IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS011 Poster presentation 2183
Comparison of Long Period Normal Modes from the Sumatra Earthquake
Using Superconducting Gravimeters and GSN Seismometers
Prof. David Crossley
Earth and Atmospheric Sciences Saint Louis University IAG
Yan Xu
We have analyzed the available superconducting gravimeter (SG) data from the Sumatra earthquake of
2004, and compared it to similar data from seismometers of the GSN network. Our goal was to
determine whether SG data can add information about the Earth through the refinement of parameters
such as seismic Q and M0, the seismic moment of the earthquake, the latter through its effect on
normal mode amplitudes. SGs are known to have very good amplitude calibration (0.01-0.1%), and SG
data is now becoming available through IRIS for the use of the seismic community. Our results to date
show that the determine of the Q factor of modes such as 0S0 is very good, but there are difference in
the amplitudes determined from SGs and seismometers that may, or may not, be due to calibration
effects. We will show a comparison between theoretical and observed amplitudes for low frequency
modes in the range 0.3-2.0 mHz..
Keywords: normal modes, superconducting gravimeters, sumatra