Tsunami Risk Higher in Los Angeles, Other Major Cities Than Thought, Haiti Study Suggests

[AsahinaKimi]

Geologists studying the Jan. 12 Haiti earthquake say the risk of destructive tsunamis is higher than expected in places such as Kingston, Istanbul, and Los Angeles.

Like Haiti's capital, these cities all lie near the coast and near an active geologic feature called a strike-slip fault where two tectonic plates slide past each other like two hands rubbing against each other.

Until now, geologists did not consider the tsunami risk to be very high in these places because when these faults rupture, they usually do not vertically displace the seafloor much, which is how most tsunamis are generated. This latest research suggests even a moderate earthquake on a strike-slip fault can generate tsunamis through submarine landslides, raising the overall tsunami risk in these places.

"The scary part about that is you do not need a large earthquake to trigger a large tsunami," said Matt Hornbach, research associate at The University of Texas at Austin's Institute for Geophysics and lead author on a paper describing the research in the Oct. 10 online edition of the journal Nature Geoscience.

http://www.sciencedaily.com/releases/2010/10/101010133626.htm

[dipsydoodle]

1. I've seen a TV documentary about this here in the UK

The CA coastal strips would only have a 10 minutes warning in the event of a slip just out at in the ocean.

[AsahinaKimi]

2. A tsunami has always been my biggest nightmare..

You can't step out of its way.. you can go to higher ground, but if its huge, the ground would not be high enough.

[necso]

3. If the reader examines

the maps in the following links, there's an indication (in SoCal) of offshore faulting similar to the three big parallel-fault-complexes of the San Andreas, San Jacinto, and Elsinore. If generated close to shore, tsunami-waves would have little distance to dissipate. (Of course, it's more complicated than that: eg, there must be a significant driver (like significant movement of tectonic elements, accumulated sediments), a significant shock to the seawater.)

http://earthquake.usgs.gov/earthquakes/recenteqscanv/

http://earthquake.usgs.gov/earthquakes/recenteqscanv/FaultMaps/117-33.html

Digressing, a little to the east of the last map is an interesting feature ("Elmore Ranch") of perpendicular faults (roughly perpendicular to the parallel faults) near (under?) the south Salton Sea. Not all faults necessarily show on the map; and earthquake data can point to additional features.

http://earthquake.usgs.gov/earthquakes/recenteqscanv/FaultMaps/116-33.html