Smithsonian / USGS Weekly Volcanic Activity Report 7-13 November 2018

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

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

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





New Activity/Unrest: Mayon, Luzon (Philippines)  | Suwanosejima, Ryukyu
Islands (Japan)



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Fuego, Guatemala  | Kadovar, Papua New
Guinea  | Krakatau, Indonesia  | Merapi, Central Java (Indonesia)  | Rincon
de la Vieja, Costa Rica  | Sabancaya, Peru  | Semisopochnoi, United States
| Sheveluch, Central Kamchatka (Russia)  | Turrialba, Costa Rica  |
Veniaminof, United States





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, notices of
volcanic activity posted on these pages 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 on various volcanoes are published monthly in the Bulletin of the
Global Volcanism Network.



Note: 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





Mayon  | Luzon (Philippines)  | 13.257°N, 123.685°E  | Summit elev. 2462 m



PHIVOLCS reported that at 1243 on 8 November and at 0739 on 12 November
small, short-lived brownish ash plumes from Mayon, associated with a
degassing events, drifted WSW and SW, respectively. There was no
accompanying seismic or infrasound record from these events. On 11 November
a volcanic earthquake was associated with a short-lived lava fountaining
event at 0840. The event lasted for 36 seconds based on the seismic record
and produced a brownish-gray ash plume that drifted SW. Crater
incandescence was visible most nights during 7-13 November. The Alert Level
remained at 2 (on a 0-5 scale) and PHIVOLCS reminded residents to stay away
from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger
Zone on the SSW and ENE flanks.



Geologic Summary. Beautifully symmetrical Mayon, which rises above the
Albay Gulf NW of Legazpi City, is the Philippines' most active volcano. The
structurally simple edifice has steep upper slopes averaging 35-40 degrees
that are capped by a small summit crater. Historical eruptions date back to
1616 and range from Strombolian to basaltic Plinian, with cyclical activity
beginning with basaltic eruptions, followed by longer term andesitic lava
flows. Eruptions occur predominately from the central conduit and have also
produced lava flows that travel far down the flanks. Pyroclastic flows and
mudflows have commonly swept down many of the approximately 40 ravines that
radiate from the summit and have often devastated populated lowland areas.
A violent eruption in 1814 killed more than 1,200 people and devastated
several towns.



Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
http://www.phivolcs.dost.gov.ph/





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



JMA reported that an explosion at Suwanosejimaâ??s Ontake Crater was recorded
at 0428 on 9 November. A plume could not be confirmed because weather
clouds obscured views, but large pieces of pumice were observed being
ejected 700 m S. Explosions had not been recorded since 2 June. 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.



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





Ongoing Activity





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



JMA reported that the sulfur dioxide emission rate at Minamidake crater (at
Aira Calderaâ??s Sakurajima volcano) was high at 1,100 tons/day on 6
November, an increase from the previous measurement of 1,000 tons/day
recorded on 23 October. Very small eruptive events were occasionally
recorded during 9-12 November. The Alert Level remained at 3 (on a 5-level
scale).



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



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





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



PVMBG reported that an event at Dukono, recorded by the seismic network at
0824 on 8 November, generated an ash plume that rose 200 m above the crater
rim and drifted SW. The Darwin VAAC reported that during 12-13 November ash
plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted E and NE.



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



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

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





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



Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of
Ebeko, observed explosions during 2-9 November that sent ash plumes to 3.7
km (12,400 ft) a.s.l. Ash plumes drifted in multiple directions and caused
ashfall in Severo-Kurilsk. 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



INSIVUMEH reported that 7-18 explosions per hour were detected at Fuego
during 8-12 November. Ash plumes from the explosions rose as high as 1.1 km
above the crater rim and drifted 8-20 km W and SW. Ash fell in areas
downwind including Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de
Cristo (8 km WSW), Panimaché (8 km SW), El Porvenir, Finca Palo Verde, and
San Pedro Yepocapa (8 km NW). Incandescent material was ejected 150-300 m
high and caused avalanches that traveled far, reaching vegetated areas in
multiple drainages. Lava flows as long as 1.2 km advanced in the Ceniza
(SSW) drainage, though lava-flow activity greatly decreased by 12 November.



Geologic Summary. Volcán Fuego, one of Central America's most active
volcanoes, is one of three large stratovolcanoes overlooking Guatemala's
former capital, Antigua. The scarp of an older edifice, Meseta, lies
between 3763-m-high Fuego and its twin volcano to the north, Acatenango.
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 Acatenango. In contrast to 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.



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

Coordinadora Nacional para la Reducción de Desastres (CONRED)
http://conred.gob.gt/





Kadovar  | Papua New Guinea  | 3.608°S, 144.588°E  | Summit elev. 365 m



According to the Darwin VAAC an ash plume from Kadovar was identified in
satellite data on 9 November drifting WNW at an altitude of 1.8 km (6,000
ft) a.s.l.



Geologic Summary. The 2-km-wide island of Kadovar is the emergent summit of
a Bismarck Sea stratovolcano of Holocene age. Kadovar is part of the
Schouten Islands, and lies off the coast of New Guinea, about 25 km N of
the mouth of the Sepik River. The village of Gewai is perched on the crater
rim. A 365-m-high lava dome forming the high point of the andesitic volcano
fills an arcuate landslide scarp that is open to the south, and submarine
debris-avalanche deposits occur in that direction. Thick lava flows with
columnar jointing forms low cliffs along the coast. The youthful island
lacks fringing or offshore reefs. No certain historical eruptions are
known; the latest activity was a period of heightened thermal phenomena in
1976.



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





Krakatau  | Indonesia  | 6.102°S, 105.423°E  | Summit elev. 813 m



PVMBG reported that four events at Anak Krakatau occurred between 1620 and
1710 on 9 November. Each event lasted for 42-55 seconds, based on the
seismic data, and produced ash plumes that rose 300-500 m above the crater
rim and drifted N. An event at 0939 on 10 November generated an ash plume
that rose 500 m and drifted N. There were 10 events recorded during
1029-1656 on 12 November, each lasting 38-117 seconds, and producing ash
plumes that rose 200-700 m and drifted N. Four events were recorded during
0546-0840 on 13 November, each lasting 44-175 seconds, and producing ash
plumes that rose as high as 800 m. The Alert Level remained at 2 (on a
scale of 1-4); residents and visitors were warned not to approach the
volcano within 2 km of 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 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
volcanoes, and left only a remnant of Rakata volcano. 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/





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



PVMBG reported that during 2-8 November the lava dome in Merapiâ??s summit
crater grew slowly at a rate of 3,500 cubic meters per day, faster than the
previous week. By 7 November the volume of the dome, based on photos from
the SE sector, was an estimated 273,000 cubic meters. White emissions of
variable density rose a maximum of 100 m above the summit. The Alert Level
remained at 2 (on a scale of 1-4), and residents were warned to remain
outside of the 3-km exclusion zone.



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 2000 years ago, leaving a large arcuate scarp cutting the
eroded older Batulawang volcano. Subsequently growth of the steep-sided
Young Merapi edifice, its upper part unvegetated due to frequent eruptive
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 during historical time.



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





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



OVSICORI-UNA reported a two-minute-long eruption at Rincón de la Vieja
began at 1703 on 9 November. Weather conditions prevented webcam views and
estimates of plume heights.



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 that was 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 1916-m-high 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 3500 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) http://www.ovsicori.una.ac.cr/





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



Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio
Vulcanológico del INGEMMET (OVI) reported that an average of 18 explosions
per day occurred at Sabancaya during 5-11 November. Hybrid earthquakes were
infrequent and of low magnitude. Gas-and-ash plumes rose as high as 3.7 km
above the crater rim and drifted 40 km N, NW, and W. MIROVA detected seven
thermal anomalies, and on 8 November the sulfur-dioxide gas flux was high
at 2,500 tons per day. The report noted that the public should not approach
the crater within 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.



Sources: Instituto Geológico Minero y Metalúrgico (INGEMMET)
http://www.ingemmet.gob.pe/;

Instituto Geofísico del Perú (IGP) http://www.igp.gob.pe/





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



AVO reported that three possible small explosions at Semisopochnoi were
detected in infrasound data between 1951 and 2004 on 9 November. No
associated ash clouds were observed in partly cloudy satellite images, and
no other activity was noted during 7-11 November also in partly cloudy
images. Images were cloudy during 12-13 November. The Aviation Color Code
remained at Orange and Volcano Alert Level remained at Watch (both are the
second highest levels on four-level scales).



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 weak thermal anomaly over Sheveluch was identified in
satellite data on 2 and 6 November. Explosions at 1510 on 9 November
generated ash plumes that rose to 7 km (23,000 ft) a.s.l. and drifted 5 km
NE. 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





Turrialba  | Costa Rica  | 10.025°N, 83.767°W  | Summit elev. 3340 m



OVSICORI-UNA reported that during 6-11 November low-level ash-and-gas
emissions at Turrialba were continuous, though occasionally punctuated by
energetic explosions which elevated the plumes as high as 500 m above the
crater rim. The emission drifted towards the Valle Central. Ashfall was
reported in several areas downwind including Cascajal de Coronado,
Desamparados (35 km WSW), San Antonio, Guadalupe (32 km WSW), Sabanilla,
San Pedro Montes de Oca, Moravia (31 km WSW), Heredia (38 km W), and
Coronado (San José, 35 km WSW). Emissions likely continued on 12 November,
though inclement weather did not allow for visual confirmation.



Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene
volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located
across a broad saddle NE of Irazú volcano overlooking the city of Cartago.
The massive edifice covers an area of 500 km2. Three well-defined craters
occur at the upper SW end of a broad 800 x 2200 m summit depression that is
breached to the NE. Most activity originated from the summit vent complex,
but two pyroclastic cones are located on the SW flank. Five major explosive
eruptions have occurred during the past 3500 years. A series of explosive
eruptions during the 19th century were sometimes accompanied by pyroclastic
flows. Fumarolic activity continues at the central and SW summit craters.



Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad
Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/





Veniaminof  | United States  | 56.17°N, 159.38°W  | Summit elev. 2507 m



AVO reported that the eruption from the cone in Veniaminofâ??s ice-filled
summit caldera, continued at low levels during 7-13 November. Satellite and
webcam data showed elevated surface temperatures from minor lava spattering
and lava effusion. Continuous low-amplitude tremor was recorded. Steam and
diffuse ash plumes periodically identified in webcam and satellite images
rose as high as 3 km (10,000 ft) a.s.l. and drifted S and W. Recent
satellite data showed that the lava flows had traveled as far as 1.2 km
from the vent. Fractures in the ice sheet adjacent to the lava flow
continued to grow due to meltwater flowing beneath the ice sheet. The
Aviation Color Code remained at Orange (the second highest level on a
four-color scale) and the Volcano Alert Level remained at Watch (the second
highest level on a four-level scale).



Geologic Summary. Massive Veniaminof volcano, one of the highest and
largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled,
8 x 11 km, glacier-filled caldera that formed around 3700 years ago. The
caldera rim is up to 520 m high on the north, is deeply notched on the west
by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera
vents are located along a NW-SE zone bisecting the caldera that extends 55
km from near the Bering Sea coast, across the caldera, and down the Pacific
flank. Historical eruptions probably all originated from the westernmost
and most prominent of two intra-caldera cones, which rises about 300 m
above the surrounding icefield. The other cone is larger, and has a summit
crater or caldera that may reach 2.5 km in diameter, but is more subdued
and barely rises above the glacier surface.



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

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End of Volcano Digest - 8 Nov 2018 to 15 Nov 2018 (#2018-115)
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