Smithsonian / USGS Weekly Volcanic Activity Report 10-16 January 2024

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


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


Smithsonian / USGS Weekly Volcanic Activity Report

10-16 January 2024



Sally Sennert - Weekly Report Editor (kuhns@xxxxxx)

URL: https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCyCBA369$ 
<https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYcl82TNUN4$>





New Activity/Unrest: Ahyi, Mariana Islands (USA)  | Ambrym, Vanuatu  |
Grimsvotn, Iceland  | Lewotobi, Flores Island  | Marapi, Central Sumatra  |
Reykjanes, Reykjanes Peninsula



Ongoing Activity: Aira, Kyushu (Japan)  | Bulusan, Luzon (Philippines)  |
Dukono, Halmahera  | Ebeko, Paramushir Island (Russia)  | Great Sitkin,
Andreanof Islands (USA)  | Lewotolok, Lembata Island  | Merapi, Central
Java  | Poas, Costa Rica  | Popocatepetl, Mexico  | Rincon de la Vieja,
Costa Rica  | Sangay, Ecuador  | Semeru, Eastern Java  | Sheveluch, Central
Kamchatka (Russia)  | Suwanosejima, Ryukyu Islands (Japan)





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





Ahyi  | Mariana Islands (USA)  | 20.42°N, 145.03°E  | Summit elev. -75 m



Signs of unrest at Ahyi Seamount were observed during the previous few
weeks. Plumes of discolored water drifting as far as 10 km from the vent
were identified in satellite data on 24 December 2023 and again on 4 and 10
January 2024. Hydroacoustic arrays located on Wake Island did not record
any significant signals, though submarine plumes have been observed in the
past without clear hydroacoustic evidence. The Aviation Color Code was
raised to Yellow (the second level on a four-color scale) and the Volcano
Alert Level was raised to Advisory (the second level on a four-level scale)
on 14 January because the likelihood of an eruption had increased. No
unusual activity observed in satellite data during 15-17 January.



Geologic Summary. Ahyi seamount is a large conical submarine volcano that
rises to within 75 m of the ocean surface ~18 km SE of the island of
Farallon de Pajaros in the northern Marianas. Water discoloration has been
observed there, and in 1979 the crew of a fishing boat felt shocks over the
summit area, followed by upwelling of sulfur-bearing water. On 24-25 April
2001 an explosive eruption was detected seismically by a station on
Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15
km) at a location near the southern base of Ahyi. An eruption in April-May
2014 was detected by NOAA divers, hydroacoustic sensors, and seismic
stations.



Source: US Geological Survey https://urldefense.com/v3/__https://www.usgs.gov/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC8ypEuYv$ 
<https://urldefense.com/v3/__https://www.usgs.gov/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYcl8v6Euq8$>





Ambrym  | Vanuatu  | 16.25°S, 168.12°E  | Summit elev. 1334 m



The Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that at
2217 on 13 January an eruption began at Ambrymâ??s Benbow Crater based on
webcam and seismic data. The eruption was characterized by a loud
explosion, intense incandescence at the crater, and gas-and-steam
emissions. The Alert Level was raised from 1 to 3 (on a scale of 0-5) and
the public to stay 2 km away from Benbow Crater and 4 km away from Marum
Crater, and additionally to stay 500 m away from the ground cracks created
by the December 2018 eruption. Sulfur dioxide emissions measured using
satellite data were 1,116 tons per day on 14 January. Activity decreased
during 15-17 January based on webcam images, seismic data, and field
observations. Gas, steam, and ash emissions had decreased, and crater
incandescence was dim or not visible at all. The Alert Level was lowered to
2 on 17 January.



Geologic Summary. Ambrym, a large basaltic volcano with a 12-km-wide
caldera, is one of the most active volcanoes of the New Hebrides Arc. A
thick, almost exclusively pyroclastic sequence, initially dacitic then
basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera
was formed during a major Plinian eruption with dacitic pyroclastic flows
about 1,900 years ago. Post-caldera eruptions, primarily from Marum and
Benbow cones, have partially filled the caldera floor and produced lava
flows that ponded on the floor or overflowed through gaps in the caldera
rim. Post-caldera eruptions have also formed a series of scoria cones and
maars along a fissure system oriented ENE-WSW. Eruptions have apparently
occurred almost yearly during historical time from cones within the caldera
or from flank vents. However, from 1850 to 1950, reporting was mostly
limited to extra-caldera eruptions that would have affected local
populations.



Source: Vanuatu Meteorology and Geohazards Department (VMGD)
https://urldefense.com/v3/__http://www.geohazards.gov.vu/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCzu2ATSJ$ 
<https://urldefense.com/v3/__http://www.geohazards.gov.vu/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclnbrxLHo$>





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



IMO reported that at 0653 on 11 January a M 4.3 earthquake occurred at
Grímsvötn and was the largest earthquake recorded at the volcano since
measurements started in 1991. A gradual increase in tremor was recorded at
Mt. Grímsfjall, which rises about 300 m above the flat ice shelf over the
subglacial lake, since 7 January and the water level in the Gígjukvísl
River began to rise on 10 January. IMO noted that a jökulhlaup had likely
begun and that the earthquake was in response to pressure release from the
flood. The Aviation Color Code was raised to Yellow (the second level on a
four-color scale) reflecting the slight increase in the likelihood of an
eruption being triggered by the flood. IMO noted that the last eruption was
in 2004; since then, 12 jökulhlaups had occurred with no eruptions.



Water levels in the Gígjukvísl River steadily and significantly increased
during 11-12 January and the river widened; the river rose 70 cm based on
data from a stream gauge at the bridge crossing Highway 1. The water level
stabilized during 13-14 January, signifying that it had reached peak flow,
and was then expected to subside. Around midnight on 15 January the
seismometer at Grímsfjall began recording increased tremor, which was
likely due to increased geothermal activity and is commonly observed at the
end of a jökulhlaup.



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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCyx95Dwl$ 
<https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclXaZbvR4$>





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



PVMBG reported that the eruption at Lewotobiâ??s Laki-laki volcano was
ongoing during 10-16 January. Dense white-and-gray or white, gray, and
brown ash plumes rose as high as 2 km above the summit and drifted N and
NE. Lava flows from the summit crater continued to advance down the N flank
and were about 2 km long by 11 January. Rumbling was reported on 13
January. On 14 January as many as four pyroclastic flows traveled up to 1
km down the NE, N, and NNW flanks and lava avalanches traveled 1.5-2 km
down the NE flank, according to news articles. Incandescent avalanches of
material and accompanying pyroclastic flows traveled as far as 1.5 km N on
15 January. Incandescent avalanches also traveled 2-3 km NE and 1 km NNE.
The exclusion zone was increased to 5 km from the Laki-laki Crater and 6 km
from the crater on the N and NE flanks during the evening of 16 January.
The Alert Level remained at 4 (the highest level on a scale of 1-4).



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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC2cxzImG$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclBrb4sSY$>
;

Antara News
https://urldefense.com/v3/__https://www.antaranews.com/berita/3918537/pvmbg-perluas-radius-larangan-beraktivitas-antisipasi-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC_0tlsyd$ 
<https://urldefense.com/v3/__https://www.antaranews.com/berita/3918537/pvmbg-perluas-radius-larangan-beraktivitas-antisipasi-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclM52Ui8k$>
;

Antara News
https://urldefense.com/v3/__https://www.antaranews.com/berita/3916827/pvmbg-ingatkan-warga-waspadai-aliran-lahan-hujan-dari-gunung-lewotobi__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCwbeecin$ 
<https://urldefense.com/v3/__https://www.antaranews.com/berita/3916827/pvmbg-ingatkan-warga-waspadai-aliran-lahan-hujan-dari-gunung-lewotobi__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclDz6nH6g$>
;

Antara News
https://urldefense.com/v3/__https://www.antaranews.com/berita/3915531/pvmbg-dalam-enam-jam-gunung-lewotobi-erupsi-12-kali__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCwYZ_rde$ 
<https://urldefense.com/v3/__https://www.antaranews.com/berita/3915531/pvmbg-dalam-enam-jam-gunung-lewotobi-erupsi-12-kali__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclJlWf6cE$>
;

Antara News
https://urldefense.com/v3/__https://www.antaranews.com/berita/3915009/pvmbg-catat-terjadi-awan-panas-guguran-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCwBYRp7A$ 
<https://urldefense.com/v3/__https://www.antaranews.com/berita/3915009/pvmbg-catat-terjadi-awan-panas-guguran-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclWk3FdRw$>
;

Antara News
https://urldefense.com/v3/__https://www.antaranews.com/berita/3914013/pvmbg-imbau-warga-flores-timur-waspada-guguran-lava-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC8T7-S-F$ 
<https://urldefense.com/v3/__https://www.antaranews.com/berita/3914013/pvmbg-imbau-warga-flores-timur-waspada-guguran-lava-erupsi-lewotobi__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYcln723tN0$>





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 10-16 January. Dense, white-and-gray ash plumes rose
as high as 1.5 km above the summit and drifted NW, W, and SW during 11-15
January. Weather conditions sometimes prevented views of the volcano. The
Alert Level remained at 3 (on a scale of 1-4), and the public was warned to
stay 4.5 km away from Verbeek Crater.



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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC2cxzImG$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclBrb4sSY$>





Reykjanes  | Reykjanes Peninsula  | 63.817°N, 22.717°W  | Summit elev. 140 m



IMO reported that a seismic swarm began near the older Sundhnúkagígar
crater row on the Reykjanes peninsula around 0230 on 14 January. Both GPS
data and borehole pressure readings indicated that magma was moving. IMO
raised the Aviation Color Code to Orange (the third level on a four-color
scale), noting an increased likelihood of an eruption. The locations of the
earthquakes shifted towards the town of Grindavík where, according to
Almannavarnadeild ríkislögreglustjóra (National Commissioner of the
Icelandic Police and Department of Civil Protection and Emergency
Management), evacuations started around 0300.



A fissure eruption began at around 0757 just N of Grindavík, SE of
Hagafell, and was visible on webcams. The Aviation Color Code was raised to
Red, but then lowered back to Orange at 0826 because no ash was detected in
radar data. A Coast Guard helicopter was dispatched to investigate the
eruption site. A NE-SW-trending fissure was visible and notably lengthened
within about 10 minutes according to a news article. The fissure grew to
about 900 m long and crossed through the eastern part of a curving
E-W-oriented earthen berm built to deflect lava flows away from the town.
Lava fountaining occurred along the length of the fissure. Lava spread
perpendicular from the fissure and to the SW, covering the E half of the
berm, though the longest flow traveled WSW along the berm and away from the
town. Construction workers managed to reach their heavy equipment that was
being used to build the berm and drive them to safety away from the lava
flows. Lava covered part of Grindavíkurvegur road and overtopped a small
area of the berm at the road, flowing S.



A shorter second fissure that was about 100 m long opened at 1210 on 14
January to the SW of the first and S of the berm, about 200 m from the
Efrahópi neighborhood in Grindavík. Lava flows traveled S, entering the
town and setting at least three houses on fire. This fissure was no longer
active by 1640 on 15 January and the effusion rate at the larger, main
fissure had decreased. Seismicity and the rate of deformation had also
decreased, though deformation near the S part of the magmatic dike near
Grindavík continued to be detected. Displacement within the town was as
high as 1.4 m during 14-15 January; ground cracks had developed, and
existing ones had expanded. Thermal images from a 15 January drone flight
indicated that previously mapped fissures SW of Grindavík had significantly
enlarged. Lava effusion at the longer fissure was concentrated at two of
four main vents. Lava effusion at the main fissure ceased around 0100 on 16
January. Seismicity continued to decrease, though event locations indicated
that magma movement continued. Most of the seismic activity was
concentrated near Hagafell, close to the main fissure. IMO lowered the
Aviation Color Code to Yellow at 2105, noting the ongoing decline of
seismicity.



A man working on filling cracks in Grindavík fell into one of the cracks on
10 January and was unable to be located. Hundreds of rescue workers
searched for the man but due to unsafe conditions and landslides occurring
inside the crack the search was stopped on 12 January.



Geologic Summary. The Reykjanes volcanic system at the SW tip of the
Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level,
comprises a broad area of postglacial basaltic crater rows and small shield
volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous
with and is considered part of the Reykjanes volcanic system, which is the
westernmost of a series of four closely-spaced en-echelon fissure systems
that extend diagonally across the Reykjanes Peninsula. Most of the
subaerial part of the system (also known as the Reykjanes/Svartsengi
volcanic system) is covered by Holocene lavas. Subaerial eruptions have
occurred in historical time during the 13th century at several locations on
the NE-SW-trending fissure system, and numerous submarine eruptions dating
back to the 12th century have been observed during historical time, some of
which have formed ephemeral islands. Basaltic rocks of probable Holocene
age have been recovered during dredging operations, and tephra deposits
from earlier Holocene eruptions are preserved on the nearby Reykjanes
Peninsula.



Sources: Icelandic Meteorological Office (IMO) https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCyx95Dwl$ 
<https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclXaZbvR4$>
;

Almannavarnadeild ríkislögreglustjóra (National Commissioner of the
Icelandic Police and Department of Civil Protection and Emergency
Management) https://urldefense.com/v3/__https://www.almannavarnir.is/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC4Umwxh3$ 
<https://urldefense.com/v3/__https://www.almannavarnir.is/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclKjAlzFU$>
;

Icelandic National Broadcasting Service (RUV)
https://urldefense.com/v3/__https://www.ruv.is/english/2024-01-14-grindavik-eruptions-401887__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC4qoXkVH$ 
<https://urldefense.com/v3/__https://www.ruv.is/english/2024-01-14-grindavik-eruptions-401887__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclSs1gX2A$>
;

Independent
https://urldefense.com/v3/__https://www.independent.co.uk/world/grindavik-search-iceland-man-fall-crack-b2477811.html__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC8pMfMvB$ 
<https://urldefense.com/v3/__https://www.independent.co.uk/world/grindavik-search-iceland-man-fall-crack-b2477811.html__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYcl4w54_9s$>





Ongoing Activity





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



JMA reported ongoing eruptive activity at Minamidake Crater (Aira Calderaâ??s
Sakurajima volcano) during 8-15 January with incandescence at the crater
observed nightly. An explosion at 1552 on 9 January produced an ash plume
that rose as high as 1.2 km above the crater rim and drifted E and SE.
Small eruptive events were occasionally recorded during 12-15 January. 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCxsdlrmr$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclsXSNHqA$>





Bulusan  | Luzon (Philippines)  | 12.769°N, 124.056°E  | Summit elev. 1535 m



PHIVOLCS reported increased seismicity at Bulusan in a special advisory.
>From 0500 on 11 January to 1000 on 11 January the seismic network recorded
a total of 71 volcanic-tectonic earthquakes associated with rock
fracturing. The earthquakes were located at depths of 1-6 km beneath the S
flank. The largest event was a M 2.2. Diffuse gas plumes rose from the
summit crater and drifted W and SE. The Alert Level remained at 1 (the
second level on a scale of 0-5) and PHIVOLCS reminded the public not to
enter the 4-km-radius Permanent Danger Zone (PDZ) and to be vigilant within
the 2-km Extended Danger Zone (EDZ) on the SE flank.



Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed
along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera,
which was formed about 36,000 years ago. It lies at the SE end of the Bicol
volcanic arc occupying the peninsula of the same name that forms the
elongated SE tip of Luzon. A broad, flat moat is located below the
topographically prominent SW rim of Irosin caldera; the NE rim is buried by
the andesitic complex. Bulusan is flanked by several other large
intracaldera lava domes and cones, including the prominent Mount Jormajan
lava dome on the SW flank and Sharp Peak to the NE. The summit is
unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small
craters are located on the SE flank. Many moderate explosive eruptions have
been recorded since the mid-19th century.



Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
https://urldefense.com/v3/__http://www.phivolcs.dost.gov.ph/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCyjDhXmZ$ 
<https://urldefense.com/v3/__http://www.phivolcs.dost.gov.ph/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclfI5_6p4$>





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



PVMBG reported that the eruption at Dukono was ongoing during 10-16
January. Gray-and-white ash plumes generally rose 100-700 m above the
summit and drifted S during 10-15 January; emissions were not observed on
11 January. White-and-gray ash plumes rose to 1.7 km above the summit and
drifted SW on 16 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC2cxzImG$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclBrb4sSY$>





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
4-11 January. According to volcanologists in Severo-Kurilsk (Paramushir
Island, about 7 km E), explosions on 6, 8, and 9 January generated ash
plumes that rose as high as 2.5 km (8,200 ft) a.s.l and drifted SE and NW.
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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC4_vndU-$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclC4JlDFc$>





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



On 11 January AVO reported that a radar image of Great Sitkin showed that
the thick flow in the summit crater continued to expand to the E and
reached the N margin of an earlier flow; effusion likely continued during
12-16 January. Local webcams and seismic data communications were offline
due to a storm-related power failure. No unusual activity was visible in
mostly cloudy satellite images. Weakly elevated surface temperatures were
identified in satellite data during 15-16 January. 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC51AcWEy$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclxXPGcbQ$>





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



PVMBG reported that the eruption at Lewotolok continued during 10-16
January. White-and-gray ash plumes rose 150 m above the summit and drifted
E on 12 January. White steam-and-gas plumes rose as high as 200 m above the
summit and drifted NE, E, and SE on the other days, though no emissions
were visible on 12 January. 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC2cxzImG$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclBrb4sSY$>





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



BPPTKG reported that the eruption at Merapi (on Java) continued during 5-11
January. The SW lava dome produced a total of 189 lava avalanches that
descended the S, SW, and W flanks; eight traveled S as far as 1.5 km down
the upper part of the Boyong drainage, 178 traveled SW as far as 1.8 km
down the upper part of the Bebeng drainage, and three traveled as far as
1.5 km down the Sat/Putih drainage. Four pyroclastic flows descended the
Boyong and Bebeng drainages as far as 1.5 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCyJklUX2$ 
<https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclWctOiWk$>





Poas  | Costa Rica  | 10.2°N, 84.233°W  | Summit elev. 2697 m



OVSICORI-UNA reported that small phreatic eruptions at Poás continued to be
observed during 8-16 January. Phreatic eruptions were recorded daily,
ejecting sediment no more than 200 m above the lakeâ??s surface and producing
steam-and-gas plumes that rose no higher than 500 m. In a special report
OVSICORI-UNA noted that both gas-and-steam emissions and seismicity began
to increase during the second half of 2023. The lake level had been
decreasing since October 2023 and eruptive events became more frequent and
energetic in December; a phreatic eruption at 2051 on 11 January was the
largest event recorded during December 2023-January 2024.



Geologic Summary. The broad vegetated edifice of Poás, one of the most
active volcanoes of Costa Rica, contains three craters along a N-S line.
The frequently visited multi-hued summit crater lakes of the
basaltic-to-dacitic volcano are easily accessible by vehicle from the
nearby capital city of San José. A N-S-trending fissure cutting the complex
stratovolcano extends to the lower N flank, where it has produced the Congo
stratovolcano and several lake-filled maars. The southernmost of the two
summit crater lakes, Botos, last erupted about 7,500 years ago. The more
prominent geothermally heated northern lake, Laguna Caliente, is one of the
world's most acidic natural lakes, with a pH of near zero. It has been the
site of frequent phreatic and phreatomagmatic eruptions since an eruption
was reported in 1828. Eruptions often include geyser-like ejections of
crater-lake water.



Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad
Nacional (OVSICORI-UNA) https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCw4vHvkr$ 
<https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclasMfrF0$>





Popocatepetl  | Mexico  | 19.023°N, 98.622°W  | Summit elev. 5393 m



CENAPRED reported that eruptive activity continued at Popocatépetl during
9-16 January. Long-period events totaling 6-64 per day were accompanied by
steam-and-gas plumes that occasionally contained minor amounts of ash. The
plumes mainly drifted ENE and NE. The seismic network recorded 14.5-23
daily hours of tremor, including both low- and high-frequency events. Minor
amounts of ash fell in Nealtican (21 km E) during 11-12 January. Ashfall
was also reported in Nativitas (40 km NE), Tetlatlahuaca (42 km NE),
Zacatelco (45 km NE), Xicohtinco (45 km NE), Ayometla (46 km ENE),
Papalotla (62 km NNW), Tenancingo, San Pablo del Monte (49 km E),
Mazatecochco (50 km ENE), Tlaxcala (50 km NW), and Tepeyanco (47 km NW) in
the state of Tlaxcala on 15 January and in Nealtican, Juan C. Bonilla (32
km ENE), and Tlaltenango in the state of Puebla on 16 January. The Alert
Level remained at Yellow, Phase Two (the middle level on a three-color
scale) and the public was warned to stay 12 km away from the crater.



Geologic Summary. Volcán Popocatépetl, whose name is the Aztec word for
smoking mountain, rises 70 km SE of Mexico City to form North America's
2nd-highest volcano. The glacier-clad stratovolcano contains a
steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is
modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier
volcano. At least three previous major cones were destroyed by
gravitational failure during the Pleistocene, producing massive
debris-avalanche deposits covering broad areas to the south. The modern
volcano was constructed south of the late-Pleistocene to Holocene El Fraile
cone. Three major Plinian eruptions, the most recent of which took place
about 800 CE, have occurred since the mid-Holocene, accompanied by
pyroclastic flows and voluminous lahars that swept basins below the
volcano. Frequent historical eruptions, first recorded in Aztec codices,
have occurred since Pre-Columbian time.



Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
https://urldefense.com/v3/__https://www.gob.mx/cenapred__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC1AjyXDt$ 
<https://urldefense.com/v3/__https://www.gob.mx/cenapred__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclnJuVZh8$>





Rincon de la Vieja  | Costa Rica  | 10.83°N, 85.324°W  | Summit elev. 1916 m



OVSICORI-UNA reported continued unrest at Rincón de la Vieja during 8-16
January. Small phreatic eruptions were recorded almost daily, sometimes
producing gas-and-steam plumes that rose as high as 3 km above the crater
rim. Almost continuous gas-and-steam emissions were visible during 10-11
January. The Alert Level remained at Level 3, Orange, the third level on a
four-level scale.



Geologic Summary. Rincón de la Vieja, the largest volcano in NW Costa Rica,
is a remote volcanic complex in the Guanacaste Range. The volcano consists
of an elongated, arcuate NW-SE-trending ridge constructed within the
15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on
the south side. Sometimes known as the "Colossus of Guanacaste," it has an
estimated volume of 130 km3 and contains at least nine major eruptive
centers. Activity has migrated to the SE, where the youngest-looking
craters are located. The twin cone of Santa María volcano, the highest peak
of the complex, is located at the eastern end of a smaller, 5-km-wide
caldera and has a 500-m-wide crater. A Plinian eruption producing the 0.25
km3 Río Blanca tephra about 3,500 years ago was the last major magmatic
eruption. All subsequent eruptions, including numerous historical eruptions
possibly dating back to the 16th century, have been from the prominent
active crater containing a 500-m-wide acid lake located ENE of Von Seebach
crater.



Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad
Nacional (OVSICORI-UNA) https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCw4vHvkr$ 
<https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclasMfrF0$>





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



IG-EPN reported a high level of eruptive activity at Sangay during 9-16
January, with seismic stations recording 232-626 daily explosions.
Ash-and-gas plumes were visible in both webcam and satellite images during
9-14 January, rising as high as 1.5 km above the crater rim and drifting W,
WSW, and SW. On 12 January an explosion deposited incandescent material on
all flanks as far as 1 km from the summit crater. At 1810 that same day a
pyroclastic density current descended the SE drainage and an ash plume rose
1 km above the summit and drifted SW. Crater incandescence was sometimes
visible at night, and during 11-12 and 13-14 January incandescent material
was observed descending the SE drainage as far as 1 km. Cloudy weather
prevented views during 15-16 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCwENta0x$ 
<https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYcl395Gg0E$>
;

Secretaría de Gestión de Riesgos (SGR) https://urldefense.com/v3/__http://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC4c40-ef$ 
<https://urldefense.com/v3/__http://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclpatdkMI$>





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



PVMBG reported that eruptive activity continued at Semeru during 10-16
January. Daily white-and-gray ash plumes that were sometimes dense rose
500-1,000 m above the summit and drifted in multiple directions. 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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC2cxzImG$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclBrb4sSY$>





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



KVERT reported that the eruption at Sheveluch continued during 4-11 January
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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeC4_vndU-$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclC4JlDFc$>





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 8-15 January. Eruptive events on 11 January produced ash plumes that
rose as high as 1.1 km above the crater rim and drifted SE. An explosion at
0548 on 13 January produced an ash plume that rose 800 m and drifted SE. At
0022 on 14 January an explosion ejected large blocks 1.1 km to the N and 1
km to the S of the vent and produced an ash plume that rose 500 m above the
crater rim. The Alert Level was raised to 3 (on a 5-level scale) and the
public was warned to stay 2 km away from the crater. Another eruptive event
at 2313 on 15 January generated an ash plume that rose more than 1 km above
the crater rim and drifted S.



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!b3B2xxeg2V9UVxxgzzWVkVywk5vEBJ8oAl1Nva3SBX3SJeat4uYz3qmB-ifNlWpPa9b7tJKeCxsdlrmr$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!abuKWUt8iakaMY655meQ1E33PSNQF7r4ljOIwwQgvXi_ttI-rqx4vOTwR7aAYxMLRYclsXSNHqA$>


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End of Volcano Digest - 17 Jan 2024 to 19 Jan 2024 (#2024-6)
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