Smithsonian / USGS Weekly Volcanic Activity Report 19-25 April 2023

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


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


Smithsonian / USGS Weekly Volcanic Activity Report

19-25 April 2023



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

Zac Hastings - contributor (zhastings@xxxxxxxx)

JoAnna Marlow - contributor (jmarlow@xxxxxxxx)

URL: https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9ca28kVi$ 
<https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkr1-NGgM$>






New Activity/Unrest: Bezymianny, Central Kamchatka (Russia)  | Nevado del
Ruiz, Colombia  | Rincon de la Vieja, Costa Rica  | Sheveluch, Central
Kamchatka (Russia)



Ongoing Activity: Ahyi, Mariana Islands (USA)  | Aira, Kyushu (Japan)  |
Ambae, Vanuatu  | Cotopaxi, Ecuador  | Ebeko, Paramushir Island (Russia)  |
Fuego, South-Central Guatemala  | Great Sitkin, Andreanof Islands (USA)  |
Karangetang, Sangihe Islands  | Katmai, Alaska  | Lewotolok, Lembata
Island  | Merapi, Central Java  | Reventador, Ecuador  | Sabancaya, Peru  |
Santa Maria, Southwestern Guatemala  | Semeru, Eastern Java  |
Semisopochnoi, Aleutian Islands (USA)  | 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





Bezymianny  | Central Kamchatka (Russia)  | 55.972°N, 160.595°E  | Summit
elev. 2882 m



KVERT reported that a daily thermal anomaly from continuing lava effusion
at Bezymianny was identified in satellite images during 14-20 April.
Gas-and-steam emissions were visible and occasional collapses from the
growing lava dome produced avalanches of hot material. The Aviation Color
Code was lowered to Yellow (the second lowest level on a four-color scale)
on 20 April because activity had declined after the strong 7-8 April
explosive eruption. Dates are based on UTC times; specific events are in
local time where noted.



Geologic Summary. The modern Bezymianny, much smaller than its massive
neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed
about 4,700 years ago over a late-Pleistocene lava-dome complex and an
ancestral edifice built about 11,000-7,000 years ago. Three periods of
intensified activity have occurred during the past 3,000 years. The latest
period, which was preceded by a 1,000-year quiescence, began with the
dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in
1980, produced a large open crater that was formed by collapse of the
summit and an associated lateral blast. Subsequent episodic but ongoing
lava-dome growth, accompanied by intermittent explosive activity and
pyroclastic flows, has largely filled the 1956 crater.



Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9WUBfWdM$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk6_7GRow$>






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 the eruption at Nevado del Ruiz
continued during 18-25 April and was characterized by gas, steam, and ash
emissions, thermal anomalies at the lava dome in Arenas Crater, and
elevated seismicity. Seismic signals indicating rock-fracturing events were
located 1-3 km W, SW, NE, and E of Arenas Crater and below the crater, at
depths of 0.4-6.2 km. The largest event, a M 1.7, was recorded at 1735 on
24 April and was located 4.1 km E of the crater, at a depth of 3.2 km. The
event was felt by residents in the Lagunilla river canyon. Additionally,
signals indicating fluid movement fluctuated in intensity and were
associated with daily gas-and-steam emissions, sometimes containing ash,
that rose as high as 1.8 km above the crater rim. At 0711 on 18 April an
ash plume rose 1.8 km above the crater rim and drifted SE, causing ashfall
in the municipality of Anzoátegui, Tolima. At 2235 on 19 April and at 2248
on 21 April ash plumes rose 1.8 km and drifted SSE. Gas emissions with
possible ash rose as high as 1.3 km and drifted SW and E during 20-21
April. Pulsating ash emissions were seen in webcam images during 23-25
April. The Alert Level was remained at Orange, Level II (the second highest
level on a four-level scale).



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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9a6C7iaz$ 
<https://urldefense.com/v3/__https://www2.sgc.gov.co/volcanes/index.html__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkdTGNbRQ$>






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




OVSICORI-UNA reported that phreatic eruptions, detected seismically but
often with observed emissions, continued to occur at Rincón de la Vieja
during 18-25 April. Several eruptive events recorded during 18-21 April
produced gas-and-steam emissions that rose as high as 1.5 km above the
crater rim. A strong eruptive event at 1550 on 21 April generated a dense
plume of material that rose 500 m above the crater rim and then collapsed,
producing a pyroclastic flow and lahars on the N flank. A steam-and-gas
plume with minor ash content rose 4-5 km above the crater rim. Strong
tremor levels and near-continuous gas emissions were recorded after the
event. That same day OVSICORI-UNA noted that during the previous week
sulfur dioxide emissions were 221 tons per day on average, though emissions
spiked to close to 5,000 tons per day after several of the phreatic events.
During 22-24 April nearly continuous gas emissions continued to be visible
and strong tremor continued to be recorded by the seismic network. Small
phreatic events were recorded at 1904 on 22 April and at 0054 and 0629 on
24 April. Small phreatic events at 2250 on 23 April and 0630 on 24 April
produced steam-and-gas plumes that rose no higher than 500 m above the
crater rim.



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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9aJotmBf$ 
<https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk1W1XGHk$>






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



KVERT reported that a thermal anomaly over Sheveluch was identified in
satellite images during 14-20 April. During 14-15 April ash plumes rose to
6 km (19,700 ft) a.s.l. and drifted 700 km NW. During 17-19 April plumes of
unconsolidated ash resuspended from the flanks by wind rose to 4 km (13,100
ft) a.s.l. and drifted as far as 224 km NW. The sulfur dioxide gas portion
of the eruption cloud produced during the notable 11-12 April activity
continued to drift E; by 21 April the leading edge of the plume was over
part of Greenland. The Aviation Color Code remained at Orange (the second
highest 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9WUBfWdM$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk6_7GRow$>






Ongoing Activity





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



On 26 April both the Aviation Color Code and the Volcano Alert Level for
Ahyi Seamount were lowered to Unassigned because signs of unrest had
decreased, and no indication of submarine volcanic activity had occurred
for at least four weeks. Observations of discolored water near the seamount
were last identified in satellite images in late March 2023, and underwater
activity based on acoustic signals had been negligible since early April
2023.



Geologic Summary. Ahyi seamount is a large conical submarine volcano that
rises to within 75 m of the sea surface about 18 km SE of the island of
Farallon de Pajaros (Uracas) 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 of the seamount, 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9fgRZ10t$ 
<https://urldefense.com/v3/__https://www.usgs.gov/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkbcPZOVM$>






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



JMA reported ongoing eruptive activity at Minamidake Crater (at Aira
Calderaâ??s Sakurajima volcano) during 17-24 April, with crater incandescence
visible nightly. Two eruptive events on 17 April produced ash plumes that
rose 1-1.5 km and drifted S. That same day sulfur dioxide emissions were
somewhat high at 1,900 tons per day. Very small eruptive events
occasionally occurred during 21-24 April. The Alert Level remained at 3 (on
a 5-level scale), and residents were 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 Aira caldera,
along with several post-caldera cones. The construction of Sakurajima began
about 13,000 years ago on the southern rim of Aira caldera and built an
island that was finally joined to the Osumi Peninsula during the major
explosive and effusive eruption of 1914. Activity at the Kitadake summit
cone ended about 4850 years ago, after which eruptions took place at
Minamidake. Frequent historical eruptions, recorded since the 8th century,
have deposited ash on Kagoshima, one of Kyushu's largest cities, located
across Kagoshima Bay only 8 km from the summit. The largest historical
eruption took place during 1471-76.



Source: Japan Meteorological Agency (JMA) https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9SOk8ezD$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk8hHU4-U$>






Ambae  | Vanuatu  | 15.389°S, 167.835°E  | Summit elev. 1496 m



Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that at 0730
on 19 April a plume consisting of steam, sulfur dioxide gas, and ash rose
695 m above Ambaeâ??s summit and drifted E and SE, based on an image from a
webcam located 22 km NE on the NE tip of Ambae Island, in Saratamata. The
Alert Level remained at 2 (on a scale of 0-5) and the public was warned to
stay outside of the Danger Zone, defined as a 2-km radius around the active
vents in Lake Voui, and away from drainages during heavy rains.



Geologic Summary. The island of Ambae, also known as Aoba, is a massive
2,500 km3 basaltic shield that is the most voluminous volcano of the New
Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with
scoria cones gives the 16 x 38 km island an elongated form. A broad
pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and
Manaro Lakua) is located at the summit within the youngest of at least two
nested calderas, the largest of which is 6 km in diameter. That large
central edifice is also called Manaro Voui or Lombenben volcano.
Post-caldera explosive eruptions formed the summit craters about 360 years
ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years
later. The latest known flank eruption, about 300 years ago, destroyed the
population of the Nduindui area near the western coast.



Source: Vanuatu Meteorology and Geo-Hazards Department (VMGD)
https://urldefense.com/v3/__http://www.geohazards.gov.vu/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9VQ1dDtk$ 
<https://urldefense.com/v3/__http://www.geohazards.gov.vu/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkzgYN6xE$>






Cotopaxi  | Ecuador  | 0.677°S, 78.436°W  | Summit elev. 5911 m



IG reported ongoing moderate eruptive activity at Cotopaxi during 18-25
April. Cloudy weather sometimes prevented webcam and satellite views, but
daily emissions of steam-and-gas rising as high as 1.5 km were seen in
webcam images. Small ash-and-gas emissions were visible during 21-22 April.
An ash plume first seen at 0953 on 24 April rose up to 3 km above the
summit and drifted NE. Later that afternoon and evening ash-and-gas
emissions rose 350 m and drifted N. At 1600 the seismic station recorded a
small secondary lahar that descended the Cutzalao/Agualongo drainage on the
SW flank. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
maintained the Alert Level at Yellow (the second lowest level on a
four-color scale).



Geologic Summary. The symmetrical, glacier-covered, Cotopaxi stratovolcano
is Ecuador's most well-known volcano and one of its most active. The
steep-sided cone is capped by nested summit craters, the largest of which
is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate
from the summit of the andesitic volcano, and large andesitic lava flows
extend to its base. The modern edifice has been constructed since a major
collapse sometime prior to about 5,000 years ago. Pyroclastic flows (often
confused in historical accounts with lava flows) have accompanied many
explosive eruptions, and lahars have frequently devastated adjacent
valleys. Strong eruptions took place in 1744, 1768, and 1877. Pyroclastic
flows descended all sides of the volcano in 1877, and lahars traveled more
than 100 km into the Pacific Ocean and western Amazon basin. Smaller
eruptions have been frequent since that time.



Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9RhLQAsC$ 
<https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkDxH06l8$>
;

Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9X3k-Vkr$ 
<https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk351RJTs$>






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



KVERT reported that moderate activity at Ebeko was ongoing during 13-20
April and a thermal anomaly was identified in satellite images during 14-15
April. According to volcanologists in Severo-Kurilsk (Paramushir Island,
about 7 km E), and satellite data, explosions during 14-16 April generated
ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted 104
km NE. Weather clouds prevented satellite views on the other days of the
week. The Aviation Color Code remained at Orange (the second highest level
on a four-color scale). Dates are based on UTC times; 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9WUBfWdM$ 
<https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk6_7GRow$>






Fuego  | South-Central Guatemala  | 14.473°N, 90.88°W  | Summit elev. 3763 m




INSIVUMEH reported that 4-12 explosions per hour were recorded at Fuego
during 18-25 April, generating daily ash plumes that rose as high as 1 km
above the crater rim and drifted as far as 65 km SW, S, SE, and E. Ashfall
was recorded each day in areas downwind including Morelia (9 km SW),
Panimaché I and II (8 km SW), La Rochela, Santa Sofía (12 km SW), San
Andrés Osuna, Ceilan, Finca La Asunción, Ceylon, El Zapote (10 km S),
Aldeas, El Rodeo and other nearby communities. Daily block avalanches
descended multiple drainages including the Santa Teresa, Ceniza (SSW), Seca
(W), Trinidad (S), Taniluyá (SW), Honda, Las Lajas (SE), and El Jute (ESE),
and often reached vegetated areas. Daily shock waves rattled structures in
communities around the volcano and rumbling was often heard. Explosions
ejected incandescent material as high as 350 m above the summit on most
days. During 22-23 April the avalanches remobilized ash deposits causing a
plume that rose 100 m and drifted S and SE. On 23 April lahars in the
Ceniza drainage carried branches, tree trunks, and blocks 30 cm to 1.5 m in
diameter.



Geologic Summary. Volcán Fuego, one of Central America's most active
volcanoes, is also one of three large stratovolcanoes overlooking
Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta,
lies between Fuego and Acatenango to the north. Construction of Meseta
dates back to about 230,000 years and continued until the late Pleistocene
or early Holocene. Collapse of Meseta may have produced the massive
Escuintla debris-avalanche deposit, which extends about 50 km onto the
Pacific coastal plain. Growth of the modern Fuego volcano followed,
continuing the southward migration of volcanism that began at the mostly
andesitic Acatenango. Eruptions at Fuego have become more mafic with time,
and most historical activity has produced basaltic rocks. Frequent vigorous
historical eruptions have been recorded since the onset of the Spanish era
in 1524, and have produced major ashfalls, along with occasional
pyroclastic flows and lava flows.



Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9R5kY4CA$ 
<https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkUCjdA3M$>






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



AVO reported that lava continued to slowly erupt at the summit of Great
Sitkin during 19-25 April. Weather clouds often obscured satellite and
webcam views during most of the week. Seismicity was low, and during 21-22
April only a few small events were detected. Satellite data last acquired
on 14 April showed that the thick lava continued to expand towards the E
and remained confined to the summit crater. The Volcano Alert Level
remained at Watch (the second highest level on a four-level scale) and the
Aviation Color Code remained at Orange (the second highest level on a
four-color scale).



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



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9Vner6kM$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk5zUz8xE$>






Karangetang  | Sangihe Islands  | 2.781°N, 125.407°E  | Summit elev. 1797 m



PVMBG reported that the effusive eruption which began around 1700 on 8
February at Karangetangâ??s Main Crater (S crater) produced lava flows and
lava avalanches that traveled as far as 2 km down the SW and S flanks in
drainages leading to the Beha, Batang, Timbelang, Batuawang, and Kahetang
rivers. Effusion ended on 1 April and avalanches of material were no longer
detected. Seismic signals indicating effusion decreased and by 6 April were
no longer being detected. Incandescence at both Main Crater and Crater II
(N crater) was visible at night during 1-25 April. White gas plumes were
seen rising as high as 200 m above the summit and drifted in multiple
directions; weather clouds sometimes prevented views. On 26 April the Alert
Level was lowered to 2 (on a scale of 1-4) and the public was warned to
stay 2.5 km away from the craters on the S and SW flanks and 1.5 km away on
the other flanks.



Geologic Summary. Karangetang (Api Siau) volcano lies at the northern end
of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi.
The stratovolcano contains five summit craters along a N-S line. It is one
of Indonesia's most active volcanoes, with more than 40 eruptions recorded
since 1675 and many additional small eruptions that were not documented
(Neumann van Padang, 1951). Twentieth-century eruptions have included
frequent explosive activity sometimes accompanied by pyroclastic flows and
lahars. Lava dome growth has occurred in the summit craters; collapse of
lava flow fronts have produced pyroclastic flows.



Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9QnWiod_$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkawMaeHU$>






Katmai  | Alaska  | 58.28°N, 154.963°W  | Summit elev. 2047 m



AVO reported that during the morning of 23 April, strong NW winds in the
vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed
unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the SE across Shelikof
Strait to Kodiak Island. The ash was originally deposited during the
Novarupta-Katmai eruption in 1912. The Volcano Alert Level remained at
Normal (the lowest level on a four-level scale) and the Aviation Color Code
remained at Green (the lowest level on a four-color scale).



Geologic Summary. Katmai was initially considered to be the source of the
Valley of Ten Thousand Smokes ash flow in 1912. However, the 3 x 4 km
caldera of 1912 is now known to have formed as a result of the voluminous
eruption at nearby Novarupta volcano. Prior to 1912 this compound
stratovolcano had four NE-SW-trending summits, most of which were truncated
by caldera collapse in that year. Two or more large explosive eruptions
took place during the late Pleistocene. Most of the two overlapping
pre-1912 Katmai volcanoes are Pleistocene, but Holocene lava flows from a
flank vent descend the SE flank of the SW edifice into the Katmai River
canyon. The steep walled young caldera has a jagged rim that rises
500-1,000 m above the caldera floor and contains a 250-m-deep, still-rising
lake. Lake waters have covered a small post-collapse lava dome (Horseshoe
Island) that was seen on the caldera floor at the time of the initial
ascent to the caldera rim in 1916.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9Vner6kM$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk5zUz8xE$>






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



PVMBG reported that the eruption at Lewotolok was ongoing during 19-25
April. On 19, 21, and 23 April white-and-gray plumes rose 200-700 m and
drifted E, NE, N, and NW. White steam-and-gas plumes of variable densities
were seen during 20, 22, and 24-25 April rising as high as 500 m above the
summit and drifting SW, W, and NW. Crater incandescence was visible in
webcam images posted with the reports during 21-22 April. The Alert Level
remained at 2 (on a scale of 1-4) and the public was warned to stay 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9QnWiod_$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkawMaeHU$>






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



BPPTKG reported that the eruption at Merapi (on Java) continued during
19-25 April and seismicity remained at high levels. The SW lava dome
produced more than 80 lava avalanches that traveled as far as 2 km down the
SW flank (upstream in the Bebeng and Boyong drainages). Morphological
changes to the SW lava dome were evident in webcam images 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9T0yPKX9$ 
<https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkyK9IK8M$>






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



IG reported that the eruption at Reventador was ongoing during 19-25 April.
Seismic activity was not characterized due to technical problems. Steam,
gas, and ash plumes were observed in IG webcam images and described in
Washington VAAC advisories on most days; weather conditions occasionally
prevented views. The plumes rose as high as 1.6 km above the summit and
drifted E, SE, W, and SW. Crater incandescence was visible at night during
20-21 April. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
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 about 1,300 m 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 constructed a debris
plain on the eastern floor of the scarp. 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)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9RhLQAsC$ 
<https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkDxH06l8$>
;

Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)
https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9X3k-Vkr$ 
<https://urldefense.com/v3/__https://www.gestionderiesgos.gob.ec/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk351RJTs$>






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



Instituto Geofísico del Perú (IGP) reported moderate levels of activity at
Sabancaya during 17-23 April with a daily average of 31 explosions.
Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted NW,
W, SW, and S. Six thermal anomalies originating from the lava dome in the
summit crater were identified in satellite data. The Alert Level remained
at Orange (the second highest 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9StHWH4u$ 
<https://urldefense.com/v3/__http://www.igp.gob.pe/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk5a1DVj8$>






Santa Maria  | Southwestern Guatemala  | 14.757°N, 91.552°W  | Summit elev.
3745 m



INSIVUMEH reported that the eruption at Santa Maríaâ??s Santiaguito lava-dome
complex continued during 18-25 April. Effusion from the Caliente dome
complex fed lava flows that descended the San Isidro and Zanjón Seco
drainages on the W and SW flanks; the main lava flow was 4.3 km long and
remained active. Incandescence from the dome and the lava flows was
frequently visible at night. Daily avalanches descended multiple flanks of
the dome and were also occasionally generated from the lava-flow front and
margins. Daily weak or weak-to-moderate explosions recorded by the seismic
network generated ash plumes that rose as high as 1 km above the complex
and drifted mainly S and SW. During 18-19 April ash fall was reported in
Finca El Faro (6.7 km S). On 21 April quiet rumbling sounds were barely
heard on nearby farms. Residents were reminded to stay away from the lava
flow and at least 6 km away from the dome complex.



Geologic Summary. Symmetrical, forest-covered Santa María volcano is part
of a chain of large stratovolcanoes that rise above the Pacific coastal
plain of Guatemala. The sharp-topped, conical profile is cut on the SW
flank by a 1.5-km-wide crater. The oval-shaped crater extends from just
below the summit to the lower flank, and was formed during a catastrophic
eruption in 1902. The renowned Plinian eruption of 1902 that devastated
much of SW Guatemala followed a long repose period after construction of
the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito
lava-dome complex has been growing at the base of the 1902 crater since
1922. Compound dome growth at Santiaguito has occurred episodically from
four vents, with activity progressing W towards the most recent, Caliente.
Dome growth has been accompanied by almost continuous minor explosions,
with periodic lava extrusion, larger explosions, pyroclastic flows, and
lahars.



Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9R5kY4CA$ 
<https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkUCjdA3M$>






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



PVMBG reported that the eruption at Semeru continued during 18-25 April and
frequent Volcano Observatory Notices for Aviation (VONAs) describing ash
emissions were issued through the week. On 19 April at 0710 and 0829 dense
white-and-gray ash plumes rose 800-1,000 m above the summit and drifted S.
On 20 April at 0616, 0619, 0805, and 0902 white-and-gray variable density
ash plumes rose 300-1,000 m and drifted N and NW. At 0534 on 21 April a
white-to-brown ash plume rose 600 m and drifted NE and at 0640 a dense
white-and-gray ash plume rose 700 m and drifted SW. On 23 April at 0448,
0553, 0643, and 0731 gray ash plumes of variable densities rose 400-1,000 m
and drifted SE, S, SW, and W. On 25 April at 0519, 0710, and 0756 dense
gray ash plumes rose 500-800 m and drifted NW, W, and SW. The Alert Level
remained at 3 (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,
100 m from the banks of the Kobokan drainage as far as 17 km from the
summit, and to avoid other drainages originating on Semeru, 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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9QnWiod_$ 
<https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmkawMaeHU$>






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



AVO reported that low-level unrest continued at Semisopochnoi during 18-25
April. Daily periods or bursts of tremor and occasional low-frequency
earthquakes were detected during the week. Small explosions were detected
in seismic and infrasound data during 18-19 and 24-25 April. Cloudy weather
prevented webcam and satellite views on most days. Possible recent ash
deposits on Mount Youngâ??s crater rim were visible in clear webcam images
during 22-23 April, and steam emissions from the active N crater were
visible during 22-25 April. The Volcano Alert Level remained at Watch (the
second highest level on a four-level scale) and the Aviation Color Code
remained at Orange (the second highest color on a four-color scale).



Geologic Summary. Semisopochnoi, the largest subaerial volcano of the
western Aleutians, is 20 km wide at sea level and contains an 8-km-wide
caldera. It formed as a result of collapse of a low-angle, dominantly
basaltic volcano following the eruption of a large volume of dacitic
pumice. The high point of the island is Anvil Peak, a double-peaked
late-Pleistocene cone that forms much of the island's northern part. The
three-peaked Mount Cerberus (renamed Mount Young in 2023) was constructed
within the caldera during the Holocene. Each of the peaks contains a summit
crater; lava flows on the N flank appear younger than those on the south
side. Other post-caldera volcanoes include the symmetrical Sugarloaf Peak
SSE of the caldera and Lakeshore Cone, a small cinder cone at the edge of
Fenner Lake in the NE part of the caldera. Most documented eruptions have
originated from Young, although Coats (1950) considered that both Sugarloaf
and Lakeshore Cone could have been recently active.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9Vner6kM$ 
<https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk5zUz8xE$>






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 17-24 April. No explosions were recorded, but eruptive activity
produced periodic ash plumes and ejected blocks as far as 300 m from the
vent. On 17 April ash plumes rose 1-1.5 km above the crater rim and drifted
E and SE, and on 18 April an ash plume rose 2 km and drifted N. Ashfall was
reported in Toshima village (3.5 km SSW) during 17-21 April. On 23 April an
ash plume rose 1.1 km and drifted SW. The Alert Level remained at 3 (on a
5-level scale) and residents were warned to stay 2 km away from the crater.



Geologic Summary. The 8-km-long island of Suwanosejima in the northern
Ryukyu Islands consists of an andesitic stratovolcano with two historically
active summit craters. The summit is truncated by a large breached crater
extending to the sea on the east flank that was formed by edifice collapse.
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
blanketed residential areas, and the SW crater produced two lava flows that
reached the western coast. At the end of the eruption the summit of Otake
collapsed, forming a large debris avalanche and creating the open Sakuchi
caldera, which extends to the eastern coast. The island remained
uninhabited for about 70 years after the 1813-1814 eruption. Lava flows
reached the eastern coast of the island in 1884. Only about 50 people live
on the island.



Source: Japan Meteorological Agency (JMA) https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9SOk8ezD$ 
<https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!aorMFsDUwbXHLpdej360-BNwgNPDdUEW16W3y7NHqnZQkauO9JsWfKQdCLVmAJJZXgmk8hHU4-U$>



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



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



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!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9diPoc2n$ 

GVP - https://urldefense.com/v3/__http://www.volcano.si.edu/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9VdCCMsM$ 

IAVCEI - https://urldefense.com/v3/__https://www.iavceivolcano.org/__;!!IKRxdwAv5BmarQ!YU8oejYMj2KajBGuT5UXU8BWlhemURPIR2CBiNZbrBp0jCJcCRwSS3P65n5vbP04-yemBv_-9de2GbIA$ 



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End of Volcano Digest - 24 Apr 2023 to 26 Apr 2023 (#2023-46)
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