HR: 1330h
AN: S32A-0837    [PDF]
TI: Illuminating the Socorro Magma Body from Below using Deep Teleseismic Events
AU: * White, T A
EM: twhite@ees.nmt.edu
AF: Department of Earth an Environmental Sciences, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AU: Schlue, J W
EM: schlue@nmt.edu
AF: Department of Earth an Environmental Sciences, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AB: The Socorro Magma Body (SMB) is a large, sill-like magma body located $\sim$19 km beneath Socorro, NM. The SMB was discovered in 1962, and its current areal extent (\raisebox{-0.24ex}{$\stackrel{\scriptstyle<}{\scriptstyle \sim}$}5000 $km^{2}$) was mapped in 1979, using reflected phases from the local events whose hypocenters were shallower than the SMB itself. Investigating the interior of the SMB is difficult, both due to the large impedance contrast between the upper SMB and the host rock, which severely limits the energy that can be transmitted into it from above, and because of its apparent thinness. Previous work using modeling of stacked, reflected P phases from shallow microearthquakes associated with the magma body has estimated a thickness of $\sim$130 m for the SMB, while a receiver function study obtained estimates for a thickness of 50 m and an S-wave velocity of 0.4 km/s (both with large error bounds). In this study, we attempt to better characterise the interior of the SMB using normalized amplitude spectra of teleseismic P-waves. We currently have digital waveforms of P phases from more than 30 deep ($>$200 km) teleseismic events collected by the local network of vertical, short period seismometers. Finite element analysis will be used to model the SMB and to find a best fit to the spectral signatures. This work is ongoing; however, preliminary results of simple modeling of the SMB using Kennett's 2-D wave propagation method shows promising similarities with the averaged spectral signature.
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1242)
DE: 7260 Theory and modeling
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2003 Fall Meeting