Smithsonian / USGS Weekly Volcanic Activity Report 3-9 January 2024

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


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


Smithsonian / USGS Weekly Volcanic Activity Report

3-9 January 2024



Sally Sennert - Weekly Report Editor (kuhns@xxxxxx)

URL: https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvl8ahr1d$ 
<https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6odhmsMBM$>





New Activity/Unrest: Grimsvotn, Iceland  | Kanaga, Andreanof Islands (USA)
| Lewotobi, Flores Island  | Marapi, Central Sumatra



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera  | Ebeko,
Paramushir Island (Russia)  | Gamalama, Halmahera  | Great Sitkin,
Andreanof Islands (USA)  | Iya, Flores Island  | Lewotolok, Lembata Island
| Merapi, Central Java  | Nevado del Ruiz, Colombia  | Purace, Colombia  |
Reventador, Ecuador  | Sabancaya, Peru  | Sangay, Ecuador  | Semeru,
Eastern Java  | Sheveluch, Central Kamchatka (Russia)  | Suwanosejima,
Ryukyu Islands (Japan)  | Ulawun, New Britain (Papua New Guinea)





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





Grimsvotn  | Iceland  | 64.416°N, 17.316°W  | Summit elev. 1719 m



A brief seismic swarm at Grímsvötn was recorded by the seismic network
beginning at 1600 on 4 January, prompting Icelandic Meteorological Office
(IMO) to raise the Aviation Color Code to Yellow (the second level on a
four-color scale). The swarm consisted of seven earthquakes with magnitudes
above 1, which was considered unusual. Since the beginning of December
there had been evidence of water drainage from the lake; the earthquakes
may have been related to the drainage, but it was not confirmed. Activity
did not escalate on 5 January and only one M 0.6 earthquake was detected.
The Aviation Color Code was lowered to Green. The report noted that seismic
activity at the volcano had been above background levels during the
previous four months.



Geologic Summary. Grímsvötn, Iceland's most frequently active volcano in
recent history, lies largely beneath the vast Vatnajökull icecap. The
caldera lake is covered by a 200-m-thick ice shelf, and only the southern
rim of the 6 x 8 km caldera is exposed. The geothermal area in the caldera
causes frequent jökulhlaups (glacier outburst floods) when melting raises
the water level high enough to lift its ice dam. Long NE-SW-trending
fissure systems extend from the central volcano. The most prominent of
these is the noted Laki (Skaftar) fissure, which extends to the SW and
produced the world's largest known historical lava flow in 1783. The 15 km3
basaltic Laki lavas were erupted over 7 months from a 27-km-long fissure
system. Extensive crop damage and livestock losses caused a severe famine
that resulted in the loss of one-fifth of the population of Iceland.



Source: Icelandic Meteorological Office (IMO) https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvgt1DxPM$ 
<https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6otOlLQrE$>





Kanaga  | Andreanof Islands (USA)  | 51.923°N, 177.168°W  | Summit elev.
1307 m



AVO reported that unrest at Kanaga continued during 3-9 January; no new
eruptive activity was evident in satellite and webcam images. Small daily
earthquakes were detected until 2 January when a storm-related power
failure took local monitoring data offline. Satellite radar images showed
that large NW-SE-trending fractures intersecting the summit crater had
likely formed around the time of the 18 December explosive event. The
Volcano Alert Level remained at Advisory (the second level on a four-level
scale) and the Aviation Color Code remained at Yellow (the second color on
a four-color scale).



Geologic Summary. Symmetrical Kanaga stratovolcano is situated within the
Kanaton caldera at the northern tip of Kanaga Island. The caldera rim forms
a 760-m-high arcuate ridge south and east of Kanaga; a lake occupies part
of the SE caldera floor. The volume of subaerial dacitic tuff is smaller
than would typically be associated with caldera collapse, and deposits of a
massive submarine debris avalanche associated with edifice collapse extend
nearly 30 km to the NNW. Several fresh lava flows from historical or late
prehistorical time descend the flanks of Kanaga, in some cases to the sea.
Historical eruptions, most of which are poorly documented, have been
recorded since 1763. Kanaga is also noted petrologically for ultramafic
inclusions within an outcrop of alkaline basalt SW of the volcano.
Fumarolic activity occurs in a circular, 200-m-wide, 60-m-deep summit
crater and produces vapor plumes sometimes seen on clear days from Adak, 50
km to the east.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvmcSHVgx$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oo-jcqS8$>





Lewotobi  | Flores Island  | 8.542°S, 122.775°E  | Summit elev. 1703 m



PVMBG reported that the eruption at Lewotobiâ??s Laki-laki volcano from a
fissure on the upper NNW flank and from a vent on the upper SSE flank was
ongoing during 3-9 January. White plumes rose 300-1,000 m above the summit
and drifted SW and W during 3-5 December. During the rest of the week
white-and-gray or gray-to-brown ash plumes rose 1-1.5 km above the summit
and drifted NW, N, and NE. The ash plumes were sometimes dense.



Masks had been distributed in Hokeng Jaya, Pululera, Klatanlo, and Nawakote
in the district of Wulanggitan and the village of Dulempari in the district
of Bura after the eruption began in late December and residents were
encouraged to wear them when outside to minimize ash inhalation. On 1
January as many as 1,185 residents of Boru Village and 328 residents in the
Konga Village area self-evacuated to several other locations including
relativesâ?? homes and evacuation posts. Ash fell in several areas in the
Wulanggitan and Bura districts. Badan Penanggulangan Bencana Daerah (BPBD)
East Flores Regency mobilized and provided residents with essentials
including mobile kitchens, food, tents, and cleaned ash off roadways. By 4
January a total of 3,898 people had evacuated. The Frans Xavier Seda
Airport in Sikka District closed on 1 January due to thick ash deposits on
the runways; it remained closed as of 9 January.



Activity intensified during the evening of 9 January. Incandescent material
was ejected from the summit and lava flows from the NNW-flank fissure
descended the NW flank. At 2300 the Alert Level was raised to 4 (on a scale
of 1-4) and the public was warned to stay 4 km away from the Perempuan and
Laki-laki craters and an additional 5 km from the NNW flanks of Laki-laki.



Geologic Summary. The Lewotobi edifice in eastern Flores Island is composed
of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan
stratovolcanoes (the "husband and wife"). Their summits are less than 2 km
apart along a NW-SE line. The conical Laki-laki to the NW has been
frequently active during the 19th and 20th centuries, while the taller and
broader Perempuan has had observed eruptions in 1921 and 1935. Small lava
domes have grown during the 20th century in both of the summit craters,
which are open to the north. A prominent cone, Iliwokar, occurs on the E
flank of Perampuan.



Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>
;

Badan Nacional Penanggulangan Bencana (BNPB) https://urldefense.com/v3/__http://www.bnpb.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvmBO1mkr$ 
<https://urldefense.com/v3/__http://www.bnpb.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6olhgFyxA$>
;

Badan Penanggulangan Bencana Daerah Provinsi Jawa Timur (East Java BPBD)
https://urldefense.com/v3/__https://web.bpbd.jatimprov.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvj8iif0Q$ 
<https://urldefense.com/v3/__https://web.bpbd.jatimprov.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oq1sjXeM$>
;

Directorate General Of Civil Aviation, Ministry Of Transportation Republic
Of Indonesia
https://urldefense.com/v3/__https://web.archive.org/web/20170516092636/http:/*hubud.dephub.go.id/?en__;Lw!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvjqViljZ$ 
<https://urldefense.com/v3/__https://web.archive.org/web/20170516092636/http:/hubud.dephub.go.id/?en__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6ooQPlDYA$>





Marapi  | Central Sumatra  | 0.38°S, 100.474°E  | Summit elev. 2885 m



PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing at
Verbeek Crater during 3-9 January. White plumes rose 300-350 m above the
summit and drifted S and SW on 4 January. White-and-gray ash plumes rose
150-600 m above the summit and drifted S, SW, N, and NE during 5-8 January.



PVMBG reevaluated instrumental data and visual observations at Marapi and
concluded that activity was continuing at high levels; at 1800 on 9 January
they raised the Alert Level to 3 (on a scale of 1-4) and warned the public
to stay 4.5 km away from Verbeek Crater. They noted that ongoing high
seismicity and increasing numbers of low-frequency and deep volcanic
earthquakes indicated that magma continued to be supplied at depth.
Incandescence at the crater and the ejection of incandescent material after
the 3 December eruption indicated that the eruption style had change from
phreatic to magmatic; sulfur dioxide emissions measured from satellite were
at high levels.



Geologic Summary. Gunung Marapi, not to be confused with the better-known
Merapi volcano on Java, is Sumatra's most active volcano. This massive
complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the
Padang Highlands. A broad summit contains multiple partially overlapping
summit craters constructed within the small 1.4-km-wide Bancah caldera. The
summit craters are located along an ENE-WSW line, with volcanism migrating
to the west. More than 50 eruptions, typically consisting of
small-to-moderate explosive activity, have been recorded since the end of
the 18th century; no lava flows outside the summit craters have been
reported in historical time.



Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>







Ongoing Activity







Aira  | Kyushu (Japan)  | 31.5772°N, 130.6589°E  | Summit elev. 1117 m



JMA reported ongoing activity at Minamidake Crater (Aira Calderaâ??s
Sakurajima volcano) during 1-8 January with incandescence at the crater
observed nightly. Small eruptive events were occasionally recorded during
the week. The Alert Level remained at 3 (on a 5-level scale), and the
public was warned to stay 2 km away from both craters.



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 caldera, along
with several post-caldera cones. The construction of Sakurajima began about
13,000 years ago on the southern rim and built an island that was joined to
the Osumi Peninsula during the major explosive and effusive eruption of
1914. Activity at the Kitadake summit cone ended about 4,850 years ago,
after which eruptions took place at Minamidake. Frequent eruptions since
the 8th century have deposited ash on the city of Kagoshima, located across
Kagoshima Bay only 8 km from the summit. The largest recorded eruption took
place during 1471-76.



Source: Japan Meteorological Agency (JMA) https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvnbuW7no$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oPBYF00k$>





Dukono  | Halmahera  | 1.6992°N, 127.8783°E  | Summit elev. 1273 m



PVMBG reported that the eruption at Dukono was ongoing during 3-9 January.
Gray-and-white ash plumes rose as high as 4 km above the summit and drifted
SW on 3 January. White-and-gray ash plumes rose 100-1,900 m above the
summit and drifted W and SW during 4 and 6-8 January. The Alert Level
remained at Level 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, have occurred since 1933. During a major
eruption in 1550 CE, a lava flow filled in the strait between Halmahera and
the N-flank Gunung Mamuya cone. 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) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>





Ebeko  | Paramushir Island (Russia)  | 50.686°N, 156.014°E  | Summit elev.
1103 m



KVERT reported that moderate explosive activity was ongoing at Ebeko during
28 December 2023-4 January 2024. According to volcanologists in
Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 30-31
December generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l
and drifted SE. The Aviation Color Code remained at Orange (the third level
on a four-color scale). Dates are UTC; specific events are in local time
where noted.



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)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvjp5faJP$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6opLTvcpM$>





Gamalama  | Halmahera  | 0.81°N, 127.3322°E  | Summit elev. 1714 m



Although there was no eruptive activity reported at Gamalama, in a 4
January press release PVMBG noted that the number of daily deep volcanic
earthquakes had significantly increased. The seismic network recorded a
total of 45 deep volcanic earthquakes during 0000-0600 on 4 January; an
average of 2-3 events per day had been recorded since January 2023. Diffuse
white plumes only rose as high as 120 m above the summit during the
previous month whereas typically they can rise as high as 300 m. PVMBG
noted that the most likely hazard would be a phreatic event that could
ejected material within the 1.5-km radius, though ash may be carried
farther by wind. The Alert Level remained at 2 (on a scale of 1-4);
visitors and residents were warned not to approach the crater within a
1.5-km radius.



Geologic Summary. Gamalama is a near-conical stratovolcano that comprises
the entire island of Ternate off the western coast of Halmahera, and is one
of Indonesia's most active volcanoes. The island was a major regional
center in the Portuguese and Dutch spice trade for several centuries, which
contributed to the extensive documentation of activity. Three cones,
progressively younger to the north, form the summit. Several maars and
vents define a rift zone, parallel to the Halmahera island arc, that cuts
the volcano; the S-flank Ngade maar formed after about 14,500â??13,000 cal.
BP (Faral et al., 2022). Eruptions, recorded frequently since the 16th
century, typically originated from the summit craters, although flank
eruptions have occurred in 1763, 1770, 1775, and 1962-63.



Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>





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



AVO reported that a radar image of Great Sitkin showed continuing growth of
a thick flow in the summit crater with expansion to the E; effusion likely
continued during 3-9 January. Radial cracks around the central vent widened
and pushed material 15 m N. Weather clouds often obscured views of the
volcano. Seismicity was low, though beginning during 2-4 January web
cameras and seismic data were offline due to a power failure. The Volcano
Alert Level remained at Watch (the third level on a four-level scale) and
the Aviation Color Code remained at Orange (the third color on a four-color
scale).



Geologic Summary. The Great Sitkin volcano forms much of the northern side
of Great Sitkin Island. A younger 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
older edifice and produced a submarine debris avalanche. Deposits from this
and an even 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. 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!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvmcSHVgx$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oo-jcqS8$>





Iya  | Flores Island  | 8.891°S, 121.641°E  | Summit elev. 618 m



PVMBG reported that during 1-31 December diffuse white plumes rose as high
as 80 m above Iyaâ??s summit. During most of that period seismicity was at
normal levels and characterized by both deep and shallow volcanic
earthquakes. A total of 55 deep volcanic earthquakes were recorded during
the month with 12 of them recorded during 30-31 December, signifying a
significant increase during that period. The Alert Level was remained at 1
(on a scale of 1-4), and the public was warned to limit activity near the
active crater area.



Geologic Summary. Gunung Iya is the southernmost of a group of three
volcanoes comprising a small peninsula south of the city of Ende on central
Flores Island. The cones to the north, Rooja and Pui, appear to be slightly
older and have not shown historical activity, although Pui has a youthful
profile (a reported 1671 eruption of Pui was considered to have originated
from Iya volcano). Iya, whose truncated southern side drops steeply to the
sea, has had numerous moderate explosive eruptions during historical time.



Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>





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



PVMBG reported that the eruption at Lewotolok continued during 3-9 January.
White-and-gray ash plumes rose 300-350 m above the summit and drifted NW on
3 and 6 January. White steam-and-gas plumes rose 400-500 m above the summit
and drifted NW on the other days. Incandescent lava was occasionally
ejected about the vent. 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 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!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>





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



BPPTKG reported that the eruption at Merapi (on Java) continued during 29
December 2023-4 January 2024. The SW lava dome produced a total of 83 lava
avalanches that descended the S and SW flanks; six traveled S as far as 1.4
km down the upper part of the Boyong drainage and the other 77 traveled SW
as far as 2 km down the upper part of the Bebeng drainage. Two pyroclastic
flows descended the Bebeng, traveling as far as 1.8 km. Morphological
changes to the SW lava dome identified in webcam images were due to
continuing collapses of material. The Alert Level remained at 3 (on a scale
of 1-4), and the public was warned to stay 3-7 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!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvvr8wdmf$ 
<https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o6f7fqOc$>





Nevado del Ruiz  | Colombia  | 4.892°N, 75.324°W  | Summit elev. 5279 m



Servicio Geológico Colombianoâ??s (SGC) Observatorio Vulcanológico y
Sismológico de Manizales reported that eruptive activity at Nevado del Ruiz
continued at moderate levels during 2-8 January. Seismic events indicating
rock fracturing increased in both number an intensity. These events were
located in areas up to 4 km in various directions from Arenas Crater at
depths of 1-7 km. The seismic activity was most notable on 3 and 5 January;
the largest earthquake, a M 3.9, was recorded at 1103 on 3 January and felt
by officials of the Parque Nacional Natural Los Nevados, SGC personnel in
the field, and residents in Manizales (27 km NW). Seismicity associated
with ash-and-gas emissions decreased in both size and number. The maximum
height of the ash-and-gas emissions was 1.8 km above the summit, recorded
on 6 January. Emissions during the week drifted NW, W, and SW, causing
ashfall near the volcano and occasionally in Manizales. The Alert Level
remained at Yellow, Level III (the second level on a four-level scale), and
the public was warned to stay out of the restricted areas around Arenas
Crater.



Geologic Summary. Nevado del Ruiz is a broad, glacier-covered volcano in
central Colombia that covers more than 200 km2. Three major edifices,
composed of andesitic and dacitic lavas and andesitic pyroclastics, have
been constructed since the beginning of the Pleistocene. The modern cone
consists of a broad cluster of lava domes built within the caldera of an
older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit.
The prominent La Olleta pyroclastic cone located on the SW flank may also
have been active in historical time. Steep headwalls of massive landslides
cut the flanks. Melting of its summit icecap during historical eruptions,
which date back to the 16th century, has resulted in devastating lahars,
including one in 1985 that was South America's deadliest eruption.



Source: Servicio Geológico Colombiano (SGC)
https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvo6qSJh4$ 
<https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oR99jqQM$>





Purace  | Colombia  | 2.32°N, 76.4°W  | Summit elev. 4650 m



Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico
Colombiano (SGC) reported increased unrest at Puracé on 5 January. A sudden
increase in carbon dioxide emissions was detected during the morning and
decreased through the day; increased gas emissions were visible in webcam
images during the afternoon. Seismicity increased at 1450 and continued at
high levels at least through 1715, the time the report was issued. The
earthquake signals indicated fluid movement, had low magnitudes, and were
located less than 2 km below the summit. The Alert Level remained at Yellow
(the second level on a four-color scale).



Geologic Summary. Puracé in Colombia consists of an andesitic stratovolcano
with a 500-m-wide summit crater constructed over a dacitic shield volcano.
It lies at the NW end of a volcanic massif opposite Pan de Azúcar
stratovolcano, 6 km SE. A NW-SE-trending group of seven cones and craters,
Los Coconucos, lies between the two larger edifices. Frequent explosive
eruptions in the 19th and 20th centuries have modified the morphology of
the summit crater. The largest eruptions occurred in 1849, 1869, and 1885.



Source: Servicio Geológico Colombiano (SGC)
https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvo6qSJh4$ 
<https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oR99jqQM$>





Reventador  | Ecuador  | 0.077°S, 77.656°W  | Summit elev. 3562 m



IG-EPN reported that a moderate eruption at Reventador was ongoing during
2-9 January. Seismicity was characterized by 37-58 daily explosions,
long-period earthquakes, harmonic tremor, and tremor associated with
emissions. Several ash-and-gas plumes rose as high as 1.3 km above the
crater rim and drifted S, SW, W, and NW, though cloudy conditions often
prevented views. Crater incandescence was occasionally visible during both
overnight and morning hours; incandescent material was ejected 200-300 m
above the crater and avalanches of incandescent material descended the
flanks as far as 600 m from the summit during 6-9 January. A small lahar
was recorded on 6 January. Secretaría de Gestión de Riesgos maintained the
Alert Level at Orange (the second highest level on a four-color scale).



Geologic Summary. Volcán El Reventador is the most frequently active of a
chain of Ecuadorian volcanoes in the Cordillera Real, well east of the
principal volcanic axis. The forested, dominantly andesitic stratovolcano
has 4-km-wide avalanche scarp open to the E formed by edifice collapse. A
young, unvegetated, cone rises from the amphitheater floor to a height
comparable to the rim. It has been the source of numerous lava flows as
well as explosive eruptions visible from Quito, about 90 km ESE. Frequent
lahars in this region of heavy rainfall have left extensive deposits on the
scarp slope. The largest recorded eruption took place in 2002, producing a
17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and
lava flows from summit and flank vents.



Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvoa8Ce_Y$ 
<https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6ofMbdLcU$>
;

Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvtPDR6SR$ 
<https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oAmcOxmU$>





Sabancaya  | Peru  | 15.787°S, 71.857°W  | Summit elev. 5960 m



Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya
continued at moderate levels during 3-7 January with a daily average of 61
explosions. Gas-and-ash plumes rose as high as 1.7 km above the summit and
drifted less than 10 km NW, W, and SW. Thermal anomalies over the lava dome
in the summit crater were identified in satellite data. Slight inflation
was detected near the Hualca Hualca sector (4 km N). The Alert Level
remained at Orange (the third level on a four-color scale) and the public
were warned to stay outside of a 12 km radius.



Geologic Summary. Sabancaya, located in the saddle NE of Ampato and SE of
Hualca Hualca volcanoes, is the youngest of these volcanic centers and the
only one to have erupted in historical time. The oldest of the three,
Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene
age. The name Sabancaya (meaning "tongue of fire" in the Quechua language)
first appeared in records in 1595 CE, suggesting activity prior to that
date. Holocene activity has consisted of Plinian eruptions followed by
emission of voluminous andesitic and dacitic lava flows, which form an
extensive apron around the volcano on all sides but the south. Records of
historical eruptions date back to 1750.



Source: Instituto Geofísico del Perú (IGP) https://urldefense.com/v3/__http://www.igp.gob.pe/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvv-p-VOU$ 
<https://urldefense.com/v3/__http://www.igp.gob.pe/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o5oksgYU$>





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



IG-EPN reported a high level of eruptive activity at Sangay during 1-9
January, with seismic stations recording 173-583 daily explosions.
Ash-and-gas plumes were visible, in both webcam and satellite images,
rising as high as 1.5 km above the crater rim and drifting SW during 1-5
January. Webcam images showed incandescence at the summit vent and
incandescent material descending the SE flank as far as 1.8 km from the
crater. Beginning at 1536 on 6 January a series of explosions and ash
emissions were visible in webcam images with ash-and-gas plumes rising 3 km
above the summit and drifting NW. The activity continued into the late
afternoon and intensified; ash plumes rose as high as 8 km above the summit
and drifted W, NW, and N. Ashfall was reported in several towns downwind,
including San Antonio, Pancún, Cebadas (35 km WNW), Gualiñag, Guargallá
Chico, Guamote (40 km WNW), Pungalá (25 km NW), and Chunchi (73 km SW) in
the province of Chimborazo, Chillanes (80 km W) in the province of Bolívar,
Montalvo (106 km WNW), Babahoyo (135 km WNW), Ventanas, Pueblo Viejo (141
km NW), Vinces (165 km WNW), and Baba (152 km WNW) in the province of El
Oro, and Palestina (185 km WNW) in the province of Guayas. Several
pyroclastic flows descended the SE drainage during 6-7 January. Ash-and-gas
plumes rose 400-800 m above the summit during 7-8 January. During the
morning of 8 January, a pyroclastic flow descended the SE drainage and
minor ashfall was reported in the Guamote-Chimborazo canton. Cloudy weather
prevented views during 8-9 January, though crater incandescence was
observed overnight. Secretaría de Gestión de Riesgos maintained the Alert
Level at Yellow (the second highest level on a four-color scale).



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



Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvoa8Ce_Y$ 
<https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6ofMbdLcU$>
;

Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvtPDR6SR$ 
<https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oAmcOxmU$>





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



PVMBG reported that eruptive activity continued at Semeru during 3-9
January. Daily white-and-gray ash plumes that were sometimes dense rose
400-1,200 m above the summit and drifted S, SW, and W. The Alert Level
remained at 3 (third highest on a scale of 1-4). The public was warned to
stay at least 5 km away from the summit in all directions, 13 km from the
summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17
km from the summit, and to avoid other drainages including the Bang,
Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.



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) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqIMcgyy$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6o7zhrq8E$>





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



KVERT reported that the eruption at Sheveluch continued during 28 December
2023-4 January 2024 with a daily thermal anomaly identified in satellite
images. The Aviation Color Code remained at Orange (the third level on a
four-color scale). Dates are based on UTC times; specific events are in
local time where noted.



Geologic Summary. The high, isolated massif of Sheveluch volcano (also
spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya
volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's
largest and most active volcanic structures, with at least 60 large
eruptions during the Holocene. 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 occur on its outer flanks. The
Molodoy Shiveluch lava dome complex was constructed during the Holocene
within the large open caldera; Holocene lava dome extrusion also took place
on the flanks of Stary Shiveluch. 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!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvjp5faJP$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6opLTvcpM$>





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



JMA reported that the eruption at Suwanosejima's Ontake Crater continued
during 1-8 January. No explosions were detected, though large blocks were
ejected as far as 400 m from the vent. Ash plumes rose 1-2 km above the
crater rim during 1-2, 6, and 8 January and drifted in multiple directions.
Ash emissions were continuous during 0157-0620 and 0834-2235 on 2 January.
The Alert Level remained at 2 (on a 5-level scale) and the public was
warned to stay at least 1 km away from the crater.



Geologic Summary. The 8-km-long island of Suwanosejima in the northern
Ryukyu Islands consists of an andesitic stratovolcano with two active
summit craters. The summit is truncated by a large breached crater
extending to the sea on the E flank that was formed by edifice collapse.
One of Japan's most frequently active volcanoes, it was in a state of
intermittent Strombolian activity from Otake, the NE summit crater, between
1949 and 1996, after which periods of inactivity lengthened. The largest
recorded eruption took place in 1813-14, when thick scoria deposits covered
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 an open collapse
scarp extending 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!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvnbuW7no$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oPBYF00k$>





Ulawun  | New Britain (Papua New Guinea)  | 5.05°S, 151.33°E  | Summit
elev. 2334 m



Rabaul Volcano Observatory (RVO) reported that activity at Ulawun was low
during 6 December 2023-9 January 2024. During periods of good visibility
white steam plumes of variable densities were seen rising from the summit
crater. On 19 December visibility was poor, though during a brief clear
period, observers noted brown-tinged steam plumes. On 31 December residents
of Noau Village photographed dense brown ash plumes rising a few hundred
meters above the summit and drifting W, and a small pyroclastic flow
descending the NNE flank. The Alert Level remained at Stage 1 (on the
four-level scale).



Geologic Summary. The symmetrical basaltic-to-andesitic Ulawun
stratovolcano is the highest volcano of the Bismarck arc, and one of Papua
New Guinea's most frequently active. The volcano, also known as the Father,
rises above the N coast of the island of New Britain across a low saddle NE
of Bamus volcano, the South Son. The upper 1,000 m is unvegetated. A
prominent E-W escarpment on the south may be the result of large-scale
slumping. Satellitic cones occupy the NW and E flanks. A steep-walled
valley cuts the NW side, and a flank lava-flow complex lies to the south of
this valley. Historical eruptions date back to the beginning of the 18th
century. Twentieth-century eruptions were mildly explosive until 1967, but
after 1970 several larger eruptions produced lava flows and basaltic
pyroclastic flows, greatly modifying the summit crater.



Source: Rabaul Volcano Observatory (RVO)
https://urldefense.com/v3/__https://webdev.datec.net.pg/geohazards/category/volcanoes/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvqQbN9ow$ 
<https://urldefense.com/v3/__https://webdev.datec.net.pg/geohazards/category/volcanoes/__;!!IKRxdwAv5BmarQ!cz_QJ7idIUZ-e2o5dECafXInXkcNHbWfQymQYASlekJP_8weXa7yvIKqqW2Jowr-bR6oFIBT_SI$>


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



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 - https://urldefense.com/v3/__http://pdx.edu/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvrwlsscj$ 

GVP - https://urldefense.com/v3/__https://volcano.si.edu/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvv5xwoGK$ 

IAVCEI - https://urldefense.com/v3/__https://www.iavceivolcano.org/__;!!IKRxdwAv5BmarQ!cgg1F5OmgWt6DF_i-KkN-tSI5iEeKd1un0K8950vGnPNFG0OuDGy1EfTFRGVwc4ZIJ94ED3jvoxCML3B$ 


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End of Volcano Digest - 9 Jan 2024 to 11 Jan 2024 (#2024-3)
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