Friday, April 21, 2017

A home mountain stirs in its sleep

Volcanic earthquakes detected under Hakusan

NHK Kanazawa reports that, on 20 April, more than 40 small earthquakes occurred under Hakusan - the volcano in Japan's Hokuriku district best known as the home mountain of the Hyakumeizan author. One tremor of magnitude 2.2 occurred near the summit at 1.30 am. Bursts of seismic activity are not unusual under long-dormant volcanoes: on 1 December 2014, more than 150 small tremors were detected in the same area.

The title of this magazine article reads: "X-day for the looming Hakusan eruption".
Well, maybe not quite yet....
According to Wikipedia, the bulk of Hakusan dates back to eruptions that happened 30,000-40,000 years ago. In those days, the edifice may have been higher than Mt Fuji. In a kind of coda to the main action, Ken-ga-mine, a subsidiary summit, welled up as a lava dome about 2,000 years ago. Hakusan most recently erupted in 1659. Eruptions were also recorded in 1554, 1042 and 706 – the earliest one taking place just over a decade before Monk Taichō made the mountain's first ascent.

In yesterday’s episode, the type of low-frequency tremors that signal the movement of magma or volcanic gases was absent, suggesting that an eruption is probably not imminent. So it’s unlikely that the 1,300th anniversary of Taichō’s ascent, which falls this summer, will be marked or marred by a volcanic outburst.