May 2015 – JAPAN – The number of volcanic earthquakes recorded in Hakone, Kanagawa Prefecture, surged Tuesday, with 98 recorded before 3 p.m. compared with 34 for all of Monday, the Meteorological Agency said. The agency said it still believes the possibility that the Hakone volcano will erupt is low, and it is maintaining the alert level at 1 on the scale of 5. Level 1 means “normal.” However, hot steam could suddenly be expelled from the ground in or near the popular Owakudani Valley, the agency warned, urging people not to enter areas designated as off-limits. “Shallow hot-water activity in parts of the Owakudani Valley has become unstable,” the agency said in an advisory. “There is a possibility that a minor ejection (of hot steam) may suddenly occur,” it said. “Please do not enter danger zones.”
The warning, which comes in the middle of the Golden Week spring holidays, is expected to affect tourism there as some 20 million people, including many foreign tourists, visit the scenic area on an annual basis. It is one of the country’s most famous hot-spring resorts. Of the quakes Tuesday, two that shook the area between 6 a.m. and 7 a.m. were strong enough to be felt. They registered level 1, or the lowest, on the Japanese intensity scale of 7, the agency said. The focus of both was about 10 km underground. Local officials have barred visitors from entering recreational trails and hiking courses in the valley. The number of volcanic quakes began to surge April 26, though only two were recorded last Friday. However, 37 earthquakes were recorded Saturday, followed by 36 on Sunday and 34 on Monday. According to Volcano Discovery, the last activity of Hakone volcano was ca. 800 years ago and consisted in phreatic explosions. –Japan Times
An aerial photo taken from Kyodo News helicoptor shows steam rising the ground in Hakone-machi, Kanagawa Prefecture. The Japan Meterological Agency said the number of volcanic earthquakes in Hakone on Tuesday reached 116, the highest ever recorded in one day.
Alert level raised on Mount Hakone Volcano
(Update filed – May 6, 2015) Japanese authorities raised the volcano alert for Mount Hakone, a popular tourist spot southwest of Tokyo, on Wednesday morning, anticipating a possible small eruption that could impact the nearby Owakudani hot spring district and calling on people to stay away from potentially dangerous areas. The alert has been raised from 1, which denotes normal levels, to 2, a level that regulates entry to areas around the volcanic vent, the Japan Meteorological Agency said. The number of volcanic earthquakes there on Tuesday reached 116, the highest ever recorded in one day, the agency said. The local town office issued an evacuation order for a 300-meter radius around Owakudani and closed the road leading to the area. It revised the evacuation area from the initially announced 700 meters.
The operator of Hakone Ropeway suspended a portion of its service running through Owakudani. Caution is advised over ash deposits and rocks that could rain down on the area if an eruption occurs. Seismic activity has been increasing since April 26 in the Mount Hakone region, a popular spot for tourists and hikers in Kanagawa Prefecture, with tremors originating from areas around Owakudani. On Tuesday, three minor earthquakes were reported in Hakone-Yumoto, while active steam bursts were also observed at hot spring facilities in Owakudani, leading the authorities to believe volcanic activity is intensifying.
Meteorological agency officials have become more concerned after the last of the three tremors was focused deeper than the earlier ones, raising the possibility of a steam eruption. A geological survey of Mount Hakone has suggested that there was an eruption in the 12th century near Owakudani, but there has been no record of subsequent eruptions in the area. Volcanic activity in Hakone last increased notably in 2001, causing minor quakes and crustal deformation for about four months. –Japan Times