Sunday, July 17, 2016
Always the chance of big offshore earthquakes
A very weird M3.7 earthquake off Florida the other day. This is just a reminder that our 'passive margin' can be quite active. The ocean crust gets colder, and sediments from the interior just pile on. In another 100 million years or so, the basaltic ocean crust starts to plunge, and the next thing you know we have a subduction zone. Just another day with the Wheel of Plate Tectonics.
Anyway, all the cities along the passive margin share the same odds as any other earthquake, of about 1 in 500 per year of a devastating earthquake. And these cities have very old brick brownstones on swamp, I just stayed in one in NYC. So, if you are the totally paranoid type, check your foundation, if you are in a multi-story old brick building. This is best done by my handy-dandy accelerometer, doing a noise test. Or you can check around at people installing fencing. Since nobody will ever do this, I don't worry about mass-producing my device, or even making a working version. :)
Embarassing footnote: A navy test explosion. Still, everything above is true. :(