Thursday, September 23, 2010
Tabulated New Zealand Earthquake Strong Ground Motions
This is absolutely fantastic! It shows the PGV and site class. 1 is solid rock, 4 is swamp. This is a table of all the available accelerometers. Nothing near the epicenter on firm ground, the nearest is at 84 km and gives 4 cm/s. Something on swamp near the quake gives 40cm/s! The nearest rock is 500 km away.
It's sad we won't learn too much about this quake. For that you need accelerometers on rock quite close. Then you can see how the rupture went, and if there was anything unusual, which I suspect.
For students, the main advice here is to be sure of your site when you plunk down an accelerometer. It is best to do a noise survey, or note local drilling results (n-values). The site classification from 1 to 4 is rather crude, but better than a kick in the head. Try very hard to locate on something solid. It can really pay off!