northanger (northanger) wrote,
northanger
northanger

Weekly Volcanic Activity Report

Weekly Volcanic Activity Report

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New Activity/Unrest

KRAKATAU Indonesia 6.10°S, 105.43°E; summit elev. 813 m; All times are local (= UTC + 7 hours)

On 13 April at 0800, DVGHM raised the Alert Level at Krakatau to 2 (on a scale of 1-4).

Background. Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed 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 volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927.

map

TALANG Sumatra, Indonesia 00.98°S, 100.68°E; summit elev. 2,896 m; All times are local (= UTC + 7 hours)

On 12 April during 0340-0600, an eruption at Talang produced an ash plume that rose to a height of ~1 km above the crater (~12,800 ft a.s.l.). About 4 mm of ash fell in the village of Bukit Sileh, NE of the volcano. The Alert Level was raised to 4, the highest level. News articles reported that thousands of residents near the volcano evacuated. Several days prior to the eruption, a "gray ash cloud" was visible rising to ~100 m above the volcano's summit (9,800 ft a.s.l.).

On 13 April volcanic and seismic activity decreased in comparison to the previous day. A "white-gray ash plume" rose 250 m (10,300 ft a.s.l.) above Kawah Mati crater, and gas was emitted from Gabuo Atas crater. There was a decrease in the number of deep volcanic, shallow volcanic, and explosion earthquakes. Talang remained at Alert Level 4.

Background. Talang, which forms a twin volcano with the extinct Pasar Arbaa volcano, has two crater lakes on its flanks. The largest of these is 1 x 2 km wide Danau Talang. No historical eruptions have occurred from the summit of the volcano, which lacks a crater. All historical eruptions from Gunung Talang volcano have involved small-to-moderate 19th-century explosive activity originating from a series of small craters in a valley on the upper NE flank.

map

TANGKUBANPARAHU western Java, Indonesia 6.77°S, 107.60°E; summit elev. 2,084 m; All times are local (= UTC + 7 hours)

On 13 April at 0700 DVGHM raised the Alert Level at Tangkubanparahu to 2 (on a scale of 1-4) due to an increase in seismicity at the volcano. In addition to an increase in seismicity in comparison to the previous day, there was a strong scent of sulfur near Ratu crater. On the 13th at 1300 the Alert Level was raised to 3 due to a further increase in seismicity and the occurrence of tremor. No ash plume was observed. Visitors were banned from the summit and crater area.

Background. Tangkubanparahu is a broad shield-like stratovolcano overlooking Indonesia's former capital city of Bandung that was constructed within the 6 x 8 km Pleistocene Sunda caldera. The volcano's low profile is the subject of legends referring to the mountain of the "upturned boat." The rim of Sunda caldera forms a prominent ridge on the western side; elsewhere the caldera rim is largely buried by deposits of Tangkubanparahu volcano. The dominantly small phreatic historical eruptions recorded since the 19th century have originated from several nested craters within an elliptical 1 x 1.5 km summit depression. Tangkubanparahu last erupted in September 1983, when ash rose up to 150 m above the rim of Kawah Ratu.

map

Subscribe
  • Post a new comment

    Error

    Anonymous comments are disabled in this journal

    default userpic

    Your reply will be screened

  • 0 comments