava fountains that were sometimes 10 m high. The lake
level rose above the N vent by 0300 on 26 December; later that day,
volcanologists noted that the lake was slowly draining at that location.
The W vent continued to feed the lake during 27-29 December. An island of
cooler, solidified lava (250 m by 135 m in dimension on 28 December) slowly
floated around on the lava lakeâ??s surface. The islandâ??s surface was about 6
m above the surface of the lava lake and was covered in tephra, possibly
remnants of explosive activity generated when lava first reached the water
lake.

The depth of the lava lake increased from 155 m to 169 m during 23-24
December. It continued to rise and was 176 m deep by 1400 on 25 December,
though a new, narrow, black rim along the N edge suggested that the lake
had briefly been 1-2 m deeper, and then drained back. The lake remained
176-177 m deep through 28 December, but by 29 December had deepened to 180
m. The lake volume was an estimated 22 million cubic meters, and was 770 by
490 m in dimension by 29 December.

Sulfur dioxide emissions decreased over the week, from around 30,000-40,000
tonnes/day on 23 December, to 20,000 tonnes/day on 25 December, 5,000-5,500
tonnes/day during 26-27, and finally dropping to 3,000 tonnes/day during
28-29 December. The emission plume carried Peleâ??s Hair and Peleâ??s Tears SW,
depositing the tephra in areas downwind, including on HVO monitoring
equipment and solar panels.

Geologic Summary. Kilauea, which overlaps the E flank of the massive Mauna
Loa shield volcano, has been Hawaii's most active volcano during historical
time. Eruptions are prominent in Polynesian legends; written documentation
extending back to only 1820 records frequent summit and flank lava flow
eruptions that were interspersed with periods of long-term lava lake
activity that lasted until 1924 at Halemaumau crater, within the summit
caldera. The 3 x 5 km caldera was formed in several stages about 1500 years
ago and during the 18th century; eruptions have also originated from the
lengthy East and SW rift zones, which extend to the sea on both sides of
the volcano. About 90% of the surface of the basaltic shield volcano is
formed of lava flows less than about 1100 years old; 70% of the volcano's
surface is younger than 600 years. A long-term eruption from the East rift
zone that began in 1983 has produced lava flows covering more than 100 km2,
destroying nearly 200 houses and adding new coastline to the island.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
https://volcanoes.usgs.gov/observatories/hvo/

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

JMA reported that the number of volcanic earthquakes at Shinmoedake
(Shinmoe peak, a stratovolcano of the Kirishimayama volcano group) began to
increase on 18 December and remained elevated. A total of 300 earthquakes
were located beneath the summit crater during 16-25 December. No changes
were detected in deformation and emission data. The Alert Level was raised
to 2 (on a scale of 1-5) on 25 December, and the public was warned to
exercise caution within a 2-km radius of the crater.

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

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

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

PVMBG reported that the eruption at Lewotolo continued during 23-29
December. Gray-and-white ash plumes were visible daily, rising as high as 1
km above the summit. Strombolian explosions were visible most nights
ejecting material 100-300 m above the summit crater. Rumbling and banging
noises were reported. Incandescent material was ejected as far as 1 km from
the crater to the E and SE during 24-25 and 27-29 December. The Alert Level
remained at 3 (on a scale of 1-4) and the public was warned to stay 4 km
away from the summer crater.

Geologic Summary. The Lewotolo (or Lewotolok) stratovolcano occupies the
eastern end of an elongated peninsula extending north into the Flores Sea,
connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is
symmetrical when viewed from the north and east. A small cone with a
130-m-wide crater constructed at the SE side of a larger crater forms the
volcano's high point. Many lava flows have reached the coastline. Eruptions
recorded since 1660 have consisted of explosive activity from the summit
crater.

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

Ruapehu  | North Island (New Zealand)  | 39.28Â°S, 175.57Â°E  | Summit elev.
2797 m

On 28 December GeoNet reported that during the previous week the
temperature of Ruapehuâ??s crater lake water slightly decreased from 43 to 41
degrees Celsius. Moderate-to-strong levels of volcanic tremor were recorded
along with a small number of shallow volcanic earthquakes. The largest
volcanic earthquake was an M 2.2 (on 26 December) which was uncommonly
large, and combined with elevated tremor indicated ongoing unrest. The
Volcanic Alert Level remained at 2 and the Aviation Color Code remained at
Yellow.

Geologic Summary. Ruapehu, one of New Zealand's most active volcanoes, is a
complex stratovolcano constructed during at least four cone-building
episodes dating back to about 200,000 years ago. The dominantly andesitic
110 km3 volcanic massif is elongated in a NNE-SSW direction and surrounded
by another 100 km3 ring plain of volcaniclastic debris, including the
Murimoto debris-avalanche deposit on the NW flank. A series of subplinian
eruptions took place between about 22,600 and 10,000 years ago, but
pyroclastic flows have been infrequent. A single historically active vent,
Crater Lake (Te Wai a-moe), is located in the broad summit region, but at
least five other vents on the summit and flank have been active during the
Holocene. Frequent mild-to-moderate explosive eruptions have occurred in
historical time from the Crater Lake vent, and tephra characteristics
suggest that the crater lake may have formed as early as 3,000 years ago.
Lahars produced by phreatic eruptions from the summit crater lake are a
hazard to a ski area on the upper flanks and to lower river valleys.

Source: GeoNet http://www.geonet.org.nz/

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

A new effusive eruption had built a lava dome in the summit crater of
SoufriÃ¨re St. Vincent when observed on 29 December by personnel from the
National Emergency Management Organisation (NEMO), St. Vincent and the
Grenadines, and the Alert Level was raised to Orange (the second highest
level on a four-color scale). The observers noted that the small
black-colored dome had grown on the WSW edge of the 1979 lava dome. The
University of the West Indies Seismic Research Centre (UWI-SRC) stated in a
press briefing that seismicity at the volcano began to increase in early
November and changes in the water lake and fumarolic area were noted on 16
December. A persistent thermal anomaly had been identified in satellite
data over the previous couple of days, which is what prompted the NEMO
field visit.

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 Somma crater, which is breached widely to the SW as
a result of slope failure. Frequent explosive eruptions since about 4300
years ago produced pyroclastic deposits of the Yellow Tephra Formation,
which blanket 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 in a lake that filled the crater prior to an
eruption in 1979. The lake was then largely ejected during a series of
explosive eruptions, and the dome was replaced with another.

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

National Emergency Management Organisation (NEMO) http://nemo.gov.lc/;

Searchlight
https://searchlight.vc/searchlight/breaking-news/2020/12/30/effusive-eruptions-taking-place-at-la-soufriere-residents-put-on-high-alert/

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

JMA reported that eruptive activity at Suwanosejimaâ??s Ontake Crater
increased on 21 December with more frequent explosions; a total of 423
explosions were recorded during 21-28 December. At 0248 on 28 December a
large eruptive event ejected large bombs 1.3 km SE of the crater and
produced a plume that rose 200 m above the crater rim and entered weather
clouds. The Alert Level was raised to 3 (on a 5-level scale).

Geologic Summary. The 8-km-long, spindle-shaped island of Suwanosejima in
the northern Ryukyu Islands consists of an andesitic stratovolcano with two
historically active summit craters. The summit is truncated by a large
breached crater extending to the sea on the east flank that was formed by
edifice collapse. Suwanosejima, one of Japan's most frequently active
volcanoes, was in a state of intermittent strombolian activity from Otake,
the NE summit crater, that began in 1949 and lasted until 1996, after which
periods of inactivity lengthened. The largest historical eruption took
place in 1813-14, when thick scoria deposits blanketed residential areas,
and the SW crater produced two lava flows that reached the western coast.
At the end of the eruption the summit of Otake collapsed forming a large
debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which
extends to the eastern coast. The island remained uninhabited for about 70
years after the 1813-1814 eruption. Lava flows reached the eastern coast of
the island in 1884. Only about 50 people live on the island.

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

Tengger Caldera  | Eastern Java (Indonesia)  | 7.942Â°S, 112.95Â°E  | Summit
elev. 2329 m

PVMBG reported that during 26-27 December white-and-gray plumes rose 50-700
m above the summit of Tengger Calderaâ??s Bromo cone. At 0550 on 28 December
a gas-and-ash emission rose at least 500 m above the summit according to an
observer. Ashfall was reported in the Ngadirejo area, about 5 km NE. The
Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to
stay outside of a 1-km radius of the crater.

Geologic Summary. The 16-km-wide Tengger caldera is located at the northern
end of a volcanic massif extending from Semeru volcano. The massive
volcanic complex dates back to about 820,000 years ago and consists of five
overlapping stratovolcanoes, each truncated by a caldera. Lava domes,
pyroclastic cones, and a maar occupy the flanks of the massif. The
Ngadisari caldera at the NE end of the complex formed about 150,000 years
ago and is now drained through the Sapikerep valley. The most recent of the
calderas is the 9 x 10 km wide Sandsea caldera at the SW end of the
complex, which formed incrementally during the late Pleistocene and early
Holocene. An overlapping cluster of post-caldera cones was constructed on
the floor of the Sandsea caldera within the past several thousand years.
The youngest of these is Bromo, one of Java's most active and most
frequently visited volcanoes.

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

Ongoing Activity

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

JMA reported that during 21-28 December incandescence from Minamidake
Crater (at Aira Calderaâ??s Sakurajima volcano) was often visible nightly.
The sulfur dioxide emission rate remained high, with 2,900 tons measured on
21 December. Six explosions were recorded, generating plumes that rose as
high as 2.4 km above the crater rim and ejected bombs 0.6-1.3 km away from
the crater. The Alert Level remained at 3 (on a 5-level scale).

Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay
contains the post-caldera Sakurajima volcano, one of Japan's most active.
Eruption of the voluminous Ito pyroclastic flow accompanied formation of
the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera
was formed during the early Holocene in the NE corner of the Aira caldera,
along with several post-caldera cones. The construction of Sakurajima began
about 13,000 years ago on the southern rim of Aira caldera and built an
island that was finally joined to the Osumi Peninsula during the major
explosive and effusive eruption of 1914. Activity at the Kitadake summit
cone ended about 4850 years ago, after which eruptions took place at
Minamidake. Frequent historical eruptions, recorded since the 8th century,
have deposited ash on Kagoshima, one of Kyushu's largest cities, located
across Kagoshima Bay only 8 km from the summit. The largest historical
eruption took place during 1471-76.

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

Dukono  | Halmahera (Indonesia)  | 1.693Â°N, 127.894Â°E  | Summit elev. 1229 m

PVMBG and the Darwin VAAC reported that on most days during 23-29 December
ash plumes from Dukono rose 100-600 m above the summit. Weather conditions
sometimes prevented visual observations. 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: 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

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 18-21 and 24 December; ash plumes rose up
to 5 km (16,400 ft) a.s.l. and drifted NE and SE. A thermal anomaly was
identified in satellite images during 18-19 December. 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

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

KVERT reported that a thermal anomaly over Karymsky was visible during
19-20 and 24 December. The Aviation Color Code remained at Orange (the
second highest level on a four-color scale).

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

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

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

KVERT reported that Strombolian and sometimes Vulcanian activity at
Klyuchevskoy continued during 18-25 December and lava advanced down the
Kozyrevsky drainage on the S flank. Lava first flowed down the S flank on 8
December. A large bright thermal anomaly was identified daily in satellite
images. Steam-and-gas plumes with some ash rose to 6 km (19,700 ft) a.s.l.
and drifted 340 km mainly E. The Kamchatka Volcanological Station field
team visited the area on 24 December to do work on field stations. They
observed explosions that ejected incandescent material 300 m above the
crater rim. A growing cinder cone in the summit crater was about 75 m
higher than part of the crater rim. The lava flow ended at about 3,700 m
elevation and spalled off incandescent material, descending an additional
350 m. The Aviation Color Code remined at Orange (the second highest level
on a four-color scale).

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

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

Kamchatka Volcanological Station http://volkstat.ru/

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

BPPTKG reported that during 12-17 December white emissions from Merapi rose
as high as 150 m above the summit. A comparison of photos taken on 11 and
15 December showed some slight morphological changes in the summit area;
drone footage from 14 December revealed no new lava dome material in the
summit crater. Rock avalanches traveled as far as 1.5 km down the Senowo
drainage on the NW flank on 14 December. Seismic activity was less intense
than the previous week. Electronic Distance Measurement (EDM) data
continued to measure a distance shortening between points in the NW at a
rate of 9 cm per day. The Alert Level remained at 3 (on a scale of 1-4).

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/

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 18-25 December. Two strong explosive events on 22
and 24 December generated large ash clouds that rose as high as 8 km
(26,200 ft) a.s.l. and drifted 625 km E. The Aviation Color Code was
briefly raised to Red (the highest level on a four-color scale) on 22
December, but then was lowered back to Orange.

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 white plumes rose 100-500 m above Sinabungâ??s summit
during 23-29 December. At 1751 on 28 December an ash plume rose 500 m above
the summit and drifted S. At 1227 on 29 December an ash plume drifted SW.
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/

Villarrica  | Chile  | 39.42Â°S, 71.93Â°W  | Summit elev. 2847 m

POVI reported that increased seismicity, more intense crater incandescence,
and a notable sulfur odor was noted at Villarrica during 18-19 December.
Minor ash emissions rose to low heights above the crater rim on 22
December. The Alert Level remained at Yellow, the second lowest level on a
four-color scale. ONEMI maintained an Alert Level Yellow (the middle level
on a three-color scale) for the municipalities of Villarrica, PucÃ³n (16 km
N), Curarrehue, the commune of Panguipulli, and the exclusion zone for the
public of 500 m around the crater.

Geologic Summary. Glacier-clad Villarrica, one of Chile's most active
volcanoes, rises above the lake and town of the same name. It is the
westernmost of three large stratovolcanoes that trend perpendicular to the
Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A
2-km-wide caldera that formed about 3500 years ago is located at the base
of the presently active, dominantly basaltic to basaltic-andesitic cone at
the NW margin of the Pleistocene caldera. More than 30 scoria cones and
fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that
have extended up to 20 km from the volcano were produced during the
Holocene. Lava flows up to 18 km long have issued from summit and flank
vents. Historical eruptions, documented since 1558, have consisted largely
of mild-to-moderate explosive activity with occasional lava effusion.
Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its
flanks.

Sources: Proyecto ObservaciÃ³n Villarrica Internet (POVI) http://www.povi.cl/
;

Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)
http://www.onemi.cl/;

Servicio Nacional de GeologÃa y MinerÃa (SERNAGEOMIN)
http://www.sernageomin.cl/

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

GeoNet reported that beginning around 1500 on 29 December a series of small
steam explosions at Whakaari/White Island were recorded for about 30
minutes by local seismic and acoustic instruments. Vigorous steam plumes
rising from the main vents were observed in webcam images. Ash was not
evident in satellite images though ash may have been present in the plumes
near the vent. The Volcanic Alert Level remained at 1 and the Aviation
Color Code remained at Green.

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 http://www.geonet.org.nz/

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