Monday, August 03, 2009

Did you feel today's quake?

As of 3 pm today, the USGS has received 825 reports from 220 zip codes and 11 cities, of shaking from the M 6.9 earthquake this morning. You can report directly to the USGS.

But Bob Anderson with the Calif. Seismic Safety Commission called a while ago, asking if we could help with an engineering study they are doing. They are examining long period seismic waves and their impacts on tall buildings, especially those 16 stories and more.

Here in Tucson, we've heard it was felt in the 12 story Unisource building and on the top story (5th floor) of the State Office Complex next to us.

If you felt the quake today can you let us know what kind of building you were in and what happened? In particular CSSC is looking for information on:
  • building height (in feet or stories)
  • building construction type
  • soil type (eg sand and gravel, valley fill, bedrock, etc)
  • effects (eg damage, cracks, things moved, alignments changed, etc)
  • duration of shaking (eg, 3 seconds)
We have very little real data on engineering seismology or strong motion effects, because our large earthquakes in Arizona occurred before modern equipment was available and installed to record the results.

We may be able to learn something from this event that will help prepare us for an earthquake closer to home.

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