Volcanic activity worldwide 7 May 2015: Turrialba volcano, Batu Tara, Bulusan, Sinabung, Hakone

Hakone (Honshu): An eruption warning has been declared for the volcano, as increased seismic activity under the Ōwakudani hydrothermal field were registered during the past days and could herald sudden phreatic explosions.
The Owakudani valley lies north of the central lava domes inside the Hakone caldera. Seismicity started to increase in late April, consisting mostly of swarms of shallow quakes at 2 and 5 km depth. More intense swarms have occurred during the past days, triggering the Japan Meteorological Agency (JMA) to raise the alert level of the volcano to 2.
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Simultaneously, slight deformation of the ground was detected and it appears that fumarolic activity has increased in the past days. Japanese authorities have closed access to the area, which is a popular tourist destination. After the deadly, sudden phreatic eruption of Ontake-san volcano last year, the risk of such eruptions has been taken very seriously.

Bulusan (Luzon Island, Philippines): (7 May) New, sporadic explosions have occurred at the volcano since 1 May, ejecting small plumes of ash. PHILVOLCS raised the alert level to 1 and an exclusion zone of 4 km around the volcano is in place.
According to the monitoring volcanologists, the activity has been phreatic in origin, i.e. caused by overheated ground-water rather than fresh magma at the surface.
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The first eruption was detected by its seismic signal and fine ash fall observed on the western and northwestern side of the volcano in the villages of Gulang-Gulang (6.5 km distance) and Sangjayron (11 km distance).
New ash emissions occurred last night. According to PHILVOLCS, an explosion from a vent on the northwestern slope of the volcano lasted 3:30 minutes and produced an ash plume that rose 250 m and drifted to the west. Ash falls occurred in the small town of Irosin, about 7.5 km southwest of the summit.


Batu Tara (Sunda Islands, Indonesia): Several ash plumes were detected on satellite imagery during the past days, suggesting a phase of elevated activity.

Sinabung (Sumatra, Indonesia): The lava dome and its viscous lobe continue to grow slowly at the summit. It is probably only a matter of time until new collapses again trigger potentially very dangerous.

Turrialba (Costa Rica): (7 May) A new series of weak to moderately powerful eruptions have occurred at the volcano during the past days.
A small and short ash eruption occurred on 1 May, with a plume of a few hundred meters height. On 4 May, a more intense eruption occurred at 13:20 local time, ejecting an ash column that rose 2.5 km and caused ash fall in areas of the Central Valley to the west, before drifting over the Pacific 100 km distance.
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During the eruption, several large bombs were ejected and fell several hundred meters from the crater.