The Weekly Volcanic Activity Report: June 30 - July 6, 2021

The Weekly Volcanic Activity Report: June 30 - July 6, 2021

New activity/unrest was reported for 6 volcanoes from June 30 to July 6, 2021. During the same period, ongoing activity was reported for 15 volcanoes.

New activity/unrest: Copahue, Central Chile-Argentina border | Krakatau, Indonesia | Rincon de la Vieja, Costa Rica | Sarychev Peak, Matua Island (Russia) | Suwanosejima, Ryukyu Islands (Japan) | Taal, Luzon (Philippines).

Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Etna, Sicily (Italy) | Kadovar, Papua New Guinea | Karymsky, Eastern Kamchatka (Russia) | Krysuvik-Trolladyngja, Iceland | Kuchinoerabujima, Ryukyu Islands (Japan) | Lewotolok, Lembata Island (Indonesia) | Merapi, Central Java (Indonesia) | Reventador, Ecuador | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Stromboli, Aeolian Islands (Italy) | Telica, Nicaragua.

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 23:00 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.

New activity/unrest

Copahue, Central Chile-Argentina border

37.856°S, 71.183°W, Summit elev. 2953 m

SERNAGEOMIN and SEGEMAR reported increased activity at Copahue, beginning with minor, sporadic increases in tremor first detected at the end of May. During 30 June-2 July tremor was elevated and volume of water in the crater lake decreased significantly. Coincidently crater incandescence was visible in nighttime webcam views and gas emissions increased. Residents reported volcanic gas odors. Increased gas-and-steam emissions during 1100-1400 on 2 July contained minor amounts of ash that left visible deposits on the SE and ENE flanks. The Alert Level remained at Green (the lowest level on a four-color scale).

Geological summary: Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

Krakatau, Indonesia

6.102°S, 105.423°E, Summit elev. 155 m

The Darwin VAAC reported that on 2 July ash plumes from Anak Krakatau rose to 1.5 km (5,000 ft) a.s.l. and drifted SW.

Geological summary: The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927.

Rincon de la Vieja, Costa Rica

10.83°N, 85.324°W, Summit elev. 1916 m

OVSICORI-UNA reported that an eruption at Rincón de la Vieja was recorded at 0838 on 1 July, though weather conditions prevented visual conformation of emissions. Small emissions were visible at 0937, 0940, and 1006 on 3 July. Small steam plumes were seen on 4 July, but too small to be recorded by the seismic network.

Geological summary: Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A Plinian eruption producing the 0.25 km3 Río Blanca tephra about 3,500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.

Sarychev Peak, Matua Island (Russia)

48.092°N, 153.2°E, Summit elev. 1496 m

The Tokyo VAAC and SVERT reported that during 30 June-1 July ash plumes from Sarychev Peak rose to 3-5.5 km (10,000-18,000 ft) a.s.l. and drifted W, SE, and E based on satellite images. Plumes drifted as far as 25 km E on 1 July. The Alert Level remained at Yellow (the second lowest level on a four-color scale).

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

Suwanosejima, Ryukyu Islands (Japan)

29.638°N, 129.714°E, Summit elev. 796 m

JMA reported that 35 explosions at Suwanosejima's Ontake Crater produced eruption plumes that rose as high as 2 km above the crater rim during 28 June-5 July. Large volcanic bombs were ejected 400 m from the crater and crater incandescence was visible nightly. Eruption sounds were heard in Toshima village (4 km SSW). The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Geological 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.

Taal, Luzon (Philippines)

14.002°N, 120.993°E, Summit elev. 311 m

PHIVOLCS reported that anomalously high sulfur dioxide emissions were recorded at Taal, averaging 14,241 and 13,287 tonnes/day on 28 June and 1 July, respectively. Upwelling of hot volcanic fluids in the crater lake produced steam-and-gas plumes that rose as high as 3 km. Vog in the vicinity of the volcano persisted.

At 1516 on 1 July a phreatomagmatic eruption generated a dark, 5-minute-long, Surtseyan plume that rose 1 km above the lake. The Alert Level was raised to 3 (on a scale of 0-5) at 1537. According to news articles and the Philippine Coast Guard, authorities began evacuating residents in Banyaga, Bilibinwang, Gulod, Boso-boso, and Lakeshore Bugaan East around 1700. Four additional short eruptions (less than two minutes) were recorded at 1826, 1921, 1941, and 2020, each ejecting material as high as 200 m. PHIVOLCS noted that TVI is a Permanent Danger Zone (PDZ), and entry into the island as well as high-risk barangays of Agoncillo and Laurel is prohibited.

More phreatomagmatic eruptions on 2 July, at 1025, 1047, and 1101, jetted material 100 m above the lake. Sulfur dioxide emissions averaged 10,254 tonnes/day. Vigorous upwelling in the lake was visible in the afternoon, and steam-and-gas plumes that rose as high as 3 km drifted SW and NW. On 3 July steam-and-gas plumes rose 2.5-3 km and drifted SW and NW. Sulfur dioxide emissions averaged 14,699 tonnes/day, the highest ever measured from Taal. The high emissions and weather conditions again created vog in the area. A news article noted that about 10 children showed signs of illness from the vog.

On 4 July PHIVOLCS issued a special advisory noting, again, a new record-breaking high of sulfur dioxide emissions at 22,628 tonnes/day. A total of 26 strong and very shallow low-frequency volcanic earthquakes below the E part of TVI had been recorded since the beginning of the day. Some of the earthquakes were accompanied by rumbling and weakly felt by fish cage caretakers off the NE shore. Lake upwelling persisted during 5-6 July with steam-and-gas plumes rising 2.5-3 km. Sulfur dioxide emissions averaged 5,299 tonnes/day on 5 July. The DROMIC report stated that 3,027 people were in 20 evacuation centers, and 2,759 people were in private residences by 6 July.

Geological 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.

Ongoing activity

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported nightly incandescence during 28 June-5 July from Minamidake Crater (at Aira Caldera’s Sakurajima volcano). An eruptive event on 29 June produced an ash plume that rose 1 km before entering weather clouds. The sulfur dioxide emission rate was low at 600 tons per day on 30 June. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Geological 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.

Dukono, Halmahera (Indonesia)

1.693°N, 127.894°E, Summit elev. 1229 m

Based on satellite and wind model data, the Darwin VAAC reported that during 29 June-3 July ash plumes from Dukono rose to 2.1 km (7,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Geological summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

Ebeko, Paramushir Island (Russia)

50.686°N, 156.014°E, Summit elev. 1103 m

According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 27-28 June and 1 July produced ash plumes that rose as high as 2 km (6,600 ft) a.s.l. and drifted in multiple directions. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Etna, Sicily (Italy)

37.748°N, 14.999°E, Summit elev. 3320 m

INGV reported three episodes of lava fountaining at Etna’s Southeast Crater (SEC) during 28 June-4 July, producing ash plumes that rose 5-10 km (16,400-32,800 ft) a.s.l. Occasional ash-and-gas emissions rose from Bocca Nuova Crater and Northeast Crater. The first episode at SEC began with Strombolian activity at 0040 on 2 July. Ash plumes drifted ESE and within an hour lava fountains were visible that sent flows SW; fountaining ceased at 0250. The second episode began at 1656 on 4 July, produced fountains at 1725, and ended at 1900. Lava flows traveled SW and ENE, and ash plumes drifted ESE. The last episode began at 2330 on 6 July and produced ash plumes that drifted SE. Explosive activity intensified at 0000 on 7 July; lava fountaining began 30 minutes later, rose as high as 1 km, and ended within two hours. Lapilli was reported in the S part of Tremestieri and ash fell in Nicolosi, as well as in many other areas downwind. According to news articles the Catania airport was closed during the night due to ashfall.

Geological summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical 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 horseshoe-shaped 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.

Kadovar, Papua New Guinea

3.608°S, 144.588°E, Summit elev. 365 m

Based on satellite and wind model data, the Darwin VAAC reported that on 4 July an ash plume from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted W.

Geological summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. It is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. Prior to an eruption that began in 2018, a lava dome formed the high point of the andesitic volcano, filling an arcuate landslide scarp open to the south; submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. A period of heightened thermal phenomena took place in 1976. An eruption began in January 2018 that included lava effusion from vents at the summit and at the E coast.

Karymsky, Eastern Kamchatka (Russia)

54.049°N, 159.443°E, Summit elev. 1513 m

KVERT reported that a thermal anomaly over Karymsky was visible in satellite images on 25 and 30 June and 1 July; the volcano was quiet or obscured by weather clouds on the other days during 26 June-2 July. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological 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.

Krysuvik-Trolladyngja, Iceland

63.917°N, 22.067°W, Summit elev. 360 m

The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, periodically continued during 30 June-6 July. Lava fountaining and overflows from the fifth vent were occasionally visible, and lava from the crater flowed in tubes as well as on the surface. Occasional rim collapses generated minor ash plumes on 2 July based on footage captured by a visitor. A longest pause in the eruption so far, also reflected in seismic data, began near midnight on 5 July and ended early on 7 July according to a news source. 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 warned of increased gas emissions hazards.

Geological 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.

Kuchinoerabujima, Ryukyu Islands (Japan)

30.443°N, 130.217°E, Summit elev. 657 m

JMA reported that deformation data at Kuchinoerabujima had shown a deflationary trend since February and the number of volcanic earthquakes had been decreasing since May. The Alert Level was lowered to 2 (on a scale of 1-5) on 5 July, and JMA reminded the public to stay 1 km away from Shindake Crater in general and 2 km away from the W flank.

Geological summary: A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Lewotolok, Lembata Island (Indonesia)

8.274°S, 123.508°E, Summit elev. 1431 m

PVMBG reported that daily white-and-gray plumes from Lewotolok rose as high as 1 km and drifted in multiple directions during 29 June-6 July. Incandescent material was ejected from the summit vent in various directions during 2-5 July; on 3 July material landed as far as 1 km SW and started vegetation fires. On 5 July an ash plume rose 1 km and drifted SE. 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.

Geological 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.

Merapi, Central Java (Indonesia)

7.54°S, 110.446°E, Summit elev. 2910 m

BPPTKG reported that the lava dome just below Merapi’s SW rim and the lava dome in the summit crater both remained active during 25 June-1 July. The SW rim lava-dome volume was an estimated 1.68 million cubic meters by 1 July, with a growth rate of 11,800 cubic meters per day, and continued to shed material down the flank. The summit lava dome was 0.5 m shorter than the previous week, corresponding to the increasing numbers of incandescent avalanches and pyroclastic flows as more material was shed to the SE. A total of 10 pyroclastic flows traveled a maximum of 2 km down the SW flank and 29 traveled as far as 3 km SE. As many as 100 incandescent avalanches traveled a maximum of 2 km down the SW flank and 26 traveled as far as 1.2 km down the SE flank. Ashfall was reported in several areas to the SE on 25 June. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the summit.

Geological 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.

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 June-6 July; adverse weather conditions sometimes prevented visual confirmation. Seismicity was characterized by daily explosions, harmonic tremor events, long-period earthquakes, and signals indicating emissions. Gas, steam, and ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose as high as 1.6 km above the summit crater and drifted mainly W, NW, and NE. Crater incandescence and incandescent blocks rolling down the S flank were often observed at night.

Geological 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.

Semeru, Eastern Java (Indonesia)

8.108°S, 112.922°E, Summit elev. 3657 m

Semeru continued to erupt during 29 June-6 July. Inclement weather often prevented visual observations, though PVMBG and the Darwin VAAC reported that gray-and-white plumes rose 500 m above the summit and drifted in multiple directions on 30 June and 1 and 3 July. The Alert Level remained at 2 (on a scale of 1-4), with a general exclusion zone of 1 km and extensions to 5 km in the SSE sector.

Geological 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.

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 25 June-2 July. An ash plume drifted 18 km SW on 30 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological 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.

Stromboli, Aeolian Islands (Italy)

38.789°N, 15.213°E, Summit elev. 924 m

INGV reported that during 28 June-4 July activity at Stromboli was characterized by ongoing explosive activity from three vents in Area N (North Crater area) and four vents in Area C-S (South-Central Crater area). Explosions from the N1 vent (Area N) ejected lapilli and bombs 150 m high, and produced minor ash emissions. Explosions at N2 vents (Area N) averaged 4-10 events per hour and ejected material 80 m high; spattering was intense on 28 June. Explosions from the S2 vents in Area C-S occurred at a rate of 5-8 events per hour and ejected coarse material more than 150 m high.

Geological summary: Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, 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 horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend 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.

Telica, Nicaragua

12.606°N, 86.84°W, Summit elev. 1036 m

INETER reported that at 0500 on 29 June ash-and-gas emissions from Telica rose 200 m above the crater rim and drifted SW. The Washington VAAC noted that ash was emitted during 2-3 July. A few discrete emissions and ash near the crater were visible in webcam images on 2 July, and possible diffuse ash just W of the crater was seen in satellite images. Plumes likely rose to 1.2-1.5 km (4,000-5,000 ft) a.s.l. Another steam-and-ash plume drifted SW and then turned N. On 3 July possible ash plumes rose to 1.5 km (5,000 ft) a.s.l. and drifted WSW.

Geological 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: GVP


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