Volcanic news of the week: Hakone, Villarica, Sinabung

The alert level of Hakone volcano, on the island of Honshu in Japan,  was raised to 2, following an increase in seismic activity on 6 may ; 140 volcanic earthquakes were recorded by the JMA, including two of magnitude 2.0 and 2.4. On May 5, three minor earthquakes shook the city of Hakone Yumoto, while steam was observed at around Owakudani hot springs, popular site visited by tourists, who go there to consume a local specialty, Kuro- tamago, eggs cooked in hot springs, with blackened shells, supposed to increase longevity.

On Monday, four major trails had been closed by the operators of the Hakone Ropeway; the road to Owakudani was closed today, and a 300 meters radius area evacuated. The Owakudani valley, whose name means " Great boiling valley  ", is part of the Hakone chain; it was formed there about 3,000 years during an eruption of the volcano.

(Views of Japan)

The Hakoneyama is truncated by two  overlapping  calderas, the largest 10 km of 11, formed during major eruptions  there are 180,000 and 49,000 to 60,000 years. Lake Ashi  is between the southwest wall of the caldera and a half dozen of post-caldera lava domes;  they was formed subsequent to the formation of a dam on Hayakawa Valley, following  an eruption and a collapse 3,000 years ago. The last identified  eruption of the Hakone volcano concerns Owakudani and is dated  from the 1170 ± 100 year. (Global Volcanism Program - Hakoneyama)

In Chile, the Villarica has a permanent nocturnal glow, accompanied by a throbbing, diffuse degassing. The volcanic system shows a stable trend, with little or no strombolian activity ... however the alert level remains at orange / probable eruption in terms of days or weeks, with a restriction zone of 5 km around the crater and hazardous areas defined by 200 meters either side of drainage, for possible lahars having the ability to move at speeds of around 100hm / h.

Usual activity at the Sinabung / Sumatra … the active reconstruction cycle of the lava lobe after collapse and pyroclastic flow continues.