Friday, March 11, 2011


Some big events in Japan, as a huge 8.9 mag. earthquake shakes much of the island of Honshu. There was an associated tsunami that is washing across the Pacific. Callan Bentley has a good summary and intro to the events.

I was looking at the Hawaii seismic data - the newly formed Kamoamoa vent eruption appears to be waning and there's minimal incandescence visible on any of the webcams. The Hawaiian Lava Daily blog was mentioning that sea entry had stopped for now and he was waiting for earthquake swarms to point to where activity would re-emerge.

I had been poking around the HVO earthquake map and saw several small earthquakes just off the coast of Kalapana (where the lava had been pouring into the sea until last weekend). I tweeted a bit with Ron Schott (@rschott) about these quakes, and I think this could be related to bench collapses. As the lava pours into the sea, it cools - and forms an oversteepened slope or cliff. The quakes were a bit deep for this (10 km), but these are small quakes, so it could be related to problems in data resolution.

There was another fairly strong pair of quakes (3+) early this morning, before the tsunami, and the distribution of quakes still appears clustered around Kalapana.

Here's the whole-island view. You can see the flurry of seismic activity from the Kamoamoa event. It's still not enough data to really say what's going on, but I do find it interesting the majority of recent seismic activity has shifted to the coast (for now). If you will allow this paleobiologist to speculate on why - my first guess would be that there is some settling and "relaxing" related to the cessation of flow down the pali and into the ocean at Kalapana. I don't see it as foreshadowing new eruptive activity - but I could be totally wrong, I guess. It's happened before.

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