The Weekly Volcanic Activity Report: January 3 - 9, 2018

The Weekly Volcanic Activity Report: January 3 - 9, 2018

New activity/unrest was reported for 2 volcanoes between January 3 and 9, 2018. During the same period, ongoing activity was reported for 11 volcanoes.

New activity/unrest: Agung, Bali (Indonesia) | Kadovar, Papua New Guinea.

Ongoing activity: Aira, Kyushu (Japan) | Aoba, Vanuatu | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Pacaya, Guatemala, Popocatepetl, Mexico | Rincon de la Vieja, Costa Rica | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Turrialba, Costa Rica.

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, notices of volcanic activity posted 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. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New activity/unrest

Agung, Bali (Indonesia)

8.343°S, 115.508°E, Summit elev. 2997 m

BNPB reported that activity at Agung continued to fluctuate at a high level. Visual observations as well as seismic, deformation, and geochemistry data indicated that the eruption was continuing, though deformation data in recent days showed a stagnant trend. As of the morning of 4 January BNPB noted that there were 70,610 evacuees spread out in 240 shelters. The exclusion zone was adjusted to 6 km in all directions that same day, allowing thousands of displaced people the option to return to their homes. An estimated 17,115 people in seven villages have residences within the 6-km-radius exclusion zone.

PVMBG reported that during 3-9 January gray-and-white plumes rose as high as 2 km above the crater rim and drifted in multiple directions. The Alert Level remained at 4 (on a scale of 1-4).

Geological summary: Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.

Kadovar, Papua New Guinea

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

The first confirmed historical eruption at Kadovar began around mid-day local time on 5 January, according to witnesses. The island is approximately 1.4 km in diameter with very steep slopes, located about 25 km NNE from the mouth of the Sepik River on the New Guinea mainland. The Rabaul Volcanological Observatory (RVO) warned of potential explosive activity, landslides, and resulting possible tsunamis.

Aerial photos and observations from Samaritan Air flights showed dark gray ash and steam plumes rising from a crater on the SE side of the summit. It was estimated that up to 60% of the island was covered in volcanic products, which primarily appeared to be ash along with some pyroclastic flows. Ashfall was reported on Kairiru and Mushu islands (115 km WNW), Mt. Uru in Yangoru (130 km W), and Woginara (140 km W), along with locations along the W coast of the Wewak District.

The NOAA/CIMSS Volcanic Cloud Monitoring system generated an alert for the ash cloud moving WNW, as imaged by S-NPP VIIRS at 0330 UTC on 5 January; Himawari-8 imagery subsequently showed that the eruption began around 0220 UTC. The Darwin VAAC issued a sequence of ash advisories starting on 5 January that noted ash moving W at an altitude of about 2.1 km (7,000 ft) a.s.l., and set the Aviation Color Code to Orange. Both discrete eruptions and continuous ongoing activity was seen in satellite imagery through 9 January, with the plume visible at distances of over 200 km W and WNW.

Although initial news reports regarding the population and evacuation status were unclear, the East Sepik Governor, Allan Bird, told media on 8 January that 591 residents of Kadovar had been evacuated to Blup Blup island (about 10 km N) due to the organizational efforts of village councilors on the two islands.

RVO stated that during 7-8 January ash continued to be emitted, and blown tens of kilometers WNW.

Geological summary: The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. Kadovar is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. The village of Gewai is perched on the crater rim. A 365-m-high lava dome forming the high point of the andesitic volcano fills an arcuate landslide scarp that is open to the south, and submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. No certain historical eruptions are known; the latest activity was a period of heightened thermal phenomena in 1976.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that very small events occurred at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 28 December 2017-4 January 2018. An event at 1744 on 6 January ejected material from Minamidake Crater as far as 900 m from the crater. An event at Showa Crater on 8 January at 0359 ejected material as far as 800 m. The Alert Level remained at 3 (on a 5-level scale).

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.

Aoba, Vanuatu

15.4°S, 167.83°E, Summit elev. 1496 m

Based on information from VGO, the Wellington VAAC reported that on 8 January ash from Aoba fell on the N and NE parts of the island; weather clouds prevented webcam and satellite observations. The next day a local observer saw an ash plume rising to an altitude of 2.1 km (7,000 ft) a.s.l. and drifting NW.

Geological summary: Aoba, also known as Ambae, is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Fuego, Guatemala

14.473°N, 90.88°W, Summit elev. 3763 m

INSIVUMEH reported that during 4-9 January explosions at Fuego generated ash plumes that rose as high as 1.1 km above the crater and drifted mainly 10-15 km S, SW, and W, with an occasional plume moving E or NE. Some of the explosions generated shock waves. Incandescent material was ejected 100-300 m above the crater rim, causing avalanches of material that traveled within the crater and sometimes down the Ceniza (SSW), Taniluyá (SW), and Seca (W), and Las Lajas (SE) drainages. Minor ashfall was noted in local areas including Panimaché I (8 km SW), Santa Sofía (12 km SW), Morelia (9 km SW), El Porvenir, La Rochela, and Ceylon.

Geological summary: Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Kilauea, Hawaiian Islands (USA)

19.421°N, 155.287°W, Summit elev. 1222 m

During 3-9 January HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Webcams recorded incandescence from long-active sources within Pu'u 'O'o Crater and from a small lava pond in a pit on the W side of the crater. Surface lava flows were active above and on the pali, and on the coastal plain.

Geological summary: Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Summit elev. 4754 m

Based on satellite observations KVERT reported that gas-and-steam plumes from Klyuchevskoy contained some ash and drifted about 150 km in multiple directions during 1 and 3-4 January. A weak thermal anomaly was visible on 3 January. The Aviation Color Code remained at Orange.

Geological summary: Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Pacaya, Guatemala

14.382°N, 90.601°W, Summit elev. 2569 m

INSIVUMEH reported that during 4-9 January Strombolian explosions at Pacaya’s Mackenney cone ejected material as high as 50 m above the main cone.

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

Popocatepetl, Mexico

19.023°N, 98.622°W, Summit elev. 5426 m

CENAPRED reported that at 1348 on 1 January an explosion at Popocatépetl generated a plume with low ash content that rose 0.5 km above the crater rim and drifted SE. Each day during 3-9 January there were 110-588 emissions, some of which contained minor amounts of ash. Beginning at 2032 on 6 January Strombolian activity generated an ash, gas, and water vapor emission that rose 800 m and drifted SE, and ejected incandescent material 200-300 m onto the flanks. Explosions were recorded at 0131 and 0222 on 8 January. The Alert Level remained at Yellow, Phase Two.

Geological summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 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 from Popocatépetl 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 precolumbian time.

Rincon de la Vieja, Costa Rica

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

OVSICORI-UNA reported that at 1758 on 9 January an eruption at Rincón de la Vieja produced a plume that rose 1 km above the crater rim.

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 that was 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 1916-m-high 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 3500 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.

Sabancaya, Peru

15.787°S, 71.857°W, Summit elev. 5960 m

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was similar to the previous week; there was an average of 41 explosions recorded per day during 1-7 January. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 3 km above the crater rim and drifted 50 km N, NW, and W. The MIROVA system detected nine thermal anomalies. The sulfur dioxide flux was high, at 3,409 tons per day on 5 January. The report noted that the public should not to approach the crater within a 12-km radius.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

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 29 December 2017-5 January 2018. On 10 January satellite images captured an ash cloud, 192x132 km in dimension, from explosions rising to altitudes of 10-11 km (32,800-36,100 ft) a.s.l. and drifting 230 km NE. KVERT raised the Aviation Color Code to Red. Later that day satellite images showed an ash cloud 350x180 km in dimension drifting 400 km E; the Aviation Color Code was lowered back to Orange.

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km 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.

Turrialba, Costa Rica

10.025°N, 83.767°W, Summit elev. 3340 m

OVSICORI-UNA reported that events at Turrialba at 0600 and 1319 on 8 January generated ash emissions that rose 400-500 m above the crater rim and drifted NW and NE, respectively. An event at 2005 generated an ash plume that rose 800 m above the crater rim and drifted SW. At 0630 on 9 January an ash plume rose 300 m above the crater rim and drifted SW. An event was recorded at 1412, though weather conditions prevented visual conformation.

Geological summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Source: GVP

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