Smithsonian / USGS Weekly Volcanic Activity Report 27 November-3 December 2019

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


Smithsonian / USGS Weekly Volcanic Activity Report

27 November-3 December 2019



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

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





New Activity/Unrest: White Island, North Island (New Zealand)



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Etna, Sicily (Italy)  | Ibu, Halmahera
(Indonesia)  | Karangetang, Siau Island (Indonesia)  | Klyuchevskoy,
Central Kamchatka (Russia)  | Krakatau, Indonesia  | Nevados de Chillan,
Chile  | Popocatepetl, Mexico  | Sabancaya, Peru  | Sangeang Api,
Indonesia  | Sheveluch, Central Kamchatka (Russia)  | Shishaldin, Fox
Islands (USA)  | Stromboli, Aeolian Islands (Italy)





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





White Island  | North Island (New Zealand)  | 37.52°S, 177.18°E  | Summit
elev. 321 m



On 3 December GeoNet reported that unrest at White Island had continued
during the previous week. Explosive gas-and-steam-driven fountaining
occurred from the active vent area on the W side of the 1978/90 Crater
Complex, near the 2012 lava dome, at the back of the crater lake. Mud and
debris were ejected 20-30 m above the vent. The Volcanic Alert Level
remained at 2 and the Aviation Color Code remained at Yellow.



Geologic Summary. Uninhabited 2 x 2.4 km White Island, one of New Zealand's
most active volcanoes, is the emergent summit of a 16 x 18 km submarine
volcano in the Bay of Plenty about 50 km offshore of North Island. The
island consists of two overlapping andesitic-to-dacitic stratovolcanoes;
the summit crater appears to be breached to the SE, because the shoreline
corresponds to the level of several notches in the SE crater wall. Volckner
Rocks, four sea stacks that are remnants of a lava dome, lie 5 km NNE.
Intermittent moderate phreatomagmatic and strombolian eruptions have
occurred throughout the short historical period beginning in 1826, but its
activity also forms a prominent part of Maori legends. Formation of many
new vents during the 19th and 20th centuries has produced rapid changes in
crater floor topography. Collapse of the crater wall in 1914 produced a
debris avalanche that buried buildings and workers at a sulfur-mining
project.



Source: GeoNet http://www.geonet.org.nz/





Ongoing Activity





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



JMA reported that incandescence from Minamidake Crater (at Aira Calderaâ??s
Sakurajima volcano) was visible at night during 25 November-2 December.
There were 16 explosions and three non-explosive eruptive events detected
by the seismic network. Ash plumes rose as high as 2.7 km above the crater
rim and blocks were ejected as far as 1.3 km away. One of the explosions,
recorded at 2010 on 28 November, produced an eruption plume that rose 3.3
km. 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



Based on satellite and wind model data, and information from PVMBG, the
Darwin VAAC reported that during 27 November-3 December ash plumes from
Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE, E,
and NE. 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 explosions during 22-23 and 28 November that sent ash
plumes up to 2.5 km (8,200 ft) a.s.l. Ash plumes drifted SE and E, and
produced ashfall in Severo-Kurilsk on 23 November. 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





Etna  | Sicily (Italy)  | 37.748°N, 14.999°E  | Summit elev. 3295 m



INGV reported that eruptive activity at Etnaâ??s summit craters continued
during 25 November-1 December. Strombolian explosions at Voragine Crater
(VOR) occurred at intervals of 5-10 minutes, and many incandescent jets
rose above the crater rim. Some explosions created incandescent flashes in
emissions rising above the crater rim. A cone which had started forming on
the crater floor in mid-September had continued to grow according to
observations by field guides. Sporadic ash emissions began at New Southeast
Crater (NSEC) on the evening of 30 November, and a single Strombolian
explosion was recorded on 1 December. Incandescence from Bocca Nuova Crater
was intermittently visible at night.



Geologic Summary. Mount Etna, towering above Catania, Sicily's second
largest city, has one of the world's longest documented records of
historical volcanism, dating back to 1500 BCE. Historical lava flows of
basaltic composition cover much of the surface of this massive volcano,
whose edifice is the highest and most voluminous in Italy. The Mongibello
stratovolcano, truncated by several small calderas, was constructed during
the late Pleistocene and Holocene over an older shield volcano. The most
prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km
horseshoe-shaped caldera open to the east. Two styles of eruptive activity
typically occur, sometimes simultaneously. Persistent explosive eruptions,
sometimes with minor lava emissions, take place from one or more summit
craters. Flank vents, typically with higher effusion rates, are less
frequently active and originate from fissures that open progressively
downward from near the summit (usually accompanied by Strombolian eruptions
at the upper end). Cinder cones are commonly constructed over the vents of
lower-flank lava flows. Lava flows extend to the foot of the volcano on all
sides and have reached the sea over a broad area on the SE flank.



Source: Sezione di Catania - Osservatorio Etneo (INGV)
http://www.ct.ingv.it/





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



Based on PVMBG observations and satellite images, the Darwin VAAC reported
that on 3 December an ash plume from Ibu rose to 2.1 km (7,000 ft) a.s.l.
and drifted NE. A thermal anomaly was visible in satellite images.



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.



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





Karangetang  | Siau Island (Indonesia)  | 2.781°N, 125.407°E  | Summit
elev. 1797 m



PVMBG reported that during 25 November-1 December lava continued to effuse
from Karangetangâ??s Main Crater (S), traveling as far as 1.8 km down the
Nanitu, Pangi, and Sense drainages on the SW and W flanks. Sometimes dense
white plumes rose to 500 m above the summit. Incandescence from both summit
craters was visible at night. The Alert Level remained at 2 (on a scale of
1-4).



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
island. 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 in the historical record (Catalog of Active Volcanoes of the
World: 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) 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
21 and 26-27 November, and a weak thermal anomaly was identified in
satellite images during 21-25 and 28 November. 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 at 0543 on 27 October an eruptive event at Anak
Krakatau ejected a white-and-black plume 150 m above the active vent. 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/





Nevados de Chillan  | Chile  | 36.868°S, 71.378°W  | Summit elev. 3180 m



SERNAGEOMIN reported that during 26 November-3 December white-to-gray
plumes from Nevados de Chillánâ??s Nicanor Crater rose as high as 1.7 km
above the rim and drifted SE, NE, and NNW. Occasional explosions ejecting
incandescent material onto the flank were visible at night. The report
noted that the newest lava flow (L4) traveled down the NNE flank adjacent
to three previous flows (L1, L2, and L3). The point of emission of L4 was
about 60 m SSE of the emission point for the previous three lava flows. L4
had two lobes and was about 90 m long, measured from the rim of Nicanor
Crater, on 27 November. By 29 November it had lengthened to 165 m. The
volcano Alert Level remained at Orange, the second highest level on a
four-color scale. ONEMI maintained an Alert Level Yellow (the middle level
on a three-color scale) for the communities of Pinto, Coihueco, and San
Fabián, and stated that the public should stay at least 3 km away from the
crater on the SW flank and 5 km away on the ENE flank.



Geologic Summary. The compound volcano of Nevados de Chillán is one of the
most active of the Central Andes. Three late-Pleistocene to Holocene
stratovolcanoes were constructed along a NNW-SSE line within three nested
Pleistocene calderas, which produced ignimbrite sheets extending more than
100 km into the Central Depression of Chile. The largest stratovolcano,
dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW
end of the group. Volcán Viejo (Volcán Chillán), which was the main active
vent during the 17th-19th centuries, occupies the SE end. The new Volcán
Nuevo lava-dome complex formed between 1906 and 1945 between the two
volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau
dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and
eventually exceeded its height.



Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)
http://www.sernageomin.cl/





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



CENAPRED reported that each day during 26 November-3 December there were
124-187 steam-and-gas emissions from Popocatépetl, some of which contained
ash through 1 December. An explosion was recorded at 1036 on 26 November.
Another explosion at 0233 on 28 November produced an ash plume that rose 1
km above the crater rim and drifted NW. The event also ejected incandescent
material onto the flanks as far away as 1.5 km 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





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



Instituto Geofísico del Perú (IGP) reported that an average of 17 daily
low-to-medium intensity explosions occurred at Sabancaya during 25
November-1 December. Gas-and-ash plumes rose as high as 4 km above the
summit and drifted NE, E, and S. There were five thermal anomalies
identified in satellite data, originating from the 240-m-diameter lava dome
in the summit crater. 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) http://www.igp.gob.pe/





Sangeang Api  | Indonesia  | 8.2°S, 119.07°E  | Summit elev. 1912 m



The Darwin VAAC reported that during 27 November-3 December discrete and
short-lived ash emissions from Sangeang Api rose to altitudes of 2.4-3.3 km
(8,000-11,000 ft) a.s.l. and drifted NW, W, and SW. A thermal anomaly was
visible on 27 November. The Alert Level remained at 2 (on a scale of 1-4).



Geologic Summary. Sangeang Api volcano, one of the most active in the
Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of
Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic
cones, Doro Api and Doro Mantoi, were constructed in the center and on the
eastern rim, respectively, of an older, largely obscured caldera. Flank
vents occur on the south side of Doro Mantoi and near the northern coast.
Intermittent historical eruptions have been recorded since 1512, most of
them during in the 20th century.



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





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 22-29 November. 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 seismic levels at Shishaldin were variable but elevated
during 26 November-3 December. Weather clouds sometimes obscured satellite
image views and mostly prevented webcam views, though elevated surface
temperatures were still visible in multiple satellite images. An active
1.5-km-long lava flow on the NW flank was visible in satellite images on 1
December. Continuous tremor transitioned to episodic bursts during the
morning of 2 December, but by 3 December a decrease in seismic activity and
surface temperatures suggested another pause in lava effusion. The Aviation
Color Code remained at Orange and the Volcano Alert Level remained at Watch.



Geologic Summary. The beautifully symmetrical volcano of Shishaldin is the
highest and one of the most active volcanoes of the Aleutian Islands. The
2857-m-high, 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 steady steam plume rises from its small summit crater.
Constructed atop an older glacially dissected volcano, it is Holocene in
age and largely basaltic in composition. Remnants of an older ancestral
volcano are exposed on the west and NE sides at 1500-1800 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/





Stromboli  | Aeolian Islands (Italy)  | 38.789°N, 15.213°E  | Summit elev.
924 m



INGV reported that during 25 November-1 December activity at Stromboli was
characterized by ongoing explosive activity mainly from three vents in Area
N (north crater area) and at least three vents in Area C-S (south central
crater area). Low-to-medium-intensity explosions from Area N occurred at a
rate of 7-11 events per hour and ejected lapilli and bombs 80-150 m above
the vents. Ejected tephra fell onto the flanks and some blocks rolled a few
hundred meters along the Sciara del Fuoco. Medium-intensity explosions from
Area C-S occurred at a rate of 4-8 events per hour and ejected coarse
material to heights less than150 m above the vents. Material was deposited
along the upper parts of the Sciara del Fuoco.



Geologic Summary. Spectacular incandescent nighttime explosions at this
volcano have long attracted visitors to the "Lighthouse of the
Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its
name to the frequent mild explosive activity that has characterized its
eruptions throughout much of historical time. The small island is the
emergent summit of a volcano that grew in two main eruptive cycles, the
last of which formed the western portion of the island. The Neostromboli
eruptive period took place between about 13,000 and 5,000 years ago. The
active summit vents are located at the head of the Sciara del Fuoco, a
prominent horseshoe-shaped scarp formed about 5,000 years ago due to a
series of slope failures that extend to below sea level. The modern volcano
has been constructed within this scarp, which funnels pyroclastic ejecta
and lava flows to the NW. Essentially continuous mild Strombolian
explosions, sometimes accompanied by lava flows, have been recorded for
more than a millennium.



Source: Sezione di Catania - Osservatorio Etneo (INGV)
http://www.ct.ingv.it/



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