4-4-4-4-4-4-4-4-4-4-4-4-4 From: "Kuhn, Sally" <KUHNS@xxxxxx> Smithsonian / USGS Weekly Volcanic Activity Report 13-19 August 2025 Sally Sennert - Weekly Report Editor (kuhns@xxxxxx) URL: https://volcano.si.edu/reports_weekly.cfm <https://urldefense.com/v3/__https://volcano.si.edu/reports_weekly.cfm__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15effe27VlA$> New Activity/Unrest: Dempo, Indonesia | Karymsky, Russia | Kirishimayama, Japan | Klyuchevskoy, Russia | Krasheninnikov, Russia | Lewotobi, Indonesia | Telica, Nicaragua Ongoing Activity: Aira, Japan | Dukono, Indonesia | Etna, Italy | Fuego, Guatemala | Great Sitkin, United States | Home Reef, Tonga | Ibu, Indonesia | Karangetang, Indonesia | Kilauea, United States | Lewotolok, Indonesia | Marapi, Indonesia | Merapi, Indonesia | Poas, Costa Rica | Popocatepetl, Mexico | Santa Maria, Guatemala | Semeru, Indonesia | Sheveluch, Russia | Spurr, United States | Stromboli, Italy | Suwanosejima, Japan 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 Dempo | Indonesia | 4.016°S, 103.121°E | Summit elev. 3142 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruptive event at Dempo was recorded at 0748 on 19 August and lasted nearly two minutes based on the seismic network. A dense white steam, gas, and ash plume rose 1.3 km above the summit and drifted S. The number of deep volcanic earthquakes had increased in early July, and deformation networks indicated inflation beneath the W flank, especially during the week prior to the eruption. According to news articles about 60 climbers were at or near the summit when the eruption occurred. The Alert Level remained at 2 (on a scale of 1-4), and the public were reminded to stay 1 km away from the crater and as far as 2 km on the N flank. Geologic Summary. Dempo is a stratovolcano that rises above the Pasumah Plain of SE Sumatra. The andesitic complex has two main peaks, Gunung Dempo and Gunung Marapi, constructed near the SE rim of a 3-km-wide amphitheater open to the north. The high point of the older Gunung Dempo crater rim is slightly lower, and lies at the SE end of the summit complex. The taller Marapi cone was constructed within the older crater. Remnants of seven craters are found at or near the summit, with volcanism migrating WNW over time. The active 750 x 1,100 m active crater cuts the NW side of the Marapi cone and contains a 400-m-wide lake at the far NW end. Eruptions recorded since 1817 have been small-to-moderate explosions that produced local ashfall. Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> ; Antara News https://www.antaranews.com/berita/5049025/badan-geologi-gunung-dempo-berubah-bentuk-lebih-tinggi-dalam-sepekan <https://urldefense.com/v3/__https://www.antaranews.com/berita/5049025/badan-geologi-gunung-dempo-berubah-bentuk-lebih-tinggi-dalam-sepekan__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ed6h2MEEw$> ; Kompas.com https://regional.kompas.com/read/2025/08/19/172107178/60-pendaki-terjebak-saat-gunung-dempo-erupsi-berikut-kondisi-terkini <https://urldefense.com/v3/__https://regional.kompas.com/read/2025/08/19/172107178/60-pendaki-terjebak-saat-gunung-dempo-erupsi-berikut-kondisi-terkini__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ecOKMyOvg$> Karymsky | Russia | 54.049°N, 159.443°E | Summit elev. 1513 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that moderate steam-and-gas activity continued at Karymsky during 7-14 August. A weak thermal anomaly over the volcano was observed in satellite images during 13-14 August; the volcano was quiet or obscured by clouds on the other days of the week. Explosions began at 2140 on 14 August producing an ash plume that rose 2 km (6,600 ft) a.s.l., or about 700 m above the summit. The ash plume was 12 x 12 km and had drifted about 26 km SE by 2140 based on satellite observations. The Aviation Color Code was raised to Orange (the third level on a four-color scale) at 2351. A daily thermal anomaly was identified in satellite images during 15-19 August. Dates and times are provided in Coordinated Universal Time (UTC); specific events are indicated in local time where specified. 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) http://kvert.febras.net/ <https://urldefense.com/v3/__http://kvert.febras.net/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeQHkBQ8g$> Kirishimayama | Japan | 31.934°N, 130.862°E | Summit elev. 1700 m The Japan Meteorological Agency (JMA) reported that eruptive activity continued at Shinmoedake (Shinmoe peak, a stratovolcano of the Kirishimayama volcano group) during 11-18 August. The number of volcanic earthquakes located beneath Shinmoedake, first detected in late October 2024, continued to be frequent; volcanic tremor was also occasionally detected, notably during eruptive events. Sulfur dioxide emissions on 12 August were characterized as high, averaging 1,000 tons per day. Ash plumes were continuously emitted during 0100-1650 on 13 August rising as high as 500 m above the crater rim and drifting N and NW. At 1050 and 1422 on 15 August ash plumes rose 300 m above the crater rim into weather clouds. The Alert Level remained at 3 (on a 5-level scale) and the public was warned to exercise caution within 3 km from Shinmoedake Crater. Geologic Summary. Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef916Oziw$> Klyuchevskoy | Russia | 56.056°N, 160.642°E | Summit elev. 4754 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that the eruption at Klyuchevskoyâ??s summit crater continued at variable levels during 13-15 August and then ended by 18 August. During 13-14 August lava advanced down the snowy W flank, causing phreatic explosions and lahars. Explosions at the summit produced ash plumes that rose as high as 6.5 km (21,300 ft) a.s.l., or about 1.8 km above the summit, and drifted as far as 300 km SW. Some ash plumes rose higher, 7.5 km (24,600 ft) a.s.l., as they drifted downwind. Taller ash plumes were visible in webcam images at 0432 on 14 August rising to 8.5 km (27,900 ft) a.s.l., or about 3.7 km above the summit, and drifting 95 km E. The Aviation Color Code (ACC) was raised to Red (the highest level on a four-color scale) at 0438. Within two hours, ash plume altitudes decreased to 6 km (19,700 ft) a.s.l., or about 1.2 km above the summit, and drifted 100 km E; at 0624 the ACC was lowered back to Orange. Explosions later that day generated ash plumes, that were visible in webcam images at 2150, rising 7-8 km (23,000-26,200 ft) a.s.l., or 2.2-3.2 km above the summit; plumes were visible in satellite data as far as 520 km E. Explosions the next day sent ash plumes to 9 km (29,500 ft) a.s.l., or about 4.2 km above the summit, that drifted 35 km NE based on webcam images at 0330 on 15 August. The ACC was raised to Red at 0406. Explosions continued to produce ash plumes over the next few hours, but to lower altitudes, rising 7-8 km a.s.l. and drifting 100 km NE. The ACC was lowered back to Orange at 0935. Ash plumes continued to be visible in both satellite and webcam images, at least through 2340 on 15 August, rising 6-6.5 km a.s.l. KVERT reported that the eruption had ended on 16 August with only fumarolic activity observed during 16-18 August. The ACC was lowered to Yellow at 2318 on 18 August. Dates and times are provided in Coordinated Universal Time (UTC); specific events are indicated in local time where specified. Geologic Summary. Klyuchevskoy is the highest and most active volcano on the Kamchatka Peninsula. Since its origin about 6,000 years ago, this symmetrical, basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during approximately the past 3,000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 and 3,600 m elevation. Eruptions recorded since the late 17th century have resulted in frequent changes to the morphology of the 700-m-wide summit crater. These eruptions over the past 400 years have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://kvert.febras.net/ <https://urldefense.com/v3/__http://kvert.febras.net/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeQHkBQ8g$> Krasheninnikov | Russia | 54.596°N, 160.27°E | Summit elev. 1816 m The Kamchatkan Volcanic Eruption Response Team (KVERT) and reported that the eruption at Krasheninnikov continued during 12-19 August. A large bright thermal anomaly over the volcano was identified in satellite images on most days; weather clouds obscured views on 17 August. Ash plumes from explosions at the northern cone drifted as far as 170 km E and SE on 13 August. Explosions on 14 August generated ash plumes that reached 2-3 km a.s.l. and drifted 170 km SE based on satellite data. Branching lava flows on the NW flank were active at least through 15 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates and times are provided in Coordinated Universal Time (UTC); specific events are indicated in local time where specified. Geologic Summary. The late-Pleistocene to Holocene Krasheninnikov volcano is comprised of two overlapping stratovolcanoes within a 9 x 10 km Pleistocene caldera. Young lava flows from summit and flank vents descend both into the caldera and down its outer flanks, and older flows that covered much of the SE caldera rim extended downslope at least 7 km. Tephra deposits from the caldera-forming eruption directly overlie a 39,000 years before present (BP) tephra thought to be associated with the formation of Uzon caldera (Florenskii, 1988). The intra-caldera stratovolcanoes are situated along a NE-SW-trending fissure that has also produced zones of Holocene cinder cones extending 15-20 km beyond the caldera. Construction of the southern edifice began about 11,000 years BP and lasted for about 4,500 years; it has a summit crater about 800-900 m wide. The northern edifice was constructed during a cycle of similar length that began about 6,500 years ago; it has a summit crater about 1.5 km wide, within which is low cone with an 800-m-wide crater containing another small cone. An eruptive cycle during about 600-400 years BP (1350-1550 CE) produced the Pauk lava cone in the crater of the northern cone and the Yuzhny lava flow on SW flank outside the caldera, followed by the Molodoy flow from the upper SW flank (Ponomareva, 1987; Ponomareva and Tsyurupa, 1985; Ponomareva and Braitseva, 1990). Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://kvert.febras.net/ <https://urldefense.com/v3/__http://kvert.febras.net/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeQHkBQ8g$> Lewotobi | Indonesia | 8.542°S, 122.775°E | Summit elev. 1703 m On 16 August the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increased activity at Lewotobi Laki-laki after the 9 August eruption. At 1405 and 1747 on 13 August a white, gray, and brown ash plume and a gray-to-brown ash plume, respectively, rose around 200 m above the summit and drifted W and SW. Seismic data during 10-16 August, specifically an increase in non-harmonic tremor signals, indicated increased activity at shallow depths. In addition, deformation data indicated inflation. At 0800 on 16 August the Alert Level was raised to 4 (on a scale of 1-4) and increased the exclusion zone to a radius of 6 km from the center of Laki-laki and 7 km in a semicircle clockwise from the SW to the NE. At 1830 on 17 August a dense gray ash plume rose 1 km above the summit and drifted SW. Activity escalated on 18 August with multiple ash plumes observed through the day. During 0038-0221 dense gray ash plumes rose at least 8 km above the summit and drifted W and NW. Webcam images from 0040 and 0222 showed incandescent material on the upper flanks and ash plumes rising from the summit and from areas along the down-flank margins of the ejected material. Ash plumes continued to be produced for almost another hour, though at 0723 the ash plumes were lower, rising 3.5 km above the summit and drifting W and NW. Dense gray ash plumes recorded at 0834, 0857, and 0911 rose 3.5-4 km above the summit and drifted W and NW. Dense gray ash plumes in the afternoon, at 1622 and 1651, rose 800 m above the summit and drifted S and SW. At 1721 a dense gray ash plume rose at least 6 km above the summit and drifted W and NW. A white-and-gray ash plume at 2008 rose 500 m above the summit and drifted N and NE; a webcam image a minute later showed minor crater incandescence. According to a news report a half a dozen flights in and out of Maumere (61 km W), Ende (125 km WSW), and Bajawa (200 km W) were canceled due to ash in the air. Geologic Summary. The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the "husband and wife"). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan. Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> ; Antara News https://www.antaranews.com/berita/5047233/enam-penerbangan-batal-dampak-erupsi-gunung-lewotobi <https://urldefense.com/v3/__https://www.antaranews.com/berita/5047233/enam-penerbangan-batal-dampak-erupsi-gunung-lewotobi__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ed03GGzQg$> Telica | Nicaragua | 12.606°N, 86.84°W | Summit elev. 1036 m The Washington Volcanic Ash Advisory Center (VAAC) reported that on 18 August a diffuse ash plume at Telica was visible in webcam images rising to 1.5 km (5,000 ft) a.s.l. and drifting SW. Weather clouds obscured satellite views. 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: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html <https://urldefense.com/v3/__http://www.ssd.noaa.gov/VAAC/messages.html__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef6H87PkQ$> Ongoing Activity Aira | Japan | 31.5772°N, 130.6589°E | Summit elev. 1117 m The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Calderaâ??s Sakurajima volcano) during 11-18 August. Nightly crater incandescence visible in webcam images and very small eruptive events occasionally occurred. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of both the Minimadake and Showa craters. Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef916Oziw$> Dukono | Indonesia | 1.6992°N, 127.8783°E | Summit elev. 1273 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 13-19 August. Daily white-and-gray gas-and-ash plumes rose as high as 700 m above the summit and drifted W, NW, E, and NE. The Alert Level remained at Level 2 (on a scale of 1-4) and the public was warned to stay 4 km away from the Malupang Warirang Crater. Geologic Summary. The Dukono complex in northern Halmahera is on an edifice with a broad, low profile containing multiple peaks and overlapping craters. Almost continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the Gunung Mamuya cone, 10 km NE. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also had reported eruptions. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Etna | Italy | 37.748°N, 14.999°E | Summit elev. 3357 m The Sezione di Catania - Osservatorio Etneo (INGV) reported that eruptive activity at Etnaâ??s summit craters during 11-17 August was characterized by lava effusion and periodic reddish ash emissions at Bocca Nuova Crater, Strombolian activity at SE Crater, and gas emissions at both NE Crater and Voragine. Lava effusion restarted at 1245 on 14 August along the N-S-trending fissure located between Bocca Nuova and SE Crater at a vent around 2,980 m elevation. Observatory staff on site noted that the fissure had propagated SW and that a new NE-SW-trending fracture field had developed in the area. The initial lava flow was 2-3 m wide and was followed by a more dominant flow that advanced SW. By 1000 on 15 August the lava flow was about 500 m long. During field inspections on 17 and 19 August staff observed ongoing effusion and that a tube had formed over the proximal part of the flow. They also observed several ephemeral vents. Satellite images and field surveys revealed that the distal part of the main flow branched and traveled SW. The most advanced end of the flow reached 2,270 m elevation. Geologic Summary. Mount Etna, towering above Catania on the island of Sicily, has one of the world's longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank. Source: Sezione di Catania - Osservatorio Etneo (INGV) http://www.ct.ingv.it/ <https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15edvtXaHng$> Fuego | Guatemala | 14.4748°N, 90.8806°W | Summit elev. 3799 m The Instituto Nacional de SismologÃa, Vulcanologia, Meteorologia e HidrologÃa (INSIVUMEH) reported that eruptive activity at Fuego continued during 12-19 August. Daily Strombolian explosions were recorded by the seismic network at rates of 2-9 per hour when reported. The explosions generated daily gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted 10-30 km NW, W, and SW. Rumbling sounds, shock waves, and sound associated with gas emissions were occasionally reported. Incandescence at the summit was visible during dark hours from 13 August to 16 August. Ashfall was reported on most days in areas downwind including Panimache I and II (8 km SW), Morelia (10 km SW), Santa Sofia (12 km SW), and El Porvenir (11 km SW). During the early afternoon on 12 August and around noon on 16 August lahars descended the Ceniza, Zarco, Mazate, El Jute, and Las Lajas drainages, carrying tree branches, trunks, volcanic material, and blocks as large as 3 m in diameter. Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. 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 the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous 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. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ <https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15efTY565Sw$> Great Sitkin | United States | 52.076°N, 176.13°W | Summit elev. 1740 m The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkinâ??s summit crater during 12-19 August. Satellite data indicated that the flow was advancing S, with some rockfalls occurring along the S and E margins. Small daily earthquakes were detected by the seismic network, including signals probably caused by the small rockfalls. Weather clouds mostly obscured satellite and webcam views; clear conditions during 13-14 August showed elected surface temperatures in satellite data and during 14-15 August a steam plume was visible in webcam images. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale). Geologic Summary. The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger 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 older edifice and produced a submarine debris avalanche. Deposits from this and an even 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. Eruptions have been recorded since the late-19th century. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ <https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15efx_q4rcA$> Home Reef | Tonga | 18.992°S, 174.775°W | Summit elev. -10 m The Tonga Geological Services reported no indications of activity at Home Reef during 2-16 August. A comparison of satellite images from 15 July and 11 August showed new deposits of eroded material at the NW coastline and sharp edges along the SE coastline from wind and wave action. Yellow sulfur deposits in and around the main crater were more prominent in the 11 August image, suggesting that emissions of steam and sulfur dioxide gas were continuing; a diffuse plume was visible in both images. Discolored water around the island was visible in both images. The Aviation Color Code remained at Yellow (the second lowest level on a four-level scale, the Maritime Alert Level remained at Orange (the third level on a four-level scale) with advice to stay at least 2 nautical miles (3.7 km) from the island, and the Alert Level for residents of Vavaâ??u and Haâ??apai remained at Green (the first level on a four-level scale). Geologic Summary. Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, large amounts of floating pumice, and an ephemeral 500 x 1,500 m island, with cliffs 30-50 m high that enclosed a water-filled crater. In 2006 an island-forming eruption produced widespread dacitic pumice rafts that drifted as far as Australia. Another island was built during a September-October 2022 eruption. Source: Tonga Geological Services, Government of Tonga https://www.facebook.com/tongageologicalservice <https://urldefense.com/v3/__https://www.facebook.com/tongageologicalservice__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef0sK5QxQ$> Ibu | Indonesia | 1.488°N, 127.63°E | Summit elev. 1325 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 13-19 August. Daily dense gray ash plumes rose 400-700 m above the summit and drifted in multiple directions. The Alert Level remained at 3 (the second highest level on a four-level scale) and the public was advised to stay 4 km away from the active crater and 5 km away from the N crater wall opening. Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Karangetang | Indonesia | 2.781°N, 125.407°E | Summit elev. 1797 m In a special statement the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increased seismic activity at Karangetang. An increase in earthquake signals indicating gas emissions was recorded on 5 August with 40 events. Seismicity again increased; on 17 August the seismic network recorded 96 events indicating gas emissions along with 13 episodes of harmonic tremor. The Alert Level remained at 2 (on a scale of 1-4) and the public was advised to stay 1.5 km away from both the Kawah Dua (North Crater) and the Main Crater (South Crater) and 2.5 km away from the SW and S flanks of Main Crater. Geologic Summary. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented (Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Kilauea | United States | 19.421°N, 155.287°W | Summit elev. 1222 m The Hawaiian Volcano Observatory (HVO) reported that the eruption within Kilaueaâ??s Kaluapele summit caldera, characterized by episodic fountaining, incandescence, and intermittent spatter at vents along the SW margin of Halemaâ??umaâ??u Crater, continued at variable levels during 12-19 August. Low-frequency tremor bursts characteristic of gas pistoning persisted during most of the week. Incandescence at the S vent was visible during the first half of the week and then diminished. Incandescence that had reappeared at the N vent and cracks above it intensified overnight during 15-16 August. Strong incandescence and spattering at the N vent were visible during 17-18 August, along with overnight incandescence at the cracks above the N vent. Gas pistoning stopped around 0000 on 19 August at the same time that tremor became more continuous and was punctuated by bursts. Incandescence at the N vent decreased. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale). Geologic Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) https://volcanoes.usgs.gov/observatories/hvo/ <https://urldefense.com/v3/__https://volcanoes.usgs.gov/observatories/hvo/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ee3_4PX2Q$> Lewotolok | Indonesia | 8.274°S, 123.508°E | Summit elev. 1431 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruption at Lewotolok was ongoing during 13-19 August. Daily white-to-gray, gray, or gray-to-black ash plumes rose 300-800 m above the summit of the cone and drifted 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. 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) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Marapi | Indonesia | 0.38°S, 100.474°E | Summit elev. 2885 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Marapi (on Sumatra) continued during 13-19 August. At 1202 on 13 August an eruptive event generated a white-and-gray ash plume that rose 500 m above the summit and drifted NE. An eruptive event was recorded at 0119 on 16 August but not visually observed. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the active crater. Geologic Summary. Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra's most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Merapi | Indonesia | 7.54°S, 110.446°E | Summit elev. 2910 m The Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG) reported that the eruption at Merapi (on Java) continued during 8-14 August. Earthquakes were about the same intensity compared to the previous week. The SW lava dome produced 15 lava avalanches that traveled as far as 2 km SW down the Bebeng drainage, 13 that traveled as far as 2 km SW down the Krasak drainage, and 58 that traveled as far as 2 km W down the Sat/Putih drainage. Small morphological changes to the SW lava dome resulted from lava effusion and minor collapses. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 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) http://www.merapi.bgl.esdm.go.id/ <https://urldefense.com/v3/__http://www.merapi.bgl.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ecmn6v81Q$> Poas | Costa Rica | 10.2°N, 84.233°W | Summit elev. 2697 m The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported continuing gas-and-steam emissions with occasional minor amounts of ash at Poás during 12-19 August. Variable incandescence at Boca A vent continued to be visible at night. An ash emission lasting about 12 minutes began at 1710 on 15 August, rose 200 m above the crater rim, and drifted W. The volcanic Alert Level remained at 2 (the second lowest level on a four-level scale) and the Aviation Color Code remained at Yellow (the second lowest color on a four-color scale). Geologic Summary. The broad vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the complex stratovolcano extends to the lower N flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, last erupted about 7,500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since an eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water. Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/ <https://urldefense.com/v3/__http://www.ovsicori.una.ac.cr/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ed8TJrDlg$> Popocatepetl | Mexico | 19.023°N, 98.622°W | Summit elev. 5393 m The Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 12-19 August. The seismic network recorded 22-60 long-period events per day, accompanied by steam-and-gas emissions with occasional ash content. In addition, the seismic network recorded daily periods of low-amplitude tremor, sometimes characterized by harmonic and high-frequency signals, lasting from three hours and 44 minutes to just over 14 hours. According to the Washington VAAC ash plumes visible in webcam and/or satellite images during 12, 14, and 16-19 August rose 5.8-6.7 km (19,000-22,000 ft) a.s.l., or as high as 1.3 km above the summit, and drifted NW, W, and SW. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater. Geologic Summary. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time. Sources: Centro Nacional de Prevencion de Desastres (CENAPRED) https://www.gob.mx/cenapred <https://urldefense.com/v3/__https://www.gob.mx/cenapred__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15edybTtk6g$> ; Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html <https://urldefense.com/v3/__http://www.ssd.noaa.gov/VAAC/messages.html__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef6H87PkQ$> Santa Maria | Guatemala | 14.757°N, 91.552°W | Summit elev. 3745 m The Instituto Nacional de SismologÃa, VulcanologÃa, MeteorologÃa e HidrologÃa (INSIVUMEH) reported high levels of ongoing eruptive activity at Santa Mariaâ??s Santiaguito dome complex during 12-19 August, with continuing lava extrusion at Caliente dome. Daily explosions, 1-2 per hour when reported, generated gas-and-ash plumes that rose 800-900 m above the dome and drifted W and SW. Effusion of blocky lava and collapses of previous deposits produced block avalanches that descended mainly the W and SW flanks; the collapsed material produced short pyroclastic flows that descended the SW and S flanks during 12-13 August. Incandescence during dark hours was visible from Caliente dome and block avalanches. During the early afternoon of 12 August heavy rainfall generated lahars in the Tambor drainage (SSW) that carried blocks up to 1 m in diameter mixed with fine sediment, tree trunks, and branches. The lahars were hot and had a sulfur odor. Material accumulated at the W crater rim began collapsing at 1630 on 16 August, generating pyroclastic flows that descended the San Isidro drainage as far as 4 km. Associated gas-and-ash plumes rose 1 km and drifted 30-60 km W and SW, causing abundant ashfall in San Marcos Palajunoj (8 km SW), Loma Linda (7 km W), San MartÃn Sacatepéquez (11 km NW), and Colomba (18 km WSW) and minor ashfall in more distance areas including La Reforma (28 km WNW), El Quetzal (26 km WNW), Coatepeque (31 km W), and Pajapita (50 km W). In the early evening of 16 August minor lahars descended the Zanjón Seco (SW) and Tambor River channels. Geologic Summary. Symmetrical, forest-covered Santa MarÃa volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic andesite stratovolcano. The massive 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 vents, with activity progressing E towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ <https://urldefense.com/v3/__http://www.insivumeh.gob.gt/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15efTY565Sw$> Semeru | Indonesia | 8.108°S, 112.922°E | Summit elev. 3657 m The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru during 6-12 August, often with multiple daily eruptive events recorded by the seismic network. Daily white-and-gray ash plumes rose 500-1,000 m above the summit and drifted in multiple directions. Minor incandescence at the summit was visible in a webcam image at 2229 on 17 August. The Alert Level remained at 2 (the second lowest level on a scale of 1-4). The public was warned to stay at least 3 km away from the summit in all directions, 8 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 13 km from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards. Geologic Summary. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ <https://urldefense.com/v3/__http://vsi.esdm.go.id/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeU-ZzVPg$> Sheveluch | Russia | 56.653°N, 161.36°E | Summit elev. 3283 m The Kamchatkan Volcanic Eruption Response Team (KVERT) reported continuing eruptive activity at Sheveluchâ??s â??300 years of RASâ?? dome on the SW flank of Old Sheveluch and at the Young Sheveluch dome during 8-14 August. Thermal anomalies over the domes were identified in satellite images during 13-14 August; weather clouds obscured views on the other days. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC; specific events are in local time where noted. Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. 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 occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. 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://kvert.febras.net/ <https://urldefense.com/v3/__http://kvert.febras.net/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15eeQHkBQ8g$> Spurr | United States | 61.299°N, 152.251°W | Summit elev. 3374 m The Alaska Volcano Observatory (AVO) reported that over the past several months Spurr had exhibited decreasing signs of volcanic unrest, including small earthquakes, gas emissions, melting ice, and surface changes. Ground deformation had not been detected since March 2025. The data suggested that movement of magma toward the surface, which began in early 2024, had stopped. At 1007 on 20 August the Volcano Alert Level was lowered to Normal (the lowest level on a four-level scale) and the Aviation Color Code was lowered to Green (the lowest level on a four-color scale). Geologic Summary. Mount Spurr is the closest volcano to Anchorage, Alaska (130 km W) and just NE of Chakachamna Lake. The summit is a large lava dome at the center of a roughly 5-km-wide amphitheater open to the south formed by a late-Pleistocene or early Holocene debris avalanche and associated pyroclastic flows that destroyed an older edifice. The debris avalanche traveled more than 25 km SE, and the resulting deposit contains blocks as large as 100 m in diameter. Several ice-carved post-collapse cones or lava domes are present. The youngest vent, Crater Peak, formed at the southern end of the amphitheater and has been the source of about 40 identified Holocene tephra layers. Eruptions from Crater Peak in 1953 and 1992 deposited ash in Anchorage. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ <https://urldefense.com/v3/__https://avo.alaska.edu/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15efx_q4rcA$> Stromboli | Italy | 38.789°N, 15.213°E | Summit elev. 924 m The Sezione di Catania - Osservatorio Etneo (INGV) reported that eruptive activity continued at Stromboli during 11-17 August. Webcam images showed Strombolian activity at four vents in Area N within the upper part of the Sciara del Fuoco, and from at least two vents in Area C-S (South-Central Crater) on the crater terrace. The vents in Area N continued to produce low- to medium-intensity explosions at a rate of 10-14 events per hour, ejecting lapilli and bombs less than 150 m above the vents. Weak spattering at N2 was visible on 17 August. Low- to medium-intensity explosions ejected ash from the vents in Area C-S at a rate of 1-4 times per hour. The Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile. Geologic Summary. Spectacular incandescent nighttime explosions at Stromboli have long attracted visitors to the "Lighthouse of the Mediterranean" in the NE Aeolian Islands. This volcano has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent scarp that formed about 5,000 years ago due to a series of slope failures which extends to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium. Sources: Sezione di Catania - Osservatorio Etneo (INGV) http://www.ct.ingv.it/ <https://urldefense.com/v3/__http://www.ct.ingv.it/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15edvtXaHng$> ; Dipartimento della Protezione Civile https://www.protezionecivile.gov.it/it/ <https://urldefense.com/v3/__https://www.protezionecivile.gov.it/it/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef1UkkJuQ$> Suwanosejima | Japan | 29.638°N, 129.714°E | Summit elev. 796 m The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 11-18 August. Incandescence was observed nightly in webcam images. Volcanic earthquakes below the W flank had been at low levels but became more frequent on 14 August. Explosions at 2130 on 13 August, at 2046 on 14 August, at 0023 and 0049 on 15 August, at 2102 on 15 August, and at 0237 on 16 August produced ash plumes that rose as high as 1.4 km above the crater rim and drifted SW and W; plumes from the first and last explosions were not characterized. Large blocks were ejected 700 m above the crater rim. Eruptive events during 14-16 and 18 August produced ash plumes that rose as high as 1.4 km above the crater rim and drifted SW, W, and NW. The Alert Level remained at 2 (the second level on a five-level scale) and the public was warned to be cautious within 1.5 km of the crater. Geologic Summary. The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan's most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered 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 an open collapse scarp extending 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) http://www.jma.go.jp/jma/ <https://urldefense.com/v3/__http://www.jma.go.jp/jma/__;!!IKRxdwAv5BmarQ!Y_rrbnxo9waMFqGPcxARx5PSEsWt2saa_MsiZQAA3wGS5CszCdUU0iAmSUWno0oS9qnqWBM1XqYlGmF15ef916Oziw$> 4-4-4-4-4-4-4-4-4-4-4-4-4 ============================================================== 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). 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