Wednesday, November 27, 2013

Seismic Death Traps of the World - Lima, Peru

Just in time for Christmas, I have started a new series, which may end at one.

According to this article, the situation is bad.  Lucky for us, I can't extract very much from behind the pay-wall, but I'll take it that most of the foundations are loose alluvial deposits.  Now, Lima has been exposed to many earthquakes over the last decades, but no big one that can produce a steady 20 cm/s, which would amplify 10 to 100 times on the deep soil basins.

We can just use the available resources.

Here is a picture of the general geology.

Look at that beautiful, sharp, gently curved subduction zone.  With all the sediment washing off the Andes, that has to go with an M9 every few hundred years.  That last happened in 1746, just after our famous Cascadia event.  But this is 10 times cleaner than Cascadia.  I usually put these at 500 years, so maybe Lima can catch a break.

The terrain map is very Los Angeles.

That means there are only unstable dirt mountains, or deep dirt valleys.  The only water comes from a single buried river.

The buildings are quite modern, since anything too bad has been destroyed many times over.

This is near the coast.  This building will be flat, but there are modern standard apartment buildings nearby.  It all depends on the quality of construction.

Right on the coast, we don't expect much.

These fine buildings will not be happy with a 50 foot wall of water, but they'll get an hour, and they look rich enough.  They probably never live in the places anyway.  :)

No comments: