Thursday, December 22, 2011

[ Volcano ] Smithsonian/USGS Weekly Volcanic Activity Report 2-8 November 2011

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Smithsonian/USGS Weekly Volcanic Activity Report 2-8 November 2011
From: "Kuhn, Sally" <KUHNS@si.edu>
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Smithsonian/USGS Weekly Volcanic Activity Report

2-8 November 2011

Sally Kuhn Sennert - Weekly Report Editor

kuhns@si.edu

URL: http://www.volcano.si.edu/reports/usgs/

New Activity/Unrest: | Cerro Hudson, Southern Chile | Hierro, Canary Islands
(Spain) | Nyamuragira, Democratic Republic of Congo

Ongoing Activity: | Cleveland, Chuginadak Island | Dukono, Halmahera | Karymsky,
Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka
(Russia) | Kliuchevskoi, Central Kamchatka (Russia) | Pagan, Mariana Islands |
Puyehue-Cord?n Caulle, Central Chile | Sakura-jima, Kyushu | Santa Mar?a,
Guatemala | Shiveluch, Central Kamchatka (Russia) | Soufri?re Hills, Montserrat

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

CERRO HUDSON Southern Chile 45.90?S, 72.97?W; summit elev. 1905 m

On 2 November, OVDAS-SERNAGEOMIN reported that the Alert Level for Cerro Hudson
was lowered to Yellow, Level 4, noting that the eruption that began on 26
October had ceased. ONEMI reported that the 140 evacuees were permitted to
return home. Analysis of ash deposited on the edge of the crater during the
eruption indicated the presence of juvenile basalt. During 1-6 November between
16 and 110 earthquakes per day were recorded and satellite images showed
drifting plumes daily.

Geologic Summary. The ice-filled, 10-km-wide caldera of the remote Cerro Hudson
volcano was not recognized until its first 20th-century eruption in 1971. Cerro
Hudson is the southernmost volcano in the Chilean Andes related to subduction of
the Nazca plate beneath the South American plate. The massive, 1905-m-high Cerro
Hudson covers an area of 300 sq km. The compound caldera is drained through a
breach on its NW rim, which has been the source of mudflows down the R?o de Los
Huemeles. Two cinder cones occur north of the volcano and others occupy the SW
and SE flanks. Hudson has been the source of several major Holocene explosive
eruptions. An eruption about 6700 years ago was one of the largest known in the
southern Andes during the Holocene; another eruption about 3600 years ago also
produced more than 10 cu km of tephra. An eruption in 1991 was Chile's second
largest of the 20th century and formed a new 800-m-wide crater in the SW part
of the caldera.

Sources: Servicio Nacional de Geolog?a y Miner?a (SERNAGEOMIN)
http://www.sernageomin.cl/,

Oficina Nacional de Emergencia - Ministerio del Interior (ONEMI)
http://www.onemi.cl/

HIERRO Canary Islands (Spain) 27.73?N, 18.03?W; summit elev. 1500 m

Instituto Geogr?fico Nacional (IGN) reported that during 2-8 November the
submarine eruption continued S of El Hierro Island. Tremor amplitude reached
higher values than during previous weeks, getting closer to the values detected
during 11-12 October, just after the beginning of the eruption. During 3-4
November an increase of the activity could be observed over the submarine
emission center, with large circles of light blue color on the sea surface,
followed by foam rings and turbulent water with volcanic material. Close to
sunset on 5 November, big bubbles rose to the sea surface and ejected sea water
and volcanic material a few meters above the water. This activity continued
during the following days.

During 2-8 November, 364 seismic events were recorded, most of them located
offshore to the N of the island, at depths of 16-23 km. The maximum magnitude
was 4.4, and 32 of these events were felt by residents at a maximum intensity
value of V using EMS-98 (European Macroseismic Scale). The total number of
located events since 17 July was 11,294. GPS deformation analysis showed trends
towards no deformation during the first days of the reported period, and a
slight trend towards deformation to the S at the stations located on the N side
of the island in the last days.

During 4-5 November authorities evacuated about 80 residents from areas in
Frontera due to landslide risks from seismic activity. Residents of La Restinga
were evacuated on 5 November. According to a news article, ships and aircraft
were banned from the area.

Geologic Summary. The triangular island of Hierro is the SW-most and least
studied of the Canary Islands. The massive Hierro shield volcano is truncated
by a large NW-facing escarpment formed as a result of gravitational collapse of
El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp
towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three
other large submarine landslide deposits occur to the SW and SE. Three
prominent rifts oriented NW, NE, and south at 120 degree angles form prominent
topographic ridges. The subaerial portion of the volcano consists of flat-lying
Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous
young cinder cones and lava flows. Holocene cones and flows are found both on
the outer flanks and in the El Golfo depression. Hierro contains the greatest
concentration of young vents in the Canary Islands. Uncertainty surrounds the
report of an historical eruption in 1793.

Sources: Instituto Geogr?fico Nacional (IGN)

http://www.01.ign.es/ign/layout/volcaVolcanologia.do,

Gobierno de Canaries http://www.gobcan.es/,

Associated Press http://www.msnbc.msn.com/id/45175621/ns/world_news-europe/

NYAMURAGIRA Democratic Republic of Congo 1.408?S, 29.20?E; summit elev. 3058 m

Virunga National Park reported that on 6 November a fissure eruption from
Nyamuragira began low on the flank, producing slow-moving lava flows that
traveled into unpopulated areas to the N. The eruption was clearly observed
from the park headquarters. Video posted on the park's website showed a fissure
eruption with lava fountains.

Geologic Summary. Africa's most active volcano, Nyamuragira (Also spelled
Nyamulagira) is a massive basaltic shield volcano N of Lake Kivu and NW of
Nyiragongo volcano. Lava flows from Nyamuragira cover 1,500 sq km of the East
African Rift. The 3058-m-high summit is truncated by a small 2 x 2.3 km summit
caldera that has walls up to about 100 m high. About 40 historical eruptions
have occurred since the mid-19th century within the summit caldera and from
numerous fissures and cinder cones on the volcano's flanks. A lava lake in the
summit crater, active since at least 1921, drained in 1938. Twentieth-century
flank lava flows extend more than 30 km from the summit, reaching as far as
Lake Kivu.

Sources: Gorilla.cd, Virunga National Park, DR Congo http://gorillacd.org/

Ongoing Activity

CLEVELAND Chuginadak Island 52.825?N, 169.944?W; summit elev. 1730 m

AVO reported that a thermal anomaly over the lava dome surface in Cleveland's
summit crater was visible on 2 November, although cloudy views mostly prevented
observations. On 3 November AVO lowered the Volcano Alert Level to Advisory and
the Aviation Color Code to Yellow because satellite observations indicated no
significant change in the size of the lava dome, and no explosive activity or
ash emissions had been reported. Cloud cover continued to prevent observations
during 4-6 November. Satellite imagery showed slightly elevated temperatures
near the volcano's summit during 6-7 November. No current seismic information
was available because Cleveland does not have a real-time seismic network.

Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the
western end of the uninhabited dumbbell-shaped Chuginadak Island in the
east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the
Islands of Four Mountains group and is one of the most active in the Aleutians.
Numerous large lava flows descend its flanks. It is possible that some 18th to
19th century eruptions attributed to Carlisle (a volcano located across the
Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944
Cleveland produced the only known fatality from an Aleutian eruption. Recent
eruptions from Mt. Cleveland have been characterized by short-lived explosive
ash emissions, at times accompanied by lava fountaining and lava flows down the
flanks.

Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/

DUKONO Halmahera 1.68?N, 127.88?E; summit elev. 1335 m

Based on analyses of satellite imagery, the Darwin VAAC reported that on 3
November an ash plume from Dukono rose to an altitude of 2.1 km (7,000 ft)
a.s.l. and drifted 75 km 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 N-flank cone of Gunung Mamuya. Dukono is a complex
volcano presenting a broad, low profile with multiple summit peaks and
overlapping craters. Malupang Wariang, 1 km SW of Dukono's 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.ssd.noaa.gov/VAAC/OTH/AU/messages.html

KARYMSKY Eastern Kamchatka (Russia) 54.05?N, 159.45?E; summit elev. 1536 m

KVERT reported that seismic activity continued at a moderate level at Karymsky
during 28 October-4 November, and indicated that possible ash plumes rose to an
altitude of 4.5 km (14,800 ft) a.s.l. during 27-30 October and 1-2 November.
Satellite imagery showed ash plumes drifting 130 km SE during 29-30 October and
a thermal anomaly on the volcano during 29-31 October. The Aviation Color Code
remained at Orange.

Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern
volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide
caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of
the Karymsky stratovolcano began about 2,000 years later. The latest eruptive
period began about 500 years ago, following a 2,300-year quiescence. Much of
the cone is mantled by lava flows less than 200 years old. Historical eruptions
have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity
and occasional lava flows from the summit crater. Most seismicity preceding
Karymsky eruptions has originated beneath Akademia Nauk caldera, which is
located immediately S of Karymsky volcano and erupted simultaneously with
Karymsky in 1996.

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

KILAUEA Hawaii (USA) 19.421?N, 155.287?W; summit elev. 1222 m

During 2-8 November, HVO reported that the lava lake circulated and periodically
rose and fell in the deep pit within Kilauea's Halema'uma'u Crater, remaining
below the inner ledge (75 m below the crater floor). Almost daily measurements
indicated that the gas plume from the vent continued to deposit variable
amounts of ash and fresh spatter nearby. Incandescence emanated from the E and
W edges of the Pu'u 'O'o crater floor and from the 21 September fissure on the
upper E flank of the Pu'u 'O'o cone during most of the reporting period.
Pahoehoe flows, fed through lava tubes from the fissure, continued to be active
about 4.5 km SE of Pu'u 'O'o based on an overflight on 3 November and satellite
images acquired during 4-7 November.

Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the
island of Hawaii, is one of the world's most active volcanoes. Eruptions at
Kilauea originate primarily from the summit caldera or along one of the lengthy
E and SW rift zones that extend from the caldera to the sea. About 90% of the
surface of Kilauea is formed of lava flows less than about 1,100 years old; 70%
of the volcano's surface is younger than 600 years. A long-term eruption from
the East rift zone that began in 1983 has produced lava flows covering more
than 100 sq km, destroying nearly 200 houses and adding new coastline to the
island.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
http://hvo.wr.usgs.gov/

KIZIMEN Eastern Kamchatka (Russia) 55.130?N, 160.32?E; summit elev. 2376 m

KVERT reported moderate seismic activity at Kizimen during 28 October-4
November; the number of volcanic earthquakes increased. A thermal anomaly on
the volcano was detected daily in satellite images. A large lava flow on the NE
and E flanks continued to effuse and was visibly incandescent at night. Video
observations showed gas-and-steam activity during 28 October-2 November. A
large lava flow on the NE flank continued to effuse, and incandescence from
both the crater and the lava flows was noted at night. The Aviation Color Code
remained at Orange.

Geologic Summary. Kizimen is an isolated, conical stratovolcano that is
morphologically similar to Mount St. Helens prior to its 1980 eruption. The
summit of Kizimen consists of overlapping lava domes, and blocky lava flows
descend the flanks of the volcano, which is the westernmost of a volcanic chain
north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four
eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years.
The largest eruptions took place about 10,000 and 8300-8400 years ago, and three
periods of longterm lava-dome growth have occurred. The latest eruptive cycle
began about 3,000 years ago with a large explosion and was followed by
lava-dome growth lasting intermittently about 1,000 years. An explosive
eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7
km wide crater breached to the NE, inside which a small lava dome (the fourth at
Kizimen) has grown. A single explosive eruption, during 1927-28, has been
recorded in historical time.

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

KLIUCHEVSKOI Central Kamchatka (Russia) 56.057?N, 160.638?E; summit elev. 4835 m

The Tokyo VAAC reported that a possible ash plume from Kliuchevskoi, drifting at
an altitude of 6.7 km (22,000 ft) a.s.l., was observed in satellite imagery. The
VAAC noted that the ash plume may have been from Bezymianny.

Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano.
Since its origin about 7,000 years ago, the beautifully symmetrical,
4,835-m-high basaltic stratovolcano has produced frequent moderate-volume
explosive and effusive eruptions without major periods of inactivity. More than
100 flank eruptions, mostly on the NE and SE flanks of the conical volcano
between 500 m and 3,600 m elevation, have occurred during the past 3,000 years.
The morphology of its 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 major explosive and effusive events from flank craters.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html

PAGAN Mariana Islands 18.13?N, 145.80?E; summit elev. 570 m

A Northern Mariana Islands status report noted that clear to partly-cloudy
satellite images showed a persistent gas-and-steam plume drifting from Pagan
during 28 October-4 November. The Aviation Color Code remained at Yellow and
the Volcano Alert Level remained at Advisory.

Geologic Summary. Pagan Island, the largest and one of the most active of the
Mariana Islands volcanoes, consists of two stratovolcanoes connected by a
narrow isthmus. Both North and South Pagan stratovolcanoes were constructed
within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount
Pagan at the NE end of the island rises above the flat floor of the caldera,
which probably formed during the early Holocene. South Pagan is a 548-m-high
stratovolcano with an elongated summit containing four distinct craters. Almost
all of the historical eruptions of Pagan, which date back to the 17th century,
have originated from North Pagan volcano. The largest eruption of Pagan during
historical time took place in 1981 and prompted the evacuation of the sparsely
populated island.

Source: Emergency Management Office of the Commonwealth of the Mariana Islands,
Office of the Governor, United States Geological Survey Volcano Hazards Program
http://volcanoes.usgs.gov/nmi/activity/index.php

PUYEHUE-CORDON CAULLE Central Chile 40.590?S, 72.117?W; summit elev. 2236 m

Based on seismicity during 3-8 November, OVDAS-SERNAGEOMIN reported that the
eruption from the Cord?n Caulle rift zone, part of the Puyehue-Cord?n Caulle
volcanic complex, continued at a low level. During 3-6 November plumes observed
with an area web camera rose 5 km above the crater, and satellite imagery
showed active plumes drifting 30-120 km N, NE, E, and SE. Ash plumes dispersed
as far as 300 km NE and SE. Area cameras showed a plume rising 2 km above the
crater on 7 November. Cloud cover prevented observations of the plume with the
area camera the next day and from satellite during 7-8 November. The Alert
Level remained at Red.

Geologic Summary. The Puyehue-Cord?n Caulle volcanic complex (PCCVC) is a large
NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse
volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada
caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end
by the Cord?n Caulle fissure complex. The Pleistocene Mencheca volcano with
Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue
volcano is the most geochemically diverse of the PCCVC. The flat-topped,
2236-m-high Puyehue volcano was constructed above a 5-km-wide caldera and is
capped by a 2.4-km-wide summit caldera of Holocene age. Lava flows and domes of
mostly rhyolitic composition are found on the eastern flank of Puyehue.
Historical eruptions originally attributed to Puyehue, including major
eruptions in 1921-22 and 1960, are now known to be from the Cord?n Caulle rift
zone. The Cord?n Caulle geothermal area, occupying a 6 x 13 km wide
volcano-tectonic depression, is the largest active geothermal area of the
southern Andes volcanic zone.

Source: Servicio Nacional de Geolog?a y Miner?a (SERNAGEOMIN)
http://www.sernageomin.cl/

SAKURA-JIMA Kyushu 31.585?N, 130.657?E; summit elev. 1117 m

Based on information from JMA, the Tokyo VAAC reported that during 2-3 and 5-7
November explosions from Sakura-jima produced plumes that rose to altitudes of
1.8-3 km (6,000-10,000 ft) a.s.l. and drifted W, NW, N, and SE.

Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a
post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay.
Eruption of the voluminous Ito pyroclastic flow was associated with the
formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The
construction of Sakura-jima began about 13,000 years ago and built an island
that was finally joined to the Osumi Peninsula during the major explosive and
effusive eruption of 1914. Activity at the Kita-dake summit cone ended about
4,850 years ago, after which eruptions took place at Minami-dake. 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: Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html

SANTA MARIA Guatemala 14.756?N, 91.552?W; summit elev. 3772 m

INSIVUMEH reported that during 1-2 November explosions from Santa Mar?a's
Santiaguito lava-dome complex generated ash plumes that rose 600-1,000 m above
the complex and drifted S and SW, causing ashfall in villages downwind. The
explosions were heard in areas 12 km to the S and SW. Lava flows on the SE and
S flanks generated block avalanches. During 3-4 and 7-8 November explosions
produced ash plumes that rose 500-800 m above the complex and drifted SW and W.
Explosions and rumbling were heard in areas to the S and SW. Lava flows on the
SE flank continued to generate block avalanches.

Based on analyses of satellite imagery, the Washington VAAC reported that during
5-6 November possible ash plumes drifted 18-28 km SE and a thermal anomaly over
the volcano was detected. On 8 November a possible ash plume drifted 45 km SW,
coincident with an enhanced thermal anomaly.

Geologic Summary. Symmetrical, forest-covered Santa Mar?a volcano is one of a
chain of large stratovolcanoes that rises dramatically above the Pacific
coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical
profile that is cut on the SW flank by a large, 1-km-wide crater, which formed
during a catastrophic eruption in 1902 and extends from just below the summit
to the lower flank. The renowned Plinian eruption of 1902 followed a long
repose period and devastated much of SW Guatemala. The large 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 westward-younging vents, accompanied by almost continuous minor explosions
and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

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

Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html

SHIVELUCH Central Kamchatka (Russia) 56.653?N, 161.360?E; summit elev. 3283 m

KVERT reported strong seismic activity at Shiveluch during 28 October-4
November, and indicated that possible ash plumes rose to an altitude of 7.8 km
(25,600 ft) a.s.l. on 29 October and to lower altitudes on other days.
Ground-based observers noted strong fumarolic activity at the lava dome during
29 October-1 November; cloud cover prevented observations on the other days.
Satellite imagery showed a large daily thermal anomaly over the lava dome and
gas-and-steam plumes containing small amounts of ash that drifted 150 km E and
SE during 31 October and 1-2 November. The Aviation Color Code remained at
Orange.

Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled
Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and
forms one of Kamchatka's largest and most active volcanoes. The currently
active Molodoy Shiveluch lava-dome complex was constructed during the Holocene
within a large breached caldera formed by collapse of the massive
late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of
Shiveluch have occurred during the Holocene, making it the most vigorous
andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome
complexes, most recently in 1964, have produced large debris avalanches whose
deposits cover much of the floor of the breached caldera. Intermittent
explosive eruptions began in the 1990s from a new lava dome that began growing
in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and
1964.

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

SOUFRIERE HILLS Montserrat 16.72?N, 62.18?W; summit elev. 915 m

MVO reported that during 28 October-4 November activity at the Soufri?re Hills
lava dome was at a low level. On 4 November the Hazard Level was lowered to 2
because of a considerable reduction in the number of spontaneous pyroclastic
flows from the remaining lava dome over approximately the last year. The
reduction in Hazard Level allowed people to have daytime access to Zone C to
the W of the lava dome, including Cork Hill, Weekes, Richmond Hill, Delvins,
and Foxes Bay. Other minor changes to hazard zone borders were also
implemented.

Geologic Summary. The complex dominantly andesitic Soufri?re Hills volcano
occupies the southern half of the island of Montserrat. The summit area
consists primarily of a series of lava domes emplaced along an ESE-trending
zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed
during an eruption about 4,000 years ago in which the summit collapsed,
producing a large submarine debris avalanche. Block-and-ash flow and surge
deposits associated with dome growth predominate in flank deposits at Soufri?re
Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th
century, but with the exception of a 17th-century eruption that produced the
Castle Peak lava dome, no historical eruptions were recorded on Montserrat
until 1995. Long-term small-to-moderate ash eruptions beginning in that year
were later accompanied by lava-dome growth and pyroclastic flows that forced
evacuation of the southern half of the island and ultimately destroyed the
capital city of Plymouth, causing major social and economic disruption.

Source: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/

+++++++++++++++++++++++++++++++++++++
Sally Kuhn Sennert
SI/USGS Weekly Volcanic Activity Report Editor
Global Volcanism Program
http://www.volcano.si.edu/reports/usgs/
Smithsonian Institution, National Museum of Natural History
Department of Mineral Sciences, MRC-119
Washington, D.C., 20560
Phone: 202.633.1805
Fax: 202.357.2476


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