Just happened to see a 6.6 quake hit the Aleutians less than an hour ago and it got me to thinking. Historically, quakes from around that island chain have put Hawaii on tsunami alert and have actually caused tsunamis. So have quakes from around Chile.
Looking at the globe, however, it seems like the real threat would come from quakes around California, yet I’ve never heard of a tsunami alert based on a quake in that area. I can’t think of any reason why that should be, unless it is because quake epicenters in California tend to be on land, not in the ocean, so the amount of energy being dissipated in the water is less?
Fight my ignorance, please.
Tsunamis are caused by a section of water being displaced rapidly, usually in a tectonic subduction
zone, which is where one tectonic plate is slipping underneath another one.
The San Andreas fault is a transform plate boundry which means two tectonic plates are slipping past each other horizontally like two boats scraping each other’s sides as they pass too closely. This doesn’t displace much water and doesn’t cause tsunamis (it does extend out into the ocean … I think).
I don’t think Californian quakes are going to cause too many tsunamis, but California has been hit by a lot of tsunamis that were triggered elsewhere. Many of them were small and caused no damage, but northern CA is pretty vulnerable to tsunamis created by Alaskan and Aleutian earthquakes. There are also areas of vertical slippage in the Cascadia subduction zone off California’s northern coast which could cause a tsunami, but there isn’t much action going on there. Most of the earthquakes happen along the San Andreas.
Beach front real estate is overrated.
Really.