
A magnitude 5.6 earthquake just struck directly beneath Mount Fuji — JMA puts the follow-up probability at 10-20% and the monitoring window at 7 days. The 1707 precedent took 49.
JMA confirmed no changes in volcanic monitoring data after the June 26th M5.6 at 20km depth near Fujikawaguchiko. The agency issued a standard one-week caution window citing 10-20% historical frequency of comparable follow-up events.
The part missing from most coverage: the 2012 NIED study estimated magma chamber pressure beneath Fuji at 1.6 MPa following the Tōhoku earthquake — 16x the 0.1 MPa threshold associated with the 1707 Hōei eruption, which occurred 49 days after the M8.6 Nankai earthquake, well outside the standard monitoring window.
Full analysis with sources: https://youtu.be/l0A7xswu1sM?is=68d-VS0lv6j3tvTt