Smithsonian / USGS Weekly Volcanic Activity Report 18-24 March 2020

[Rachel Holsteen-Bruyere <rbruyere@xxxxxxx>]

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


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


Smithsonian / USGS Weekly Volcanic Activity Report

18-24 March 2020



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

URL: https://volcano.si.edu/reports_weekly.cfm





New Activity/Unrest: Manam, Papua New Guinea  | Soputan, Sulawesi
(Indonesia)



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Fuego, Guatemala  | Ibu, Halmahera
(Indonesia)  | Klyuchevskoy, Central Kamchatka (Russia)  | Krakatau,
Indonesia  | Nevado del Ruiz, Colombia  | Pacaya, Guatemala  |
Popocatepetl, Mexico  | Reventador, Ecuador  | Santa Maria, Guatemala  |
Semisopochnoi, United States  | Sheveluch, Central Kamchatka (Russia)  |
Shishaldin, Fox 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





Manam  | Papua New Guinea  | 4.08°S, 145.037°E  | Summit elev. 1807 m



The Darwin VAAC reported that during 20-21 March ash plumes from Manam rose
to an altitude of 3 km (10,000 ft) a.s.l. and drifted E, based on satellite
data and weather models.



Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the
northern coast of mainland Papua New Guinea, is one of the country's most
active volcanoes. Four large radial valleys extend from the unvegetated
summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its
lower flanks. These "avalanche valleys" channel lava flows and pyroclastic
avalanches that have sometimes reached the coast. Five small satellitic
centers are located near the island's shoreline on the northern, southern,
and western sides. Two summit craters are present; both are active,
although most historical eruptions have originated from the southern
crater, concentrating eruptive products during much of the past century
into the SE valley. Frequent historical eruptions, typically of
mild-to-moderate scale, have been recorded since 1616. Occasional larger
eruptions have produced pyroclastic flows and lava flows that reached
flat-lying coastal areas and entered the sea, sometimes impacting populated
areas.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





Soputan  | Sulawesi (Indonesia)  | 1.112°N, 124.737°E  | Summit elev. 1785 m



The Darwin VAAC reported that on 23 March an ash plume from Soputan was
seen by a pilot rising to an altitude of 4.3 km (14,000 ft) a.s.l.



Geologic Summary. The Soputan stratovolcano on the southern rim of the
Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of
Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano
is located SW of Riendengan-Sempu, which some workers have included with
Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was
constructed at the southern end of a SSW-NNE trending line of vents. During
historical time the locus of eruptions has included both the summit crater
and Aeseput, a prominent NE-flank vent that formed in 1906 and was the
source of intermittent major lava flows until 1924.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





Ongoing Activity





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



JMA reported that during 16-23 March incandescence from Minamidake Crater
(at Aira Calderaâ??s Sakurajima volcano) was visible nightly. Occasional
eruptive events were recorded along with seven explosions. Ash plumes rose
2.8-3 km above the crater rim and material was ejected 1.1-1.7 km away from
the crater. The Alert Level remained at 2 (on a 5-level scale).



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



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





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



Based on satellite and wind model data, the Darwin VAAC reported that
during 18-24 March ash plumes from Dukono rose to 1.5-2.3 km (5,000-8,000
ft) a.s.l. and drifted in multiple directions. The Alert Level remained at
2 (on a scale of 1-4), and the public was warned to remain outside of the
2-km exclusion zone.



Geologic Summary. Reports from this remote volcano in northernmost
Halmahera are rare, but Dukono has been one of Indonesia's most active
volcanoes. More-or-less continuous explosive eruptions, sometimes
accompanied by lava flows, occurred from 1933 until at least the mid-1990s,
when routine observations were curtailed. During a major eruption in 1550,
a lava flow filled in the strait between Halmahera and the north-flank cone
of Gunung Mamuya. This complex volcano presents a broad, low profile with
multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of
the summit crater complex, contains a 700 x 570 m crater that has also been
active during historical time.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





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



Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of
Ebeko, observed bursts of gas, steam, and a small amount of ash that rose
up to 2.5 km (8,200 ft) a.s.l. on 13 and 17 March. Ash plumes drifted NE
and SE. The Aviation Color Code remained at Orange (the second highest
level on a four-color scale).



Geologic Summary. The flat-topped summit of the central cone of Ebeko
volcano, one of the most active in the Kuril Islands, occupies the northern
end of Paramushir Island. Three summit craters located along a SSW-NNE line
form Ebeko volcano proper, at the northern end of a complex of five
volcanic cones. Blocky lava flows extend west from Ebeko and SE from the
neighboring Nezametnyi cone. The eastern part of the southern crater
contains strong solfataras and a large boiling spring. The central crater
is filled by a lake about 20 m deep whose shores are lined with steaming
solfataras; the northern crater lies across a narrow, low barrier from the
central crater and contains a small, cold crescentic lake. Historical
activity, recorded since the late-18th century, has been restricted to
small-to-moderate explosive eruptions from the summit craters. Intense
fumarolic activity occurs in the summit craters, on the outer flanks of the
cone, and in lateral explosion craters.



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





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



On 16 March INSIVUMEH reported an increased number of avalanches at Fuego,
traveling down the Ceniza (SSW), Trinidad (S), and Las Lajas (SE) ravines.
A 600-m-long lava flow advanced down the Trinidad drainage. Weak explosive
activity accompanied lava effusion. There were 4-12 explosions per hour
recorded at Fuego during 17-24 March, generating ash plumes that rose as
high as 1.1 km above the crater rim and generally drifted 10-22 km S, SW,
and W. Almost daily ashfall was reported in several areas downwind
including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8
km SW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), Sangre de Cristo (8
km WSW), El Porvenir (8 km ENE), and La Cruz. Explosions sometimes produced
shock waves that rattled nearby houses and were felt in communities within
a 25-km radius. Incandescent material was ejected 100-400 m high and caused
avalanches of material that occasionally traveled long distances (reaching
vegetated areas) down the Seca (W), Taniluyá (SW), Ceniza, Trinidad, Honda,
and Las Lajas ravines. Lava flows of variable lengths (400-1,000 m)
descended the Trinidad and Ceniza ravines each day but were inactive by the
evening of 23 March.



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) http://www.insivumeh.gob.gt/





Ibu  | Halmahera (Indonesia)  | 1.488°N, 127.63°E  | Summit elev. 1325 m



The Darwin VAAC reported that during 18-19 March ash plumes from Ibu rose
to 2.1 km (7,000 ft) a.s.l. and drifted W based on satellite images and
weather models. 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 active crater, and
3.5 km away on the N side.



Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along
the NW coast of Halmahera Island has large nested summit craters. The inner
crater, 1 km wide and 400 m deep, contained several small crater lakes
through much of historical time. The outer crater, 1.2 km wide, is breached
on the north side, creating a steep-walled valley. A large parasitic cone
is located ENE of the summit. A smaller one to the WSW has fed a lava flow
down the W flank. A group of maars is located below the N and W flanks.
Only a few eruptions have been recorded in historical time, the first a
small explosive eruption from the summit crater in 1911. An eruption
producing a lava dome that eventually covered much of the floor of the
inner summit crater began in December 1998.



Sources: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml;

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





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



KVERT reported that Strombolian activity at Klyuchevskoy was visible during
13-20 March, and the number of hot avalanches descending all of the flanks
continued to increase. A bright thermal anomaly was identified daily in
satellite images. Gas-and-steam plumes containing some ash drifted as far
as 170 km E, NE, and N at altitudes of 5.5-6.5 km (18,000-21,300 ft) a.s.l.
during 15 and 18-19 March. Vulcanian activity was visible on 19 March. The
Aviation Color Code remained at Orange.



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



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





Krakatau  | Indonesia  | 6.102°S, 105.423°E  | Summit elev. 155 m



PVMBG reported that on 18 March a dense white-gray plume rose 300 m above
the summit of Anak Krakatau and drifted S. The event lasted just over 10
minutes based on seismic data. The Alert Level remained at 2 (on a scale of
1-4), and the public was warned to remain outside of the 2-km-radius hazard
zone from the crater.



Geologic Summary. The renowned volcano Krakatau (frequently misstated as
Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of
the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a
7-km-wide caldera. Remnants of this ancestral volcano are preserved in
Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan
volcanoes were formed, coalescing to create the pre-1883 Krakatau Island.
Caldera collapse during the catastrophic 1883 eruption destroyed Danan and
Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd
largest in Indonesia during historical time, caused more than 36,000
fatalities, most as a result of devastating tsunamis that swept the
adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km
across the Sunda Strait and reached the Sumatra coast. After a quiescence
of less than a half century, the post-collapse cone of Anak Krakatau (Child
of Krakatau) was constructed within the 1883 caldera at a point between the
former cones of Danan and Perbuwatan. Anak Krakatau has been the site of
frequent eruptions since 1927.



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





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 small and periodic ash-and-gas
emissions from Nevado del Ruiz were visible in satellite and webcam images
during 18-24 March. These emissions drifted NE and SE. A gas-and-steam
plume rose 1.5 km above the crater rim on 23 March. The Alert Level
remained at 3 (Yellow; the second lowest level on a four-color 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://www2.sgc.gov.co/volcanes/index.html





Pacaya  | Guatemala  | 14.382°N, 90.601°W  | Summit elev. 2569 m



INSIVUMEH reported that during 17-24 March Strombolian explosions at
Pacayaâ??s Mackenney Crater ejected material as high as 100 m above the
crater rim. Multiple lava flows (as many as four per day) traveled 100-300
m NW, W, and SW flanks.



Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active
volcanoes, are frequently visible from Guatemala City, the nation's
capital. This complex basaltic volcano was constructed just outside the
southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A
cluster of dacitic lava domes occupies the southern caldera floor. The
post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro
Grande stratovolcanoes and the currently active Mackenney stratovolcano.
Collapse of Pacaya Viejo between 600 and 1500 years ago produced a
debris-avalanche deposit that extends 25 km onto the Pacific coastal plain
and left an arcuate somma rim inside which the modern Pacaya volcano
(Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on
the NW somma rim and was last active in the 19th century. During the past
several decades, activity has consisted of frequent strombolian eruptions
with intermittent lava flow extrusion that has partially filled in the
caldera moat and armored the flanks of Mackenney cone, punctuated by
occasional larger explosive eruptions that partially destroy the summit of
the growing young stratovolcano.



Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/





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



CENAPRED reported that each day during 17-23 March there were 74-182
steam-and-gas emissions from Popocatépetl, some of which contained minor
amounts of ash. An explosion at 2210 on 17 March ejected incandescent
material onto the flanks and produced an ash plume that rose 1.2 km above
the crater rim and drifted SE. Minor ashfall was reported in the
municipalities of Tetela del Volcán (20 km SW), San Andrés and Hueyapan (16
km SW), and Ocuituco (24 km SW) during 17-18 March. Some emissions were
accompanied by incandescent material ejected out of the crater between
2229-2315 on 18 March. An explosion at 1928 on 19 March ejected
incandescent material a short distance from the crater. On 22 March an ash
plume rose 1 km and drifted S and ejected incandescent tephra fell onto the
flanks at a distance of 800 m from the crater. The Alert Level remained at
Yellow, Phase Two (middle level on a three-color scale).



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://www.gob.mx/cenapred





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



IG reported that during 17-24 March seismic data from Reventadorâ??s network
indicated a high level of seismic activity, including explosions,
long-period earthquakes, and signals indicating emissions. Gas-and-ash
emissions were observed almost daily, though cloudy weather often prevented
views of the volcano; IG and the Washington VAAC reported gas-and-ash
emissions rising around 500-900 m above the crater rim, and as high as 2
km, and drifting NE, SE, S, and W. Ashfall was reported in San Rafael (8 km
ESE) on 17 March. Incandescent blocks rolled 900 m down the S and SE flanks
during 23-24 March.



Geologic Summary. 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 Volcán El Reventador
stratovolcano rises to 3562 m above the jungles of the western Amazon
basin. A 4-km-wide caldera widely breached to the east was formed by
edifice collapse and is partially filled by a young, unvegetated
stratovolcano that rises about 1300 m above the caldera floor to a height
comparable to the caldera rim. It has been the source of numerous lava
flows as well as explosive eruptions that were visible from Quito in
historical time. Frequent lahars in this region of heavy rainfall have
constructed a debris plain on the eastern floor of the caldera. The largest
historical 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.



Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
http://www.igepn.edu.ec/





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



INSIVUMEH reported that explosions at Santa María's Santiaguito lava-dome
complex generated ash plumes that rose 500-900 m above the crater and
drifted as far as 1 km NW, W, and SW. Avalanches of blocks descended the
SE, E, S, and SW flanks of Caliente cone.



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) http://www.insivumeh.gob.gt/





Semisopochnoi  | United States  | 51.93°N, 179.58°E  | Summit elev. 1221 m



AVO reported that activity at Semisopochnoi had decreased compared to the
previous week. Seismicity remained elevated during 19-24 March and no
surface activity was observed on most days, though weather clouds often
prevented visual confirmation. A steam plume was visible in a satellite
image on 21 March and weakly elevated surface temperatures were identified
in one satellite image during 21-22 March. The Aviation Color Code remained
at Orange and the Volcano Alert Level remained at Watch.



Geologic Summary. Semisopochnoi, the largest subaerial volcano of the
western Aleutians, is 20 km wide at sea level and contains an 8-km-wide
caldera. It formed as a result of collapse of a low-angle, dominantly
basaltic volcano following the eruption of a large volume of dacitic
pumice. The high point of the island is 1221-m-high Anvil Peak, a
double-peaked late-Pleistocene cone that forms much of the island's
northern part. The three-peaked 774-m-high Mount Cerberus volcano was
constructed during the Holocene within the caldera. Each of the peaks
contains a summit crater; lava flows on the northern flank of Cerberus
appear younger than those on the southern side. Other post-caldera
volcanoes include the symmetrical 855-m-high 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 historical eruptions have
originated from Cerberus, although Coats (1950) considered that both
Sugarloaf and Lakeshore Cone within the caldera could have been active
during historical time.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://avo.alaska.edu/





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 13-20 March. The Aviation Color Code remained at
Orange (the second highest level on a four-color scale).



Geologic Summary. The high, isolated massif of Sheveluch volcano (also
spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya
volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most
active volcanic structures. The summit of roughly 65,000-year-old Stary
Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera
breached to the south. Many lava domes dot its outer flanks. The Molodoy
Shiveluch lava dome complex was constructed during the Holocene within the
large horseshoe-shaped caldera; Holocene lava dome extrusion also took
place on the flanks of Stary Shiveluch. At least 60 large eruptions have
occurred during the Holocene, making it the most vigorous andesitic volcano
of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions
have provided valuable time markers for dating volcanic events in
Kamchatka. Frequent collapses of dome complexes, most recently in 1964,
have produced debris avalanches whose deposits cover much of the floor of
the breached caldera.



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





Shishaldin  | Fox Islands (USA)  | 54.756°N, 163.97°W  | Summit elev. 2857 m



AVO reported that seismicity at Shishaldin was characterized as
near-continuous tremor during 18-20 March and continuous tremor during
21-24 March. Steam-and-gas plumes rising from the summit crater were
recorded daily by the webcam and sometimes identified in satellite images.
Elevated surface temperatures, consistent with lava in the summit crater,
were also identified in satellite images. The Volcano Alert Level remained
at Watch and the Aviation Color Code remained at Orange.



Geologic Summary. The beautifully symmetrical Shishaldin is the highest and
one of the most active volcanoes of the Aleutian Islands. The
glacier-covered volcano is the westernmost of three large stratovolcanoes
along an E-W line in the eastern half of Unimak Island. The Aleuts named
the volcano Sisquk, meaning "mountain which points the way when I am lost."
A steam plume often rises from its small summit crater. Constructed atop an
older glacially dissected volcano, it is largely basaltic in composition.
Remnants of an older ancestral volcano are exposed on the W and NE sides at
1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its
NW flank, which is blanketed by massive aa lava flows. Frequent explosive
activity, primarily consisting of Strombolian ash eruptions from the small
summit crater, but sometimes producing lava flows, has been recorded since
the 18th century.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://avo.alaska.edu/





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



JMA reported that during 13-19 March incandescence from Suwanosejimaâ??s
Ontake Crater was visible nightly. On 14 March an ash plume rose 400 m
above the crater rim. On 23 March the Tokyo VAAC reported that an explosion
produced an ash plume that rose to an altitude of 0.9 km (3,000 ft) a.s.l.,
or 120 m above the summit, and drifted SE. The Alert Level remained at 2
(on a 5-level scale).



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



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

Tokyo Volcanic Ash Advisory Center (VAAC)
http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html

 Smithsonian / USGS Weekly Volcanic Activity Report

18-24 March 2020



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

URL: https://volcano.si.edu/reports_weekly.cfm





New Activity/Unrest: Manam, Papua New Guinea  | Soputan, Sulawesi
(Indonesia)



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Fuego, Guatemala  | Ibu, Halmahera
(Indonesia)  | Klyuchevskoy, Central Kamchatka (Russia)  | Krakatau,
Indonesia  | Nevado del Ruiz, Colombia  | Pacaya, Guatemala  |
Popocatepetl, Mexico  | Reventador, Ecuador  | Santa Maria, Guatemala  |
Semisopochnoi, United States  | Sheveluch, Central Kamchatka (Russia)  |
Shishaldin, Fox 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





Manam  | Papua New Guinea  | 4.08°S, 145.037°E  | Summit elev. 1807 m



The Darwin VAAC reported that during 20-21 March ash plumes from Manam rose
to an altitude of 3 km (10,000 ft) a.s.l. and drifted E, based on satellite
data and weather models.



Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the
northern coast of mainland Papua New Guinea, is one of the country's most
active volcanoes. Four large radial valleys extend from the unvegetated
summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its
lower flanks. These "avalanche valleys" channel lava flows and pyroclastic
avalanches that have sometimes reached the coast. Five small satellitic
centers are located near the island's shoreline on the northern, southern,
and western sides. Two summit craters are present; both are active,
although most historical eruptions have originated from the southern
crater, concentrating eruptive products during much of the past century
into the SE valley. Frequent historical eruptions, typically of
mild-to-moderate scale, have been recorded since 1616. Occasional larger
eruptions have produced pyroclastic flows and lava flows that reached
flat-lying coastal areas and entered the sea, sometimes impacting populated
areas.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





Soputan  | Sulawesi (Indonesia)  | 1.112°N, 124.737°E  | Summit elev. 1785 m



The Darwin VAAC reported that on 23 March an ash plume from Soputan was
seen by a pilot rising to an altitude of 4.3 km (14,000 ft) a.s.l.



Geologic Summary. The Soputan stratovolcano on the southern rim of the
Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of
Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano
is located SW of Riendengan-Sempu, which some workers have included with
Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was
constructed at the southern end of a SSW-NNE trending line of vents. During
historical time the locus of eruptions has included both the summit crater
and Aeseput, a prominent NE-flank vent that formed in 1906 and was the
source of intermittent major lava flows until 1924.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





Ongoing Activity





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



JMA reported that during 16-23 March incandescence from Minamidake Crater
(at Aira Calderaâ??s Sakurajima volcano) was visible nightly. Occasional
eruptive events were recorded along with seven explosions. Ash plumes rose
2.8-3 km above the crater rim and material was ejected 1.1-1.7 km away from
the crater. The Alert Level remained at 2 (on a 5-level scale).



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



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





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



Based on satellite and wind model data, the Darwin VAAC reported that
during 18-24 March ash plumes from Dukono rose to 1.5-2.3 km (5,000-8,000
ft) a.s.l. and drifted in multiple directions. The Alert Level remained at
2 (on a scale of 1-4), and the public was warned to remain outside of the
2-km exclusion zone.



Geologic Summary. Reports from this remote volcano in northernmost
Halmahera are rare, but Dukono has been one of Indonesia's most active
volcanoes. More-or-less continuous explosive eruptions, sometimes
accompanied by lava flows, occurred from 1933 until at least the mid-1990s,
when routine observations were curtailed. During a major eruption in 1550,
a lava flow filled in the strait between Halmahera and the north-flank cone
of Gunung Mamuya. This complex volcano presents a broad, low profile with
multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of
the summit crater complex, contains a 700 x 570 m crater that has also been
active during historical time.



Source: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml





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



Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of
Ebeko, observed bursts of gas, steam, and a small amount of ash that rose
up to 2.5 km (8,200 ft) a.s.l. on 13 and 17 March. Ash plumes drifted NE
and SE. The Aviation Color Code remained at Orange (the second highest
level on a four-color scale).



Geologic Summary. The flat-topped summit of the central cone of Ebeko
volcano, one of the most active in the Kuril Islands, occupies the northern
end of Paramushir Island. Three summit craters located along a SSW-NNE line
form Ebeko volcano proper, at the northern end of a complex of five
volcanic cones. Blocky lava flows extend west from Ebeko and SE from the
neighboring Nezametnyi cone. The eastern part of the southern crater
contains strong solfataras and a large boiling spring. The central crater
is filled by a lake about 20 m deep whose shores are lined with steaming
solfataras; the northern crater lies across a narrow, low barrier from the
central crater and contains a small, cold crescentic lake. Historical
activity, recorded since the late-18th century, has been restricted to
small-to-moderate explosive eruptions from the summit craters. Intense
fumarolic activity occurs in the summit craters, on the outer flanks of the
cone, and in lateral explosion craters.



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





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



On 16 March INSIVUMEH reported an increased number of avalanches at Fuego,
traveling down the Ceniza (SSW), Trinidad (S), and Las Lajas (SE) ravines.
A 600-m-long lava flow advanced down the Trinidad drainage. Weak explosive
activity accompanied lava effusion. There were 4-12 explosions per hour
recorded at Fuego during 17-24 March, generating ash plumes that rose as
high as 1.1 km above the crater rim and generally drifted 10-22 km S, SW,
and W. Almost daily ashfall was reported in several areas downwind
including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8
km SW), Finca Palo Verde, San Pedro Yepocapa (8 km NW), Sangre de Cristo (8
km WSW), El Porvenir (8 km ENE), and La Cruz. Explosions sometimes produced
shock waves that rattled nearby houses and were felt in communities within
a 25-km radius. Incandescent material was ejected 100-400 m high and caused
avalanches of material that occasionally traveled long distances (reaching
vegetated areas) down the Seca (W), Taniluyá (SW), Ceniza, Trinidad, Honda,
and Las Lajas ravines. Lava flows of variable lengths (400-1,000 m)
descended the Trinidad and Ceniza ravines each day but were inactive by the
evening of 23 March.



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) http://www.insivumeh.gob.gt/





Ibu  | Halmahera (Indonesia)  | 1.488°N, 127.63°E  | Summit elev. 1325 m



The Darwin VAAC reported that during 18-19 March ash plumes from Ibu rose
to 2.1 km (7,000 ft) a.s.l. and drifted W based on satellite images and
weather models. 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 active crater, and
3.5 km away on the N side.



Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along
the NW coast of Halmahera Island has large nested summit craters. The inner
crater, 1 km wide and 400 m deep, contained several small crater lakes
through much of historical time. The outer crater, 1.2 km wide, is breached
on the north side, creating a steep-walled valley. A large parasitic cone
is located ENE of the summit. A smaller one to the WSW has fed a lava flow
down the W flank. A group of maars is located below the N and W flanks.
Only a few eruptions have been recorded in historical time, the first a
small explosive eruption from the summit crater in 1911. An eruption
producing a lava dome that eventually covered much of the floor of the
inner summit crater began in December 1998.



Sources: Darwin Volcanic Ash Advisory Centre (VAAC)
http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml;

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





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



KVERT reported that Strombolian activity at Klyuchevskoy was visible during
13-20 March, and the number of hot avalanches descending all of the flanks
continued to increase. A bright thermal anomaly was identified daily in
satellite images. Gas-and-steam plumes containing some ash drifted as far
as 170 km E, NE, and N at altitudes of 5.5-6.5 km (18,000-21,300 ft) a.s.l.
during 15 and 18-19 March. Vulcanian activity was visible on 19 March. The
Aviation Color Code remained at Orange.



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



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





Krakatau  | Indonesia  | 6.102°S, 105.423°E  | Summit elev. 155 m



PVMBG reported that on 18 March a dense white-gray plume rose 300 m above
the summit of Anak Krakatau and drifted S. The event lasted just over 10
minutes based on seismic data. The Alert Level remained at 2 (on a scale of
1-4), and the public was warned to remain outside of the 2-km-radius hazard
zone from the crater.



Geologic Summary. The renowned volcano Krakatau (frequently misstated as
Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of
the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a
7-km-wide caldera. Remnants of this ancestral volcano are preserved in
Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan
volcanoes were formed, coalescing to create the pre-1883 Krakatau Island.
Caldera collapse during the catastrophic 1883 eruption destroyed Danan and
Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd
largest in Indonesia during historical time, caused more than 36,000
fatalities, most as a result of devastating tsunamis that swept the
adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km
across the Sunda Strait and reached the Sumatra coast. After a quiescence
of less than a half century, the post-collapse cone of Anak Krakatau (Child
of Krakatau) was constructed within the 1883 caldera at a point between the
former cones of Danan and Perbuwatan. Anak Krakatau has been the site of
frequent eruptions since 1927.



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





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 small and periodic ash-and-gas
emissions from Nevado del Ruiz were visible in satellite and webcam images
during 18-24 March. These emissions drifted NE and SE. A gas-and-steam
plume rose 1.5 km above the crater rim on 23 March. The Alert Level
remained at 3 (Yellow; the second lowest level on a four-color 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://www2.sgc.gov.co/volcanes/index.html





Pacaya  | Guatemala  | 14.382°N, 90.601°W  | Summit elev. 2569 m



INSIVUMEH reported that during 17-24 March Strombolian explosions at
Pacayaâ??s Mackenney Crater ejected material as high as 100 m above the
crater rim. Multiple lava flows (as many as four per day) traveled 100-300
m NW, W, and SW flanks.



Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active
volcanoes, are frequently visible from Guatemala City, the nation's
capital. This complex basaltic volcano was constructed just outside the
southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A
cluster of dacitic lava domes occupies the southern caldera floor. The
post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro
Grande stratovolcanoes and the currently active Mackenney stratovolcano.
Collapse of Pacaya Viejo between 600 and 1500 years ago produced a
debris-avalanche deposit that extends 25 km onto the Pacific coastal plain
and left an arcuate somma rim inside which the modern Pacaya volcano
(Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on
the NW somma rim and was last active in the 19th century. During the past
several decades, activity has consisted of frequent strombolian eruptions
with intermittent lava flow extrusion that has partially filled in the
caldera moat and armored the flanks of Mackenney cone, punctuated by
occasional larger explosive eruptions that partially destroy the summit of
the growing young stratovolcano.



Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e
Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/





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



CENAPRED reported that each day during 17-23 March there were 74-182
steam-and-gas emissions from Popocatépetl, some of which contained minor
amounts of ash. An explosion at 2210 on 17 March ejected incandescent
material onto the flanks and produced an ash plume that rose 1.2 km above
the crater rim and drifted SE. Minor ashfall was reported in the
municipalities of Tetela del Volcán (20 km SW), San Andrés and Hueyapan (16
km SW), and Ocuituco (24 km SW) during 17-18 March. Some emissions were
accompanied by incandescent material ejected out of the crater between
2229-2315 on 18 March. An explosion at 1928 on 19 March ejected
incandescent material a short distance from the crater. On 22 March an ash
plume rose 1 km and drifted S and ejected incandescent tephra fell onto the
flanks at a distance of 800 m from the crater. The Alert Level remained at
Yellow, Phase Two (middle level on a three-color scale).



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://www.gob.mx/cenapred





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



IG reported that during 17-24 March seismic data from Reventadorâ??s network
indicated a high level of seismic activity, including explosions,
long-period earthquakes, and signals indicating emissions. Gas-and-ash
emissions were observed almost daily, though cloudy weather often prevented
views of the volcano; IG and the Washington VAAC reported gas-and-ash
emissions rising around 500-900 m above the crater rim, and as high as 2
km, and drifting NE, SE, S, and W. Ashfall was reported in San Rafael (8 km
ESE) on 17 March. Incandescent blocks rolled 900 m down the S and SE flanks
during 23-24 March.



Geologic Summary. 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 Volcán El Reventador
stratovolcano rises to 3562 m above the jungles of the western Amazon
basin. A 4-km-wide caldera widely breached to the east was formed by
edifice collapse and is partially filled by a young, unvegetated
stratovolcano that rises about 1300 m above the caldera floor to a height
comparable to the caldera rim. It has been the source of numerous lava
flows as well as explosive eruptions that were visible from Quito in
historical time. Frequent lahars in this region of heavy rainfall have
constructed a debris plain on the eastern floor of the caldera. The largest
historical 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.



Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
http://www.igepn.edu.ec/





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



INSIVUMEH reported that explosions at Santa María's Santiaguito lava-dome
complex generated ash plumes that rose 500-900 m above the crater and
drifted as far as 1 km NW, W, and SW. Avalanches of blocks descended the
SE, E, S, and SW flanks of Caliente cone.



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) http://www.insivumeh.gob.gt/





Semisopochnoi  | United States  | 51.93°N, 179.58°E  | Summit elev. 1221 m



AVO reported that activity at Semisopochnoi had decreased compared to the
previous week. Seismicity remained elevated during 19-24 March and no
surface activity was observed on most days, though weather clouds often
prevented visual confirmation. A steam plume was visible in a satellite
image on 21 March and weakly elevated surface temperatures were identified
in one satellite image during 21-22 March. The Aviation Color Code remained
at Orange and the Volcano Alert Level remained at Watch.



Geologic Summary. Semisopochnoi, the largest subaerial volcano of the
western Aleutians, is 20 km wide at sea level and contains an 8-km-wide
caldera. It formed as a result of collapse of a low-angle, dominantly
basaltic volcano following the eruption of a large volume of dacitic
pumice. The high point of the island is 1221-m-high Anvil Peak, a
double-peaked late-Pleistocene cone that forms much of the island's
northern part. The three-peaked 774-m-high Mount Cerberus volcano was
constructed during the Holocene within the caldera. Each of the peaks
contains a summit crater; lava flows on the northern flank of Cerberus
appear younger than those on the southern side. Other post-caldera
volcanoes include the symmetrical 855-m-high 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 historical eruptions have
originated from Cerberus, although Coats (1950) considered that both
Sugarloaf and Lakeshore Cone within the caldera could have been active
during historical time.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://avo.alaska.edu/





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 13-20 March. The Aviation Color Code remained at
Orange (the second highest level on a four-color scale).



Geologic Summary. The high, isolated massif of Sheveluch volcano (also
spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya
volcano group. The 1300 km3 volcano is one of Kamchatka's largest and most
active volcanic structures. The summit of roughly 65,000-year-old Stary
Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera
breached to the south. Many lava domes dot its outer flanks. The Molodoy
Shiveluch lava dome complex was constructed during the Holocene within the
large horseshoe-shaped caldera; Holocene lava dome extrusion also took
place on the flanks of Stary Shiveluch. At least 60 large eruptions have
occurred during the Holocene, making it the most vigorous andesitic volcano
of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions
have provided valuable time markers for dating volcanic events in
Kamchatka. Frequent collapses of dome complexes, most recently in 1964,
have produced debris avalanches whose deposits cover much of the floor of
the breached caldera.



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





Shishaldin  | Fox Islands (USA)  | 54.756°N, 163.97°W  | Summit elev. 2857 m



AVO reported that seismicity at Shishaldin was characterized as
near-continuous tremor during 18-20 March and continuous tremor during
21-24 March. Steam-and-gas plumes rising from the summit crater were
recorded daily by the webcam and sometimes identified in satellite images.
Elevated surface temperatures, consistent with lava in the summit crater,
were also identified in satellite images. The Volcano Alert Level remained
at Watch and the Aviation Color Code remained at Orange.



Geologic Summary. The beautifully symmetrical Shishaldin is the highest and
one of the most active volcanoes of the Aleutian Islands. The
glacier-covered volcano is the westernmost of three large stratovolcanoes
along an E-W line in the eastern half of Unimak Island. The Aleuts named
the volcano Sisquk, meaning "mountain which points the way when I am lost."
A steam plume often rises from its small summit crater. Constructed atop an
older glacially dissected volcano, it is largely basaltic in composition.
Remnants of an older ancestral volcano are exposed on the W and NE sides at
1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its
NW flank, which is blanketed by massive aa lava flows. Frequent explosive
activity, primarily consisting of Strombolian ash eruptions from the small
summit crater, but sometimes producing lava flows, has been recorded since
the 18th century.



Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://avo.alaska.edu/





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



JMA reported that during 13-19 March incandescence from Suwanosejimaâ??s
Ontake Crater was visible nightly. On 14 March an ash plume rose 400 m
above the crater rim. On 23 March the Tokyo VAAC reported that an explosion
produced an ash plume that rose to an altitude of 0.9 km (3,000 ft) a.s.l.,
or 120 m above the summit, and drifted SE. The Alert Level remained at 2
(on a 5-level scale).



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



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

Tokyo Volcanic Ash Advisory Center (VAAC)
http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html




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End of Volcano Digest - 20 Mar 2020 to 25 Mar 2020 (#2020-34)
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