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GVP/USGS Weekly Volcanic Activity Report
28 March-3 April 2007
http://www.volcano.si.edu/reports/usgs/
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New Activity/Unrest: | Ambrym, Vanuatu | Batu Tara, Indonesia |
Reventador, Ecuador | Slamet, Indonesia | Tungurahua, Ecuador
Ongoing Activity: | Karangetang, Indonesia | Karymsky, Russia | Kilauea,
USA | Kliuchevskoi, Russia | Piton de la Fournaise, Reunion Island |
Popocatépetl, México | Rabaul, Papua New Guinea | Santa María, Guatemala
| Shiveluch, Russia | Soufrière Hills, Montserrat | St. Helens, USA |
Suwanose-jima, Japan | Ubinas, Perú
New Activity/Unrest
AMBRYM Ambrym Island, Vanuatu 16.25°S, 168.12°E; summit elev. 1,334 m
The Wellington VAAC reported that on 3 April pilots observed lava and
ash emissions from Ambrym. Ash plumes rose to altitudes below 2.4 km
(8,000 ft) a.s.l.
Geologic Summary. Ambrym, a large basaltic volcano with a 12-km-wide
caldera, is one of the most active volcanoes of the New Hebrides arc. A
thick, almost exclusively pyroclastic sequence, initially dacitic, then
basaltic, overlies lava flows of a pre-caldera shield volcano. The
caldera was formed during a major plinian eruption with dacitic
pyroclastic flows about 1900 years ago. Post-caldera eruptions,
primarily from Marum and Benbow cones, have partially filled the caldera
floor and produced lava flows that ponded on the caldera floor or
overflowed through gaps in the caldera rim. Post-caldera eruptions have
also formed a series of scoria cones and maars along a fissure system
oriented ENE-WSW. Eruptions have apparently occurred almost yearly
during historical time from cones within the caldera or from flank
vents. However, from 1850 to 1950, reporting was mostly limited to
extra-caldera eruptions that would have affected local populations.
Source: Wellington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html
Ambrym Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-04=
BATU TARA Lesser Sunda Islands, Indonesia 7.792°S, 123.579°E; summit
elev. 748 m
Based on satellite imagery and CVGHM, the Darwin VAAC reported that
during 29 March-3 April semi-continuous emissions from Batu Tara
produced diffuse plumes. The plumes rose to altitudes of 1.5-3 km
(5,000-10,000 ft) a.s.l. and drifted E and N.
Geologic Summary. The small isolated island of Batu Tara in the Flores
Sea about 50 km north of Lomblen Island contains a scarp on the eastern
side similar to the Sciara del Fuoco of Italy's Stromboli volcano.
Vegetation covers the flanks of Batu Tara to within 50 m of the
748-m-high summit. Batu Tara lies north of the main volcanic arc and is
noted for its potassic leucite-bearing basanitic and tephritic rocks.
The only known historical eruption from Batu Tara, during 1847-52,
produced explosions and a lava flow.
Source: Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/info/vaac/advisories.shtml
Batu Tara Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0604-26=
REVENTADOR Ecuador 0.078°S, 77.656°W, summit elev. 3,562 m
On 28 March, observers reported roaring noises and an ash column from
Reventador that rose to an altitude of 5.6 km (18,400 ft) a.s.l. and
drifted W. A small lava flow traveled 200 m down the S flank.
Incandescent material and ash emissions were observed during 29-31
March. On 1 April, ash plumes rose to an altitude of 7.6 km (24,900 ft)
a.s.l. and incandescent rocks were ejected about 50 m above the crater.
Incandescent material was again seen at the summit on 2 April. The
Washington VAAC reported that a strong hotspot was present on satellite
imagery during 1-3 April. Based on pilot reports, IG reported that a
steam-and-gas plume with little ash content rose to an altitude of 6.1
km (20,000 ft) a.s.l. and drifted W on 3 April.
Geologic Summary. Reventador is the most frequently active of a chain of
Ecuadorian volcanoes in the Cordillera Real, well E of the principal
volcanic axis. It is a forested stratovolcano that rises above the
remote jungles of the western Amazon basin. A 3-km-wide caldera breached
to the E was formed by edifice collapse and is partially filled by a
young, unvegetated stratovolcano that rises about 1,300 m above the
caldera floor. Reventador 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.
Sources: Instituto Geofisico-Escuela Poltecnica Nacional
http://www.igepn.edu.ec/,
Washington Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/messages.html
Reventador Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-01=
SLAMET Indonesia 7.242°S, 109.208°E, summit elev. 3,428 m
According to a news article, a volcano observer monitoring Slamet
reported on 1 April that plume activity had increased in intensity and
frequency over the previous two weeks. Plumes rose to an estimated
altitude of 3.8 km (12,500 ft) a.s.l.
Geologic Summary. Slamet, Java's second highest volcano at 3428 m and
one of its most active, has a cluster of about three dozen cinder cones
on its lower SE-NE flanks and a single cinder cone on the western flank.
Slamet is composed of two overlapping edifices, an older
basaltic-andesite to andesitic volcano on the west and a younger
basaltic to basaltic-andesite one on the east. Gunung Malang II cinder
cone on the upper eastern flank on the younger edifice fed a lava flow
that extends 6 km to the east. Four craters occur at the summit of
Gunung Slamet, with activity migrating to the SW over time. Historical
eruptions, recorded since the 18th century, have originated from a
150-m-deep, 450-m-wide, steep-walled crater at the western part of the
summit and have consisted of explosive eruptions generally lasting a few
days to a few weeks.
Source: Earth Times http://www.earthtimes.org/articles/show/46509.html
Slamet Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-18=
TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m; All times are
local (= UTC - 5 hours)
IG reported that on 27 March, at 1716, an ash column from Tungurahua
rose to an altitude of 11 km (36,000 ft) a.s.l. An accompanying
pyroclastic flow traveled 1 km down the Mandur gorge on the NW flank. A
lahar traveled W down the Bilbao gorge and vibrated near-by structures.
On 28 March, ash plumes again rose to altitudes of 11 km (36,000 ft)
a.s.l. Ashfall was reported from areas downwind. Noises that resembled
rolling blocks down the flanks were reported. Hot steaming mudflows
traveled N, NW, and W. On 29 March, three explosions rattled windows in
areas as far away as 8 km. During 30 March-3 April, ash plumes,
occasionally accompanied by roaring noises and “cannon shots,” rose to
altitudes of 6-10.5 km (19,700-34,400 ft) a.s.l. and drifted mainly W
and NW. Incandescent material was ejected 300 m above the crater and
subsequently descended about 1 m down the flank on 31 March; similar
activity was observed at the summit during 1-2 April. Ashfall was
reported from areas about 8 km SW, N, and W.
Geologic Summary. The steep-sided Tungurahua stratovolcano towers more
than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador’s
capital city, and is one of Ecuador's most active volcanoes. Historical
eruptions have been restricted to the summit crater. They have been
accompanied by strong explosions and sometimes by pyroclastic flows and
lava flows that reached populated areas at the volcano's base. The last
major eruption took place from 1916 to 1918, although minor activity
continued until 1925. The latest eruption began in October 1999 and
prompted temporary evacuation of the town of Baños on the N side of the
volcano.
Source: Instituto Geofísico-Escuela Poltécnica Nacional
http://www.igepn.edu.ec/
Tungurahua Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08=
Ongoing Activity
KARANGETANG [Api Siau] Siau Island, Indonesia 2.47°N, 125.29°E; summit
elev. 1,784 m
According to a news article, eruption plumes from Karangetang rose to an
altitude of 1.9 km (6,000 ft) a.s.l. on 27 March. Pyroclastic flows may
have occurred the next day.
Geologic Summary. Karangetang (also known as Api Siau) lies at the
northern end of the island of Siau, N of Sulawesi. The 1,784-m-high
stratovolcano contains five summit craters along a N-S line. One of
Indonesia's most active volcanoes, Karangetang has had more than 40
recorded eruptions since 1675. Twentieth-century eruptions have included
frequent explosions, sometimes accompanied by pyroclastic flows and lahars.
Source: Jakarta Post
http://www.thejakartapost.com/detailgeneral.asp?fileid=20070328135533&irec=17
Karangetang Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0607-02=
KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m
Based on satellite imagery and information from the
Petropavlovsk-Kamchatsky Flight Information Region (FIR), the Tokyo VAAC
reported that an eruption plume from Karymsky rose to an altitude of 3
km (10,000 ft) a.s.l. on 31 March.
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: Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
Karymsky Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13=
KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m
During 28 March-3 April, lava from Kilauea continued to flow across a
lava delta into the ocean at the Kamokuna entry. Lava was not seen
entering the ocean at the East Lae'apuki entry. During 28-29 March, a
more than usual number of earthquakes were located near the Halema’uma’u
and Koko’olau craters and on the S flank. Incandescence was
intermittently visible from several breakouts on the Pulama pali and
from several vents in Pu'u 'O'o's crater. On 31 March, a major lava
breakout from the Campout flow caused trees to ignite on a near-by
kipuka (an “island” of vegetation) and produced small explosions from
trapped gas.
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 by
lava flows less than about 1,100 years old; 70% of the volcano's surface
is younger than 600 years. The latest Kilauea eruption began in January
1983 along the E rift zone. This long-term ongoing eruption from Pu`u
`O`o-Kupaianaha has produced lava flows that have traveled 11-12 km from
the vents to the sea, paving broad areas on the S flank of Kilauea and
adding new land beyond the former coastline.
Source: US Geological Survey Hawaiian Volcano Observatory
http://volcano.wr.usgs.gov/hvostatus.php
Kilauea information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-
KLIUCHEVSKOI Kamchatka Peninsula, Russia 56.06°N, 160.64°E; summit elev.
4,835 m
Based on observation and video data, lava from Kliuchevskoi flowed down
the NW flank on 29 March. On 31 March, lava bombs from Strombolian
activity were projected about 100-200 m above the crater. According to a
news article, lava flows are interacting with snow and ice and producing
vapor plumes.
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 have occurred during the
past 3,000 years, mostly on the NE and SE flanks of the conical volcano
between 500 m and 3,600 m elevation. 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 eruptions from flank craters.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) via the
Volcano Listserv http://www.volcano.si.edu/reports/volclist/index.htm,
RIA Novosti http://en.rian.ru/russia/20070329/62782184.html
Kliuchevskoi Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-26=
PITON DE LA FOURNAISE Réunion Island, Indian Ocean 21.23°S, 55.71°E;
summit elev. 2,631 m
OVPDLF reported that on 2 April lava fountains about 50 m high erupted
from a fissure at Piton de la Fournaise. The NW-SE-trending fissure was
located SW of Dolomieu crater and was about 1 km long.
Geologic Summary. The massive Piton de la Fournaise shield volcano on
the island of Réunion is one of the world's most active volcanoes. Most
historical eruptions have originated from the summit and flanks of
Dolomieu, a 400-m-high lava shield that has grown within the youngest of
three large calderas. This latter caldera is 8 km wide and is breached
to below sea level on the eastern side. More than 150 eruptions, most of
which have produced fluid basaltic lava flows within the caldera, have
been documented since the 17th century.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPDLF)
http://ovpf.univ-reunion.fr/
Piton de la Fournaise Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0303-02=
POPOCATÉPETL México 19.02°N, 98.62°W; summit elev. 5,426 m
Based on information from the Mexico City MWO, the Washington VAAC
reported that an ash plume from Popocatépetl rose to an altitude of 7.6
km (25,000 ft) a.s.l. and drifted NE on 1 April.
Geologic Summary. Popocatépetl, whose name is the Aztec word for smoking
mountain, towers to 5,426 m 70 km SE of Mexico City and is North
America's second-highest volcano. Frequent historical eruptions have
been recorded since the beginning of the Spanish colonial era. A small
eruption on 21 December 1994 ended five decades of quiescence. Since
1996 small lava domes have incrementally been constructed within the
summit crater and destroyed by explosive eruptions. Intermittent
small-to-moderate gas-and-ash eruptions have continued, occasionally
producing ashfall in neighboring towns and villages.
Source: Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html
Popocatépetl Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-09=
RABAUL New Britain Island, Papua New Guinea 4.271°S, 152.203°E; summit
elev. 688 m
RVO reported that during 26 March-1 April, Rabaul caldera's Tavurvur
cone emitted steam and steam-and-ash plumes that rose to 0.8 km (2,600
ft) a.s.l. and drifted E, N, and NW. Roaring noises occasionally
accompanied emissions. Incandescent material was ejected to at most 100
m above the lowest part of the vent during 26-30 March. Based on reports
from RVO and satellite imagery, the Darwin VAAC reported that ash plumes
rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted NE
during 1-2 April.
Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle
Peninsula at the NE end of New Britain forms a broad sheltered harbor.
The outer flanks of the 688-m-high asymmetrical pyroclastic shield
volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km
caldera is widely breached on the E, where its floor is flooded by
Blanche Bay. Two major Holocene caldera-forming eruptions at Rabaul took
place as recently as 3,500 and 1,400 years ago. Three small
stratovolcanoes lie outside the northern and NE caldera rims.
Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on
the caldera floor near the NE and western caldera walls. Several of
these, including Vulcan cone, which was formed during a large eruption
in 1878, have produced major explosive activity during historical time.
A powerful explosive eruption in 1994 occurred simultaneously from
Vulcan and Tavurvur volcanoes and forced the temporary abandonment of
Rabaul city.
Source: Steve Saunders, Rabaul Volcano Observatory,
Darwin Volcanic Ash Advisory Center
http://www.bom.gov.au/info/vaac/advisories.shtml
Rabaul Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-14=
SANTA MARÍA Guatemala 14.756°N, 91.552°W; summit elev. 3,772 m
INSIVUMEH reported that explosions from Santa María's Santiaguito lava
dome complex produced ash plumes that rose to an altitude of 5 km
(16,400 ft) a.s.l. on 29 March. Ashfall was reported near the
Observatory Vulcanológico de Santiaguito (OVSAN), about 5 km S. On 30
March, the Washington VAAC reported that diffuse ash plumes were visible
on satellite imagery drifting SW. On 2 April, INSIVUMEH reported that
ash plumes rose to 4.4 km (14,400 ft) a.s.l. and drifted SW.
Geologic Summary. Symmetrical, forest-covered Santa María 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/geofisica/boletin%20formato.htm,
Washington Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/messages.html
Santa María Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-03=
SHIVELUCH Kamchatka Peninsula, Russia 56.653°N, 161.360°E; summit elev.
3,283 m
An explosive event at Shiveluch on 29 March produced an ash plume that
rose to an estimated altitude of 9.8 km (32,000 ft) a.s.l. and drifted
NE. Based on reports from the Yelizovo Meteorological Watch Office and
satellite imagery, the Tokyo VAAC reported that the plume reached an
altitude of 11.9 km (39,000 ft) a.s.l. The next day, an explosive event
that lasted about 6 minutes produced a plume to altitudes of 10.1-12.2
km (33,000-40,000 ft) a.s.l., based on estimates from AVO, Tokyo VAAC,
and the Kamchatkan Branch of Geophysical Services. The plume drifted NE.
According to a news article, a mudflow covered an approximately
900-m-long section of road, about 20 km from Shiveluch on 31 March.
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 horseshoe-shaped 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. During the 1990s,
intermittent explosive eruptions took place from a new lava dome that
began growing in 1980. The largest historical eruptions from Shiveluch
occurred in 1854 and 1964.
Sources: Alaska Volcano Observatory http://www.avo.alaska.edu/,
Itar-Tass http://www.itar-tass.com/eng/level2.html?NewsID=11391328&PageNum=0
Shiveluch Information from the Global Volcanism Program
http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=1000-27=
SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev.
1,052 m
During 23 March-3 April, lava-dome growth at Soufrière Hills was reduced
or possibly paused. Small, intermittent pyroclastic flows occurred in
the Tar River Valley. Fumarolic activity was observed around the region
of a collapse scar at the head of Tyres Ghaut and was audible during
28-29 March. The Washington VAAC reported that a SW-drifting, diffuse
plume and a hotspot were visible on satellite imagery on 2 April.
Geologic Summary. The complex, dominantly andesitic Soufrière 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 east, was formed during an eruption about 4000 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 Soufrière 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 http://www.mvo.ms/
Soufrière Hills Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05=
ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m
Data from deformation-monitoring instruments and observations from a
remote camera showed that during 28 March-3 April, lava-dome growth at
Mount St. Helens continued. Seismicity persisted at low levels,
punctuated by M 1.5-2.5 and occasionally larger earthquakes. On 3 April,
a GPS unit on an active spine showed W-ward movement at a rate of about
30 cm/day.
Geologic Summary. Prior to 1980, Mount St. Helens formed a conical,
youthful volcano sometimes known as the Fuji-san of America. During the
1980 eruption the upper 400 m of the summit was removed by slope
failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially
filled by a lava dome. Mount St. Helens was formed during nine eruptive
periods beginning about 40-50,000 years ago, and has been the most
active volcano in the Cascade Range during the Holocene. The modern
edifice was constructed during the last 2,200 years, when the volcano
produced basaltic as well as andesitic and dacitic products from summit
and flank vents. Historical eruptions in the 19th century originated
from the Goat Rocks area on the N flank, and were witnessed by early
settlers.
Source: US Geological Survey Cascades Volcano Observatory
http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html
St. Helens Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05-
SUWANOSE-JIMA Ryukyu Islands, Japan 29.53°N, 129.72°E; summit elev. 799 m
Based on information from JMA, the Tokyo VAAC reported explosions from
Suwanose-jima on 30 March and 2 April. Ash was not visible on satellite
imagery.
Geologic Summary. The 8-km-long, spindle-shaped island of Suwanose-jima
in the northern Ryukyu Islands consists of an andesitic stratovolcano
with two historically active summit craters. Only about 50 persons live
on the sparsely populated island. The summit of the volcano is truncated
by a large breached crater extending to the sea on the E flank that was
formed by edifice collapse. Suwanose-jima, one of Japan’s most
frequently active volcanoes, was in a state of intermittent strombolian
activity from On-take, the NE summit crater, that began in 1949 and
lasted nearly a half century. The largest historical eruption took place
in 1813-14, when thick scoria deposits blanketed residential areas,
after which the island was uninhabited for around 70 years. The SW
crater produced lava flows that reached the western coast in 1813, and
lava flows reached the eastern coast of the island in 1884.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
Suwanose-jima Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=0802-03=
UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m
Based on pilot reports, the Buenos Aires VAAC reported that an ash cloud
from Ubinas rose to 5.5-6.1 km (18,000-20,000 ft) a.s.l. on 30 March and
drifted E. According to a news article, local residents observed
rockfalls and reported ashfall. A scientist from the Geological, Mining,
and Metallurgic Institute (INGEMMET) reported that the eruption was the
largest in a two-week period characterized by an increased rate of
explosions. A diffuse ash plume was visible on satellite imagery on 3
April drifting NE.
Geologic Summary. A small, 1.2-km-wide caldera that cuts the top of
Ubinas, Peru's most active volcano, gives it a truncated appearance.
Ubinas is the northernmost of three young volcanoes located along a
regional structural lineament about 50 km behind the main volcanic front
of Peru. The upper slopes of the stratovolcano, composed primarily of
Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The
steep-walled, 150-m-deep summit caldera contains an ash cone with a
500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche
deposits from the collapse of the SE flank of Ubinas extend 10 km from
the volcano. Widespread plinian pumice-fall deposits from Ubinas include
some of Holocene age. Holocene lava flows are visible on the volcano's
flanks, but historical activity, documented since the 16th century, has
consisted of intermittent minor explosive eruptions.
Sources: Buenos Aires Volcanic Ash Advisory Center (VAAC)
http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html,
Living in Peru
http://www.livinginperu.com/news-3509-peru-volcanic-explosion-causes-panic-peru
Ubinas Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02=
**+++++++++++++++++++++++++++++++++++++**
**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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