Volcano Digest - 12 Oct 2018 to 17 Oct 2018 (#2018-106)

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Topics of the day:

  1. Smithsonian / USGS Weekly Volcanic Activity Report 10-16 October 2018

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Date:    Wed, 17 Oct 2018 12:45:56 -0700
From:    Sean Peters <speter24@xxxxxxx>
Subject: Smithsonian / USGS Weekly Volcanic Activity Report 10-16 October 2018

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

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

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





New Activity/Unrest: Cuicocha, Ecuador  | Gamalama, Halmahera (Indonesia)
| Piton de la Fournaise, Reunion Island (France)  | Sangeang Api,
Indonesia  | Sarychev Peak, Matua Island (Russia)  | Semisopochnoi, United
States  | Soputan, Sulawesi (Indonesia)  | Ulawun, New Britain (Papua New
Guinea)



Ongoing Activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  |
Ebeko, Paramushir Island (Russia)  | Fuego, Guatemala  | Kadovar, Papua New
Guinea  | Manam, Papua New Guinea  | Merapi, Central Java (Indonesia)  |
Pacaya, Guatemala  | Sabancaya, Peru  | 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





Cuicocha  | Ecuador  | 0.308°N, 78.364°W  | Summit elev. 3246 m



IG reported that, after an earthquake swarm consisting of 62
volcano-tectonic events during 2-3 October, seismicity at Cuicocha returned
to background levels on 4 October. Carbon dioxide levels were normal, and
deformation data did not show any anomalies.



Geologic Summary. The scenic lake-filled Cuicocha caldera is located at the
southern foot of the sharp-peaked Pleistocene Cotacachi stratovolcano about
100 km N of Quito. Both Cotacachi and Cuicocha were constructed along the
Otavalo-Umpalá fracture zone. Eruptive activity began about 4500 years ago
and continued until about 1300 years ago. The 3-km-wide, steep-walled
caldera was created during a major explosive eruption about 3100 years ago
that produced nearly 5 km3 of pyroclastic-flow and fall deposits. Four
intra-caldera lava domes form two steep-sided forested islands in the
148-m-deep lake. A pre-caldera lava dome is situated on the outer E side of
the caldera. Pyroclastic-flow deposits cover wide areas around the
low-rimmed caldera, primarily to the east. Gas emission continues from
several locations in the caldera lake.



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





Gamalama  | Halmahera (Indonesia)  | 0.8°N, 127.33°E  | Summit elev. 1715 m



On 10 October PVMBG reported only gas emissions (mostly water vapor) from
Gamalama; the Aviation Color Code was lowered to Yellow. The Alert Level
remained at 2 (on a scale of 1-4); visitors and residents were warned not
to approach the crater within a 1.5-km radius.



Geologic Summary. Gamalama is a near-conical stratovolcano that comprises
the entire island of Ternate off the western coast of Halmahera, and is one
of Indonesia's most active volcanoes. The island was a major regional
center in the Portuguese and Dutch spice trade for several centuries, which
contributed to the thorough documentation of Gamalama's historical
activity. Three cones, progressively younger to the north, form the summit.
Several maars and vents define a rift zone, parallel to the Halmahera
island arc, that cuts the volcano. Eruptions, recorded frequently since the
16th century, typically originated from the summit craters, although flank
eruptions have occurred in 1763, 1770, 1775, and 1962-63.



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





Piton de la Fournaise  | Reunion Island (France)  | 21.244°S, 55.708°E  |
Summit elev. 2632 m



OVPF reported that the eruption at Piton de la Fournaise continued during
10-16 October, though webcam images indicated that the lava-flow front had
not significantly progressed since 8 October. The lava lake in the cone was
at a low level. Strong gas emissions rose from the main vent as well as
from the lava tube, just downstream from the vent.



Geologic Summary. The massive Piton de la Fournaise basaltic shield volcano
on the French island of Réunion in the western Indian Ocean is one of the
world's most active volcanoes. Much of its more than 530,000-year history
overlapped with eruptions of the deeply dissected Piton des Neiges shield
volcano to the NW. Three calderas formed at about 250,000, 65,000, and less
than 5000 years ago by progressive eastward slumping of the volcano.
Numerous pyroclastic cones dot the floor of the calderas and their outer
flanks. Most historical eruptions have originated from the summit and
flanks of Dolomieu, a 400-m-high lava shield that has grown within the
youngest caldera, which is 8 km wide and breached to below sea level on the
eastern side. More than 150 eruptions, most of which have produced fluid
basaltic lava flows, have occurred since the 17th century. Only six
eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from
fissures on the outer flanks of the caldera. The Piton de la Fournaise
Volcano Observatory, one of several operated by the Institut de Physique du
Globe de Paris, monitors this very active volcano.



Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)
http://www.ipgp.fr/





Sangeang Api  | Indonesia  | 8.2°S, 119.07°E  | Summit elev. 1949 m



Based on a VONA from PVMBG an ash emission from Sangeang Api was generated
at 1338 on 15 October; it rose 250 m above the summit and drifted SW, W,
and NW. The VONA noted that the ash emission possibly rose higher than what
a ground observer had estimated. Seismic data was dominated by signals
indicating emissions as well as local tectonic earthquakes. The Aviation
Color Code was changed from Yellow to Orange.



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, 1949-m-high Doro Api and 1795-m-high 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: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM) http://vsi.esdm.go.id/





Sarychev Peak  | Matua Island (Russia)  | 48.092°N, 153.2°E  | Summit elev.
1496 m



Based on Tokyo VAAC data and satellite images, KVERT reported that at 1330
on 10 October an ash plume from Sarychev Peak rose to 1.7-2 km (5,600-6,600
ft) a.s.l. and drifted 95 km E. SVERT reported that on 15 October an ash
plume rose 2.1 km (7,000 ft) a.s.l. and drifted 65-70 km E. The Aviation
Color Code remained at Orange.



Geologic Summary. Sarychev Peak, one of the most active volcanoes of the
Kuril Islands, occupies the NW end of Matua Island in the central Kuriles.
The andesitic central cone was constructed within a 3-3.5-km-wide caldera,
whose rim is exposed only on the SW side. A dramatic 250-m-wide, very
steep-walled crater with a jagged rim caps the volcano. The substantially
higher SE rim forms the 1496 m high point of the island. Fresh-looking lava
flows, prior to activity in 2009, had descended in all directions, often
forming capes along the coast. Much of the lower-angle outer flanks of the
volcano are overlain by pyroclastic-flow deposits. Eruptions have been
recorded since the 1760s and include both quiet lava effusion and violent
explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows
that reached the sea.



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

Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/





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



On 11 October AVO reported that satellite data of Semisopochnoi indicated
partial erosion of a tephra cone in the crater of Cerberus’s N cone. A
crater lake about 90 m in diameter filled the vent. The data also suggested
that the vent had not erupted since 1 October. Seismicity remained elevated
and above background levels. The next day AVO lowered the Aviation Color
Code to Yellow and the Volcano Alert Level to Advisory, noting the recent
satellite data results and lack of tremor recorded during the previous week.



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/





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



On 16 October PVMBG issued a VONA noting only white emissions at Soputan;
the Aviation Color Code was lowered to Yellow.



Geologic Summary. The Soputan stratovolcano on the southern rim of the
Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of
Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano
rises to 1784 m and is located SW of Riendengan-Sempu, which some workers
have included with Soputan and Manimporok (3.5 km ESE) as a volcanic
complex. It was constructed at the southern end of a SSW-NNE trending line
of vents. During historical time the locus of eruptions has included both
the summit crater and Aeseput, a prominent NE-flank vent that formed in
1906 and was the source of intermittent major lava flows until 1924.



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





Ulawun  | New Britain (Papua New Guinea)  | 5.05°S, 151.33°E  | Summit
elev. 2334 m



RVO reported that during 1-12 October white and sometimes light gray
emissions rose from Ulawun’s summit crater. Seismicity was low.



Geologic Summary. The symmetrical basaltic-to-andesitic Ulawun
stratovolcano is the highest volcano of the Bismarck arc, and one of Papua
New Guinea's most frequently active. The volcano, also known as the Father,
rises above the north coast of the island of New Britain across a low
saddle NE of Bamus volcano, the South Son. The upper 1000 m is unvegetated.
A prominent E-W escarpment on the south may be the result of large-scale
slumping. Satellitic cones occupy the NW and E flanks. A steep-walled
valley cuts the NW side, and a flank lava-flow complex lies to the south of
this valley. Historical eruptions date back to the beginning of the 18th
century. Twentieth-century eruptions were mildly explosive until 1967, but
after 1970 several larger eruptions produced lava flows and basaltic
pyroclastic flows, greatly modifying the summit crater.



Source: Rabaul Volcano Observatory (RVO)





Ongoing Activity





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



JMA reported occasional, very small events at Minamidake crater (at Aira
Caldera’s Sakurajima volcano) during 9-15 October. Sulfur dioxide emissions
decreased from 3,400 tons/day on 4 October to 600 tons/day on 10 October.
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 data, wind model data, and notices from PVMBG, the
Darwin VAAC reported that during 10-12 October ash plumes from Dukono rose
to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted W and SW.



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 5-12 October that sent ash plumes to 4.5
km (14,800 ft) a.s.l. Satellite images showed ash plumes drifting about 125
km SE on 5 and 8 October, and a thermal anomaly over the volcano on 8
October. 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 and CONRED reported that on 12 October a new phase of activity
began at Fuego, characterized by lava fountains rising as high as 400 m
above the crater rim, avalanches of incandescent material down the W and
SSW flanks, increased rumbling, and a lava flow traveling 1 km down the
Santa Teresa (W) drainage. Very frequent explosions generated ash plumes
that rose 850 m and drifted 12 km S and SE. On 13 October a steaming lahar
descended the Ceniza (SSW) drainage, carrying blocks up to 2 m in diameter,
and branches and tree trunks. During 13-16 October explosions (8-18 per
hour) produced ash plumes that rose almost 1 km and drifted 8-12 km S, SW,
and W. Ashfall was reported in areas downwind including Sangre de Cristo (8
km WSW), Finca Palo Verde, and Panimaché I and II (8 km SW). Incandescent
material was ejected 150-200 m high, causing avalanches of material within
the crater, though some of the avalanches traveled long distances, reaching
vegetated areas. The lava flow on the W flank was still visible but by 14
October no longer active.



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



Based on satellite data and wind model data, the Darwin VAAC reported that
during 10-12 October ash plumes from Kadovar rose to an altitude of 2.4 km
(8,000 ft) a.s.l. and drifted NW and W.



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





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



RVO reported that during 2-12 October brown, gray-brown, and dark gray ash
emissions rose as high as 1 km above Manam’s Southern Crater rim and
drifted NW. Main Crater produced occasional white emissions, though on 2
October plumes were gray-brown and contained ash. Bluish vapor was noted
during 3-4 October.



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



Source: Rabaul Volcano Observatory (RVO)





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



PVMBG reported that during 5-11 October the lava dome in Merapi’s summit
crater grew slowly at a rate of 3,100 cubic meters per day, though faster
than the previous week. By 11 October the volume of the dome was an
estimated 160,000 cubic meters. White emissions of variable density rose a
maximum of 75 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/





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



INSIVUMEH reported that during 11-15 October Strombolian explosions at
Pacaya’s Mackenney Crater ejected material as high as 25 m above the crater
rim, and gas plumes rose 200-700 m. A lava flow that first emerged on 11
October traveled NW towards Cerro Chino, and by 15 October was 250 m long.



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



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





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 explosions at Sabancaya
averaged 17 per day during 8-14 October. Hybrid earthquakes were infrequent
and of low magnitude. Gas-and-ash plumes rose as high as 2.5 km above the
crater rim and drifted 30 km NE, E, SE, and SW. The MIROVA system detected
six thermal anomalies, and on 14 October the sulfur dioxide gas flux was
high at 3,132 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/





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 data during 8-10 October; weather clouds prevented views on the
other days during 5-12 October. 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 most days during 10-16 October intermittent,
passive gas-and-ash emissions at Turrialba rose as high as 1 km above the
crater rim. The emissions drifted W, SW, S, and NE. There were also some
explosive events; an energetic explosion was recorded at 1712 on 14
October, though cloudy weather prevented estimates of a plume height.



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 at Veniaminof continued during 10-16
October, as evidenced by elevated surface temperatures in satellite data,
and low-level continuous tremor. Satellite data indicated that the E part
of the S-flank flow field remained active. The Aviation Color Code remained
at Orange and the Volcano Alert Level remained at Watch.



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 - 12 Oct 2018 to 17 Oct 2018 (#2018-106)
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