Smithsonian / USGS Weekly Volcanic Activity Report 29 September-5 October 2021

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


Smithsonian / USGS Weekly Volcanic Activity Report
29 September-5 October 2021

Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx<mailto:kuhns@xxxxxx
>)
URL:
https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNQbKXRMM$


New Activity/Unrest: Kilauea, Hawaiian Islands (USA)  | La Palma, Spain  |
Nyiragongo, DR Congo  | Vulcano, Aeolian Islands (Italy)

Ongoing Activity: Aira, Kyushu (Japan)  | Great Sitkin, Andreanof Islands
(USA)  | Karymsky, Eastern Kamchatka (Russia)  | Katmai, United States  |
Klyuchevskoy, Central Kamchatka (Russia)  | Krysuvik-Trolladyngja, Iceland
| Langila, New Britain (Papua New Guinea)  | Lewotolok, Lembata Island
(Indonesia)  | Merapi, Central Java (Indonesia)  | Pavlof, United States  |
Reventador, Ecuador  | Sangay, Ecuador  | Semisopochnoi, Aleutian Islands
(USA)  | Sheveluch, Central Kamchatka (Russia)  | Suwanosejima, Ryukyu
Islands (Japan)  | Taal, Luzon (Philippines)  | Telica, Nicaragua  | Yasur,
Vanuatu


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


Kilauea  | Hawaiian Islands (USA)  | 19.421°N, 155.287°W  | Summit elev.
1222 m

Seismicity abruptly increased below Kilauea's summit at about 1400 on 29
September. Around 30 minutes later the earthquakes became more intense,
frequent, and shallower, and deformation patterns rapidly changed. The data
suggested an upward movement of magma that prompted HVO to raise the
Aviation Color Code to Orange and the Volcano Alert Level to Watch at 1509.
A new eruption was identified at 1521 when incandescence from Halema`uma`u
Crater became visible in webcam views; HVO raised the Aviation Color Code
to Red and the Volcano Alert Level to Warning. Fissures opened along the
bottom of Halema`uma`u Crater floor and produced lava fountains and flows.
A photo taken at 1615 showed a large plume comprised of steam, carbon
dioxide, and sulfur dioxide rising from the fissures. Measurements just
after the eruption started showed sulfur dioxide emissions of around 85,000
tonnes/day. At about 1640 another fissure with several vents opened on the
inner W wall of the crater and produced low lava fountains and flows that
descended to the crater floor. The vent expanded by 1709. Lava from both
fissures pooled on the solidified lava lake surface and quickly began to
overturn and create a lava lake. Tephra was deposited in areas SW of the
crater and collected by HVO scientists for analysis.

The tallest lava fountain was near the S end of the lava lake and rose
20-25 m during the night of 29-30 September. During a helicopter overflight
around 0730 on 30 September scientists determined that the lake was about
980 m E-W and 710 m N-S, covering an estimated 52 hectares. The W wall vent
was visible, and several fountains were rising from the fissure in the
central part of the lake. Sulfur dioxide emission rates remained high,
estimated at around 20,000 tonnes/day. Overnight during 30 September-1
October fountains rose as high as 15 m at the dominant vent in the W wall.
Less vigorous fountaining persisted at other vents, though fewer were
active. The lake had risen 24 m by the morning of 1 October, adding 4 m in
the past day. Cooled and crusted parts of the lake's surface overturned, or
"foundered." Sulfur dioxide emission rates remained high, estimated at
around 12,900 tonnes per day.

The lake had risen another 2 m by the morning of 2 October; fountains were
7 m tall at the main W wall vent and 1-2 m at the southern vents. Fountains
occasionally rose as high as 50-60 m in bursts. Pumice, Pele?s hair, and
fragments of volcanic glass were deposited downwind. The sulfur dioxide
emission rate on 3 October was again high at 14,750 tonnes/day. The W vent
was again the most vigorous during 3-4 October with sustained lava
fountains to 10-15 m with occasional bursts up to 20 m. The lake rose 3 m,
past the base of the W vent where a 12-m-high spatter cone had formed, and
continued to founder in spots. Lava fountains rose 5-10 m from the vents in
the S and central portions of the lake, including along a fissure 35-42 m
long, with occasional larger bursts. The lake was not level and generally
higher near the location of the vents; the W end was 1-2 m higher than the
E, and S end was about 1 m higher than the N. By 4 October ledges about 20
m wide separated the N and E parts of the active lava lake from the crater
wall and were lower than the lake surface; the N, E, and S margins of the
lake were perched about 3 m above the surrounding ledge. The sulfur dioxide
emission rate remained elevated but had decreased to 7,000-9,000
tonnes/day. HVO lowered the Aviation Color Code to Orange and the Volcano
Alert Level to Watch at 1652. On 5 October lava fountaining from the W vent
was unchanged while fountains from the other vents rose 1-5 m. The lake
rose 1 more meter.

Geologic Summary. Kilauea, which overlaps the E flank of the massive Mauna
Loa shield volcano, has been Hawaii's most active volcano during historical
time. Eruptions are prominent in Polynesian legends; written documentation
extending back to only 1820 records frequent summit and flank lava flow
eruptions that were interspersed with periods of long-term lava lake
activity that lasted until 1924 at Halemaumau crater, within the summit
caldera. The 3 x 5 km caldera was formed in several stages about 1500 years
ago and during the 18th century; eruptions have also originated from the
lengthy East and SW rift zones, which extend to the sea on both sides of
the volcano. About 90% of the surface of the basaltic shield volcano is
formed of lava flows less than about 1100 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 km2,
destroying nearly 200 houses and adding new coastline to the island.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
https://urldefense.com/v3/__https://volcanoes.usgs.gov/observatories/hvo/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNwnSHj1U$


La Palma  | Spain  | 28.57°N, 17.83°W  | Summit elev. 2426 m

The eruption at La Palma continued during 29 September-5 October,
characterized by Strombolian explosions, lava fountaining from multiple
vents, lava flows, and daily ash emissions. Seismicity continued to be
elevated with earthquakes located mainly 10-15 km deep (though some were
25-40 km deep) in the same area where the swarm first began on 11
September; dozens of events were felt by residents.

Within the first eight days of the eruption, 21-27 September, an estimated
50 million cubic meters of material had been erupted. Just before midnight
on 28 September the lava reached the ocean, producing a steam-and-gas
plume; within 45 minutes the lava created a 50-m-high delta. The sulfur
dioxide flux was as high as 16,760 tons per day. On 29 September the
PEVOLCA (Plan de Emergencias Volcánicas de Canarias) steering committee
restated that the 2.5 km and maritime exclusion zones around the vents and
ocean entry, respectively, remained in effect; residents were periodically
allowed to collect belongings and care for animals and crops. The lava
covered almost 4.8 square kilometers, burying or damaging 744 buildings.
There were 185 evacuees in a local hotel. Ash plumes continued to rise from
the active vents, and IGN noted a decrease in plume altitude to 3.5 km
(11,500 ft) a.s.l. on 29 September and then a rise to 5 km (16,400 ft)
a.s.l. the next day.

Lava continued flowing to the sea along the same path. The lava delta had
grown three times in size by 30 September to an estimated 0.17 square
kilometers; the furthest edge of the delta was 450 m from the coast, it had
spread laterally 600-800 m, and was as thick as 24 m. PEVOLCA lifted access
restrictions for residents of Tazacorte, San Borondón, Marina Alta, Marina
Baja, and La Condesa (nearly 4,000 people); they had previously been warned
to stay indoors to minimize coming into contact with potentially toxic gas
plumes generated from the ocean entry. Restrictions for other residents
living near the margins of the flows were also lifted.

Two vents opened about 600 m NW of the main cone on 1 October and within
two days had formed small cones. Lava from the vents traveled W and joined
the main flow field downslope. The lava delta had extended 540 m from the
coastline. Ash plumes rose to 3-5 km a.s.l. and drifted S on 2 October, and
sulfur dioxide emissions were 3,401 tons per day.

By 3 October an estimated 946 houses had been completely demolished and 128
had been partially damaged. The width of the flow field was a maximum of
1,250 m and lava tubes were identified in satellite images. The lava delta
had developed four lobes being fed by multiple flows and had an estimated
area of 0.32 square kilometers. In the afternoon the frequency and
intensity of explosive activity increased and bombs were ejected as far as
800 m. Lava fountains rose hundreds of meters and ash plumes rose as high
as 4.5 km (14,800 ft) a.s.l. The sulfur dioxide emission rate reached
16,000 tons per day. During 1900-1945 one of the new cones collapsed, which
allowed the inner lava lake to spill out, sending flows downslope carrying
blocks from the destroyed portion of the cone. Ash plumes rose as high as
4.5 km a.s.l. and explosions ejected bombs on 5 October according to a news
report. Some explosions produced dense black plumes that billowed as they
rose above the vent. The Alert Level remained at Red (the highest level on
a four-color scale) for affected communities.

Geologic Summary. The 47-km-long wedge-shaped island of La Palma, the
NW-most of the Canary Islands, is composed of two large volcanic centers.
The older northern one is cut by the massive steep-walled Caldera
Taburiente, one of several massive collapse scarps produced by edifice
failure to the SW. The younger Cumbre Vieja, the southern volcano, is one
of the most active in the Canaries. The elongated volcano dates back to
about 125,000 years ago and is oriented N-S. Eruptions during the past
7,000 years have formed abundant cinder cones and craters along the axis of
Cumbre Vieja, producing fissure-fed lava flows that descend steeply to the
sea. Eruptions recorded since the 15th century have produced mild explosive
activity and lava flows that damaged populated areas. The southern tip of
the island is mantled by a broad lava field emplaced during the 1677-1678
eruption. Lava flows also reached the sea in 1585, 1646, 1712, 1949, and
1971.

Sources: Instituto Volcanológico de Canarias (INVOLCAN)
https://urldefense.com/v3/__http://www.involcan.org/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNhREyvU0$
 ;
Instituto Geográfico Nacional (IGN)
https://urldefense.com/v3/__https://www.ign.es/web/ign/portal__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNTCufv1E$
 ;
EL PAÃ?S
https://urldefense.com/v3/__https://elpais.com/ciencia/2021-09-26/mapa-casa-a-casa-del-avance-del-volcan-de-la-palma-la-lava-alcanza-500-viviendas-y-amenaza-otras-1500.html__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNagvC8fk$
 ;
EL PAÃ?S
https://urldefense.com/v3/__https://elpais.com/videos/2021-09-29/video-la-lava-crea-una-nueva-plataforma-en-el-litoral-de-la-palma.html__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNAfFgwxE$
 ;
EL PAÃ?S
https://urldefense.com/v3/__https://elpais.com/ciencia/2021-09-30/no-es-un-rio-la-lava-puede-dispersarse-en-otras-direcciones-aunque-ahora-fluya-hacia-al-mar.html__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNaShFb30$
 ;
EL PAÃ?S
https://urldefense.com/v3/__http://www.112canarias.com/web/index.php/15-noticias/ultimasnoticas/566-el-frente-de-lava-se-situa-en-el-limite-entre-los-municipios-de-los-llanos-y-tazacorte-2__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNN17Aa68$
 ;
EL PAÃ?S
https://urldefense.com/v3/__https://elpais.com/sociedad/2021-10-04/fue-como-una-presa-que-se-rompe-la-lava-cubre-ya-413-hectareas-de-la-palma-y-alcanza-un-perimetro-de-36-kilometros.html__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNGDZXuHo$
 ;
Jorge Eduardo Romero Moyano (University of Manchester)
https://urldefense.com/v3/__https://www.researchgate.net/profile/Jorge-Romero-26__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNd53s1H4$
 ;
Gobierno de Canaries
https://urldefense.com/v3/__http://www.gobcan.es/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNQf7gjpM$
 ;
1-1-2 Canarias
https://urldefense.com/v3/__http://www.112canarias.com/web/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNMSSfI6Y$


Nyiragongo  | DR Congo  | 1.52°S, 29.25°E  | Summit elev. 3470 m

According to a news article the scientific director of GVO stated that lava
had returned to Nyiragongo's crater on 18 September. Notable thermal
anomalies were visible in Sentinel satellite images on 29 September and 4
October.

Geologic Summary. One of Africa's most notable volcanoes, Nyiragongo
contained a lava lake in its deep summit crater that was active for half a
century before draining catastrophically through its outer flanks in 1977.
The steep slopes of a stratovolcano contrast to the low profile of its
neighboring shield volcano, Nyamuragira. Benches in the steep-walled,
1.2-km-wide summit crater mark levels of former lava lakes, which have been
observed since the late-19th century. Two older stratovolcanoes, Baruta and
Shaheru, are partially overlapped by Nyiragongo on the north and south.
About 100 parasitic cones are located primarily along radial fissures south
of Shaheru, east of the summit, and along a NE-SW zone extending as far as
Lake Kivu. Many cones are buried by voluminous lava flows that extend long
distances down the flanks, which is characterized by the eruption of
foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities,
as did lava flows that inundated portions of the major city of Goma in
January 2002.

Sources: Observatoire Volcanologique de Goma (OVG)
https://urldefense.com/v3/__http://observatoirevolcanologiquedegoma.org/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNXWjYTp0$
 ;
Agence France-Presse (AFP)
https://urldefense.com/v3/__https://www.thejakartapost.com/life/2021/09/27/new-lava-lake-lets-dr-congo-volcano-breathe-experts-say.html__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNhwDyoII$


Vulcano  | Aeolian Islands (Italy)  | 38.404°N, 14.962°E  | Summit elev.
500 m

INGV reported that hydrothermal activity at Vulcano increased in July, and
notably more in September. Specifically, temperatures of the fumaroles on
the crater rim and on the inner flank had increased along with the amounts
of carbon dioxide and sulfur dioxide in the emissions. The highest
temperature of 340 degrees Celsius was along the rim. The temperature and
salinity of groundwater measured near the base of La Fossa cone were both
elevated, and outgassing from ground sites was noted. On 13 September the
seismic network detected a significant increase in microseismcity linked to
hydrothermal processes. Additionally, very-long-period events were also
recorded for the first time in 15 years when instrumentation able to detect
the signals was installed. Deformation on the N side of the cone was first
identified in mid-August and totaled 1 cm of uplift by mid-September. The
report stated that new seismic stations and instruments to measure carbon
dioxide emissions had been added to the monitoring network, and a thermal
camera pointing at the fumarolic field was planned. The Dipartimento della
Protezione Civile raised the Alert Level to Yellow (the second lowest level
on a four-color scale) on 1 October.

Geologic Summary. The word volcano is derived from Vulcano stratovolcano in
Italy's Aeolian Islands. Vulcano was constructed during six stages over the
past 136,000 years. Two overlapping calderas, the 2.5-km-wide Caldera del
Piano on the SE and the 4-km-wide Caldera della Fossa on the NW, were
formed at about 100,000 and 24,000-15,000 years ago, respectively, and
volcanism has migrated north over time. La Fossa cone, active throughout
the Holocene and the location of most historical eruptions, occupies the
3-km-wide Caldera della Fossa at the NW end of the elongated 3 x 7 km
island. The Vulcanello lava platform is a low, roughly circular peninsula
on the northern tip of Vulcano that was formed as an island beginning more
than 2,000 years ago and was connected to the main island in about 1550 CE.
Vulcanello is capped by three pyroclastic cones and was active
intermittently until the 16th century. The latest eruption from Vulcano
consisted of explosive activity from the Fossa cone from 1898 to 1900.

Sources: Sezione di Catania - Osservatorio Etneo (INGV)
https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNwDWXnB8$
 ;
Dipartimento della Protezione Civile
https://urldefense.com/v3/__https://www.protezionecivile.gov.it/it/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqN8tpP3v8$


Ongoing Activity


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

JMA reported that incandescence from Minamidake Crater (at Aira Caldera's
Sakurajima volcano) was visible at night during 27 September-4 October. The
trend of inflation that was first detected on 13 September continued. The
sulfur dioxide emission rate was 1,500 tons per day on 28 September. A very
small eruptive event occurred on 3 October. The Alert Level remained at 3
(on a 5-level scale), and residents were warned to stay 2 km away from the
crater.

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)
https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqN_NpHYWE$


Great Sitkin  | Andreanof Islands (USA)  | 52.076°N, 176.13°W  | Summit
elev. 1740 m

AVO reported that lava effusion continued at Great Sitkin during 29
September-5 October. Seismicity remained elevated and was characterized by
small earthquakes consistent with lava effusion. Elevated surface
temperatures were detected in satellite images. By 3 October the dome had
grown to 1,200 m E-W and 1,000 m N-S. Lava flows that continued to advance
down the S and SW flanks were about 300-350 m long. The SW lobe was
descending two drainages and produced hot avalanches that traveled 450 m
downslope on top of a snow field. The Aviation Color Code and the Volcano
Alert Level remained at Orange and Watch, respectively.

Geologic Summary. The Great Sitkin volcano forms much of the northern side
of Great Sitkin Island. A younger parasitic volcano capped by a small, 0.8
x 1.2 km ice-filled summit caldera was constructed within a large
late-Pleistocene or early Holocene scarp formed by massive edifice failure
that truncated an ancestral volcano and produced a submarine debris
avalanche. Deposits from this and an older debris avalanche from a source
to the south cover a broad area of the ocean floor north of the volcano.
The summit lies along the eastern rim of the younger collapse scarp.
Deposits from an earlier caldera-forming eruption of unknown age cover the
flanks of the island to a depth up to 6 m. The small younger caldera was
partially filled by lava domes emplaced in 1945 and 1974, and five small
older flank lava domes, two of which lie on the coastline, were constructed
along northwest- and NNW-trending lines. Hot springs, mud pots, and
fumaroles occur near the head of Big Fox Creek, south of the volcano.
Historical eruptions have been recorded since the late-19th century.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNR7b89pw$


Karymsky  | Eastern Kamchatka (Russia)  | 54.049°N, 159.443°E  | Summit
elev. 1513 m

KVERT reported that a thermal anomaly over Karymsky was identified in
satellite images during 24-28 September. Ash plumes rose as high as 4.6 km
(15,100 ft) a.s.l. and drifted 100 km E, SE, and SW during 24-26 September.
The Aviation Color Code remained at Orange (the second highest level on a
four-color scale).

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 during the early Holocene. The caldera cuts
the south side of the Pleistocene Dvor volcano and is located outside the
north margin of the large mid-Pleistocene Polovinka caldera, which contains
the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding
Karymsky eruptions originated beneath Akademia Nauk caldera, located
immediately south. The caldera enclosing Karymsky formed about 7600-7700
radiocarbon years ago; construction of the stratovolcano began about 2000
years later. The latest eruptive period began about 500 years ago,
following a 2300-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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNYuQRB_4$


Katmai  | United States  | 58.28°N, 154.963°W  | Summit elev. 2047 m

AVO reported that beginning at 0400 on 2 October strong winds in the
vicinity of Katmai and the Valley of Ten Thousand Smokes blew
unconsolidated ash SE towards Kodiak Island at an altitude up to 1.8 km
(6,000 ft) a.s.l. The ash was originally deposited during the Novarupta
eruption in 1912. The Volcano Alert Level remained at Normal and the
Aviation Color Code remained at Green.

Geologic Summary. Prior to 1912, Mount Katmai was a compound stratovolcano
with four NE-SW-trending summits, most of which were truncated by caldera
collapse in that year. Two or more large explosive eruptions took place
from Mount Katmai during the late Pleistocene. Most of the two overlapping
pre-1912 Katmai volcanoes are Pleistocene in age, but Holocene lava flows
from a flank vent descend the SE flank of the SW stratovolcano into the
Katmai River canyon. Katmai was initially considered to be the source of
the Valley of Ten Thousand Smokes ash flow in 1912. However, the 3 x 4 km
wide caldera of 1912 is now known to have formed as a result of the
voluminous eruption at nearby Novarupta volcano. The steep walled young
caldera has a jagged rim that rises 500-1000 m above the caldera floor and
contains a 250-m-deep, still-rising lake. Lake waters have covered a small
post-collapse lava dome (Horseshoe Island) that was seen on the caldera
floor at the time of the initial ascent to the caldera rim in 1916.
Post-1912 glaciers have formed on a bench within Katmai caldera.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNR7b89pw$


Klyuchevskoy  | Central Kamchatka (Russia)  | 56.056°N, 160.642°E  | Summit
elev. 4754 m

On 29 September strong winds resuspended unconsolidated ash from
Klyuchevskoy's flanks causing KVERT to raise the Aviation Color Code to
Orange (the second highest level on a four-color scale). Conditions were
quiet the next day; KVERT lowered the Aviation Color Code back to Green.

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)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNYuQRB_4$


Krysuvik-Trolladyngja  | Iceland  | 63.917°N, 22.067°W  | Summit elev. 360 m

The Institute of Earth Sciences reported that lava effusion at
Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the
Reykjanes Peninsula, likely ceased during the evening of 18 September. The
area of the flow field was about 4.85 square kilometers, and the total
volume erupted was 150 million cubic meters, based on 30 September
measurements. Parts of lava flows thickened in areas to the S of
Geldingadalur and in Nàtthagi valley, and deflated in areas N of
Geldingadalur. Points of incandescence were visible at night, at least
through 4 October, likely from lava flows that continued to advance
downslope.

A seismic swarm in an area SW of Keilir (about 10 km NE of the fifth vent),
at the N end of the dike intrusion, began on 27 September. According to
news reports, over 6,000 earthquakes at depths of 5-6 km had been recorded
by 4 October with at least 12 of them over M 3; the largest event was a M
3.8. Some of the larger events were felt in the capital. The seismicity was
similar to patterns recorded before the beginning of the eruption to the
SW. IMO stated that more data was needed to characterize the data as either
indicative of magma movement or due to tectonic stress. The Aviation Color
Code remained at Orange due to the lack of ash and tephra emissions, though
IMO warned of the potential for lapilli and scoria fallout within a 650 m
radius of the active vent. Authorities also warned of gas emission hazards.

Geologic Summary. The Krýsuvík-Trölladyngja volcanic system is described by
the Catalogue of Icelandic Volcanoes as an approximately 50-km-long
composite fissure swarm trending about N38°E, including a 30-km-long swarm
of fissures, with no central volcano. It is one of the volcanic systems
arranged en-echelon along the Reykjanes Peninsula west of Kleifarvatn lake.
The Fagradalsfjall and Krýsuvík fissure swarms are considered splits or
secondary swarms of the Krýsuvík-Trölladyngja volcanic system. Small shield
volcanoes have produced a large portion of the erupted volume within the
system. Several eruptions have taken place since the settlement of Iceland,
including the eruption of a large basaltic lava flow from the Ogmundargigar
crater row around the 12th century. The latest eruption, identified through
tephrochronology, took place during the 14th century.

Sources: Icelandic Meteorological Office (IMO)
https://urldefense.com/v3/__http://en.vedur.is/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNje0S7sc$
 ;
Icelandic National Broadcasting Service (RUV)
https://urldefense.com/v3/__https://www.ruv.is/frett/2021/10/03/vogar-skjalfa-en-grindavik-ekki__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNIQzonWo$
 ;
Icelandic National Broadcasting Service (RUV)
https://urldefense.com/v3/__https://www.ruv.is/frett/2021/10/04/a-thousand-quakes-but-no-erupting-lava?term=Keili__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNUgOyKX4$
 ;
Almannavarnadeild ríkislögreglustjóra (National Commissioner of the
Icelandic Police and Department of Civil Protection and Emergency
Management)
https://urldefense.com/v3/__https://www.almannavarnir.is/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNmrx7ilg$


Langila  | New Britain (Papua New Guinea)  | 5.525°S, 148.42°E  | Summit
elev. 1330 m

The Darwin VAAC reported that a discrete ash plume from Langila rose to 1.8
km (6,000 ft) a.s.l. on 3 October and drifted S. A thermal anomaly was
visible afterward. On 4 October an ash plume again rose to 1.8 km a.s.l.
and drifted S.

Geologic Summary. Langila, one of the most active volcanoes of New Britain,
consists of a group of four small overlapping composite basaltic-andesitic
cones on the lower E flank of the extinct Talawe volcano in the Cape
Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is
breached widely to the SE; Langila was constructed NE of the breached
crater of Talawe. An extensive lava field reaches the coast on the N and NE
sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes
accompanied by lava flows, have been recorded since the 19th century from
three active craters at the summit. The youngest and smallest crater (no. 3
crater) was formed in 1960 and has a diameter of 150 m.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)
https://urldefense.com/v3/__http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNg3OGZEo$


Lewotolok  | Lembata Island (Indonesia)  | 8.274°S, 123.508°E  | Summit
elev. 1431 m

PVMBG reported that the eruption at Lewotolok continued during 28
September-4 October. White-and-gray plumes rose as high as 800 m above the
summit and drifted NW, W, and SW. Rumbling sounds were reported almost
daily. During 30 September-1 October and 3-4 October incandescent material
was ejected as far as 700 m away from the vent in multiple directions. The
Alert Level remained at 3 (on a scale of 1-4) and the public was warned to
stay 3 km away from the summit crater.

Geologic Summary. The Lewotolok (or Lewotolo) stratovolcano occupies the
eastern end of an elongated peninsula extending north into the Flores Sea,
connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is
symmetrical when viewed from the north and east. A small cone with a
130-m-wide crater constructed at the SE side of a larger crater forms the
volcano's high point. Many lava flows have reached the coastline. Eruptions
recorded since 1660 have consisted of explosive activity from the summit
crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known
as CVGHM)
https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNavyfZgY$


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

BPPTKG reported minor morphological changes to Merapi's SW lava dome,
located just below the SW rim and in the summit crater, and no changes to
the summit crater dome during 24-30 September. The SW dome grew 1 m taller
and had an estimated volume of 1.63 million cubic meters; the summit lava
dome had an estimated volume of 2.85 million cubic meters. As many as 67
lava avalanches traveled a maximum of 1.8 km SW. The Alert Level remained
at 3 (on a scale of 1-4), and the public was warned to stay 3-5 km away
from the summit based on location.

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 2,000 years ago, leaving a large arcuate scarp cutting the
eroded older Batulawang volcano. Subsequent growth of the steep-sided Young
Merapi edifice, its upper part unvegetated due to frequent 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.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi
(BPPTKG)
https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNeVXKmnk$


Pavlof  | United States  | 55.417°N, 161.894°W  | Summit elev. 2493 m

AVO reported that seismicity at Pavlof remained elevated during 29
September-5 October. No explosions were recorded most days by the seismic
and infrasound networks, and no eruptive activity was observed in mostly
cloudy webcam and satellite images. On 3 October webcam images showed that
recent ash deposits on the flanks had been covered by fresh snow; later
that night either new ash deposits were visible in webcam images or older
deposits were revealed due to snowmelt. Weakly elevated surface
temperatures were identified in satellite images. At least two minor
explosions were recorded during 4-5 October and minor emissions likely
comprised of steam and sulfur dioxide were visible in morning webcam images
on 5 October. The Volcano Alert Level and Aviation Color Code remained at
Watch and Orange, respectively.

Geologic Summary. The most active volcano of the Aleutian arc, Pavlof is a
2519-m-high Holocene stratovolcano that was constructed along a line of
vents extending NE from the Emmons Lake caldera. Pavlof and its twin
volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of
symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and
Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW
flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof
Sister, Pavlof has been frequently active in historical time, typically
producing Strombolian to Vulcanian explosive eruptions from the summit
vents and occasional lava flows. The active vents lie near the summit on
the north and east sides. The largest historical eruption took place in
1911, at the end of a 5-year-long eruptive episode, when a fissure opened
on the N flank, ejecting large blocks and issuing lava flows.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNR7b89pw$


Reventador  | Ecuador  | 0.077°S, 77.656°W  | Summit elev. 3562 m

IG reported that a high level of activity continued to be recorded at
Reventador during 29 September-3 October; cloudy weather conditions
sometimes prevented webcam and satellite views. Gas-and-ash plumes, often
observed multiple times a day with the webcam or reported by the Washington
VAAC, rose as high as 1 km above the summit crater and drifted mainly W and
NW. Crater incandescence was often observed at night along with
incandescent blocks that rolled as far as 800 m down the flanks.

Geologic Summary. Reventador is the most frequently active of a chain of
Ecuadorian volcanoes in the Cordillera Real, well east of the principal
volcanic axis. The forested, dominantly andesitic Volcán El Reventador
stratovolcano rises to 3562 m above the jungles of the western Amazon
basin. A 4-km-wide caldera widely breached to the east was formed by
edifice collapse and is partially filled by a young, unvegetated
stratovolcano that rises about 1300 m above the caldera floor to a height
comparable to the caldera rim. It 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. The largest
historical eruption took place in 2002, producing a 17-km-high eruption
column, pyroclastic flows that traveled up to 8 km, and lava flows from
summit and flank vents.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNJRiCf2s$


Sangay  | Ecuador  | 2.005°S, 78.341°W  | Summit elev. 5286 m

IG reported a high level of activity at Sangay during 28 September-5
October. Weather clouds and rain sometimes prevented visual and webcam
observations of the volcano. Ash plumes were identified in satellite images
by the Washington VAAC or in webcam views during 30 September-1 October and
3 and 5 October; plumes rose 500-1,200 m above the volcano and drifted W
and SW. Thermal anomalies over the volcano were often visible in satellite
data. An active lava flow on the flanks was visible during a break in the
weather cloud cover the evening of 4 October.

Geologic Summary. The isolated Sangay volcano, located east of the Andean
crest, is the southernmost of Ecuador's volcanoes and its most active. The
steep-sided, glacier-covered, dominantly andesitic volcano grew within
horseshoe-shaped calderas of two previous edifices, which were destroyed by
collapse to the east, producing large debris avalanches that reached the
Amazonian lowlands. The modern edifice dates back to at least 14,000 years
ago. It towers above the tropical jungle on the east side; on the other
sides flat plains of ash have been sculpted by heavy rains into
steep-walled canyons up to 600 m deep. The earliest report of a historical
eruption was in 1628. More or less continuous eruptions were reported from
1728 until 1916, and again from 1934 to the present. The almost constant
activity has caused frequent changes to the morphology of the summit crater
complex.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
https://urldefense.com/v3/__http://www.igepn.edu.ec/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNJRiCf2s$


Semisopochnoi  | Aleutian Islands (USA)  | 51.93°N, 179.58°E  | Summit
elev. 1221 m

AVO reported that eruptive activity at Semisopochnoi's North Cerberus
crater continued during 29 September-5 October. Seismicity remained
elevated with intermittent explosion signals or bursts of activity likely
from explosions. A few explosions were also detected in regional infrasound
data during 2-5 October. Small ash clouds were observed almost daily in
either webcam or satellite images rising to altitudes below 3 km (10,000
ft) a.s.l.; plumes drifted ENE on 2 October, then N and NW on 3 October.
Sulfur dioxide plumes were possibly observed on a few days, though
definitely on 3 October. Webcams located 5-6 km from the active vent
recorded ashfall during 4-5 October. The Aviation Color Code remained at
Orange and the Volcano Alert Level remained at Watch.

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 Anvil Peak, a double-peaked
late-Pleistocene cone that forms much of the island's northern part. The
three-peaked Mount Cerberus was constructed within the caldera during the
Holocene. Each of the peaks contains a summit crater; lava flows on the N
flank of Cerberus appear younger than those on the south side. Other
post-caldera volcanoes include the symmetrical 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 eruptions have originated
from Cerberus, although Coats (1950) considered that both Sugarloaf and
Lakeshore Cone could have been recently active.

Source: US Geological Survey Alaska Volcano Observatory (AVO)
https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNR7b89pw$


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 24 September-1 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)
https://urldefense.com/v3/__http://www.kscnet.ru/ivs/kvert/index_eng.php__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNYuQRB_4$


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

JMA reported that 129 explosions at Suwanosejima's Ontake Crater produced
eruption plumes that rose as high as 3 km above the crater rim during 27
September-4 October. Large volcanic bombs were ejected as far as1 km from
the crater. Crater incandescence was visible nightly. The Alert Level
remained at 3 and the public was warned to stay 2 km away from the crater.

Geologic Summary. The 8-km-long, spindle-shaped island of Suwanosejima in
the northern Ryukyu Islands consists of an andesitic stratovolcano with two
historically active summit craters. The summit is truncated by a large
breached crater extending to the sea on the east flank that was formed by
edifice collapse. Suwanosejima, one of Japan's most frequently active
volcanoes, was in a state of intermittent strombolian activity from Otake,
the NE summit crater, that began in 1949 and lasted until 1996, after which
periods of inactivity lengthened. The largest historical eruption took
place in 1813-14, when thick scoria deposits blanketed residential areas,
and the SW crater produced two lava flows that reached the western coast.
At the end of the eruption the summit of Otake collapsed forming a large
debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which
extends to the eastern coast. The island remained uninhabited for about 70
years after the 1813-1814 eruption. Lava flows reached the eastern coast of
the island in 1884. Only about 50 people live on the island.

Source: Japan Meteorological Agency (JMA)
https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqN_NpHYWE$


Taal  | Luzon (Philippines)  | 14.002°N, 120.993°E  | Summit elev. 311 m

PHIVOLCS reported that sulfur dioxide emissions at Taal averaged 8,854
tonnes/day beginning on 27 September, and peaked on 5 October at 25,456
tonnes/day which was the highest ever sulfur dioxide gas flux recorded at
the volcano. On 27 September the number of daily volcanic earthquakes
significantly decreased. During 27 September-5 October upwelling of hot
volcanic fluids in the lake was visible and gas-and-steam plumes rose as
high as 3 km above the lake. The report noted that a sudden increase in
inflation below Taal Volcano Island was recorded in August. The Volcano
Alert Level remained at a 2 (on a scale of 0-5). PHIVOLCS reminded the
public that the entire Taal Volcano Island is a Permanent Danger Zone (PDZ)
and that boating on Taal Lake was prohibited.

Geologic Summary. Taal is one of the most active volcanoes in the
Philippines and has produced some of its most powerful historical
eruptions. Though not topographically prominent, its prehistorical
eruptions have greatly changed the landscape of SW Luzon. The 15 x 20 km
Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2
surface lies only 3 m above sea level. The maximum depth of the lake is 160
m, and several eruptive centers lie submerged beneath the lake. The
5-km-wide Volcano Island in north-central Lake Taal is the location of all
historical eruptions. The island is composed of coalescing small
stratovolcanoes, tuff rings, and scoria cones that have grown about 25% in
area during historical time. Powerful pyroclastic flows and surges from
historical eruptions have caused many fatalities.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
https://urldefense.com/v3/__http://www.phivolcs.dost.gov.ph/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNYyVaKKc$


Telica  | Nicaragua  | 12.606°N, 86.84°W  | Summit elev. 1036 m

INETER reported that on 4 September a diffuse ash plume from Telica rose
1.2 km (4,000 ft) a.s.l. and drifted less than 10 km WSW, based on
satellite images and model data.

Geologic Summary. Telica, one of Nicaragua's most active volcanoes, has
erupted frequently since the beginning of the Spanish era. This volcano
group consists of several interlocking cones and vents with a general NW
alignment. Sixteenth-century eruptions were reported at symmetrical Santa
Clara volcano at the SW end of the group. However, its eroded and breached
crater has been covered by forests throughout historical time, and these
eruptions may have originated from Telica, whose upper slopes in contrast
are unvegetated. The steep-sided cone of Telica is truncated by a
700-m-wide double crater; the southern crater, the source of recent
eruptions, is 120 m deep. El Liston, immediately E, has several nested
craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE
of Telica, form a prominent geothermal area frequented by tourists, and
geothermal exploration has occurred nearby.

Source: Instituto Nicaragüense de Estudios Territoriales (INETER)
https://urldefense.com/v3/__http://www.ineter.gob.ni/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNsRwYAe8$


Yasur  | Vanuatu  | 19.532°S, 169.447°E  | Summit elev. 361 m

On 30 September the Vanuatu Meteorology and Geo-Hazards Department (VMGD)
reported that seismic data and recent visual observations at Yasur
confirmed ongoing explosions and gas-and-ash emissions. A few earthquakes
were recorded on 28 September. The Alert Level remained at 2 (on a scale of
0-4). VMGD reminded residents and tourists that hazardous areas were near
and around the volcanic crater, within a 600-m-radius exclusion zone, and
that volcanic ash and gas could reach areas impacted by trade winds.

Geologic Summary. Yasur, the best-known and most frequently visited of the
Vanuatu volcanoes, has been in more-or-less continuous Strombolian and
Vulcanian activity since Captain Cook observed ash eruptions in 1774. This
style of activity may have continued for the past 800 years. Located at the
SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a
nearly circular, 400-m-wide summit crater. The active cone is largely
contained within the small Yenkahe caldera, and is the youngest of a group
of Holocene volcanic centers constructed over the down-dropped NE flank of
the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the
Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with
eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along
the Yenkahe horst accompanying eruptions has raised Port Resolution harbor
more than 20 m during the past century.

Source: Vanuatu Meteorology and Geo-Hazards Department (VMGD)
https://urldefense.com/v3/__http://www.geohazards.gov.vu/__;!!IKRxdwAv5BmarQ!IzLHJf7EFmKb3PGDBV9a4rM2sREcXXACaq6ai7DHne4YNKJBI9y1iLqNAy976cQ$



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==============================================================



Volcano Listserv is a collaborative venture among Arizona State University
(ASU), Portland State University (PSU), the Global Volcanism Program (GVP)
of the Smithsonian Institution's National Museum of Natural History, and
the International Association for Volcanology and Chemistry of the Earth's
Interior (IAVCEI).



ASU - http://www.asu.edu/

PSU - https://urldefense.com/v3/__http://pdx.edu/__;!!IKRxdwAv5BmarQ!Ip1SXjGKhVvuxlOe0uyQ27UHCifxBN0_aAhRDfy9yqFQmdST2ienONTg_OZzATU$ 

GVP - https://urldefense.com/v3/__http://www.volcano.si.edu/__;!!IKRxdwAv5BmarQ!Ip1SXjGKhVvuxlOe0uyQ27UHCifxBN0_aAhRDfy9yqFQmdST2ienONTgcahTt_c$ 

IAVCEI - https://urldefense.com/v3/__https://www.iavceivolcano.org/__;!!IKRxdwAv5BmarQ!Ip1SXjGKhVvuxlOe0uyQ27UHCifxBN0_aAhRDfy9yqFQmdST2ienONTg7aLiq4g$ 



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End of Volcano Digest - 4 Oct 2021 to 6 Oct 2021 (#2021-94)
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