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Surface waves, earth structure, and ...

Maceira, Monica.

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Surface waves, earth structure, and seismic discrimination.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Surface waves, earth structure, and seismic discrimination./
Author:	Maceira, Monica.
Description:	102 p.
Notes:	Adviser: Charles J. Ammon.
Contained By:	Dissertation Abstracts International67-08B.
Subject:	Geophysics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3231858
ISBN:	9780542843068

Surface waves, earth structure, and seismic discrimination.
Maceira, Monica.

Surface waves, earth structure, and seismic discrimination. - 102 p.

Adviser: Charles J. Ammon.

Thesis (Ph.D.)--The Pennsylvania State University, 2006.

To end, I implement and apply a method to jointly invert surface-wave group velocities and free-air gravity observations. (Abstract shortened by UMI.)

ISBN: 9780542843068Subjects--Topical Terms:

535228
Geophysics.

Surface waves, earth structure, and seismic discrimination.
LDR:03750nam 2200289 a 45 001 965869
005 20110908
008 110908s2006 eng d
020 $a 9780542843068
035 $a (UMI)AAI3231858
035 $a AAI3231858
040 $a UMI $c UMI
100 1 $a Maceira, Monica. $3 1288620
245 1 0 $a Surface waves, earth structure, and seismic discrimination.
300 $a 102 p.
500 $a Adviser: Charles J. Ammon.
500 $a Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4312.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2006.
520 $a To end, I implement and apply a method to jointly invert surface-wave group velocities and free-air gravity observations. (Abstract shortened by UMI.)
520 $a I compute short-period, high-resolution surface-wave slowness maps for central Asia using Bayesian tomography. I focus on the region between 69 and 108 degrees east and 29 and 54 degrees north and used seismograms from more than 1100 events. Using multiple-filter and phase-matched filter techniques, I measured the dispersion characteristics of the signals between 6 and 30 seconds period. These Rayleigh-wave group velocity dispersion curves were used to compute high-resolution, half-degree cell size, slowness tomographic maps. Because short periods are primarily sensitive to upper crustal structures, the images display low velocities associated with the Tarim, Junggar, and Qaidam basins. Relatively high velocities are associated with mountainous tectonic features such as the Tian Shan. I validated these maps using dispersion curves from 640 events that were not used to construct the tomographic model. The model predictions show a significant variance reduction at short and intermediate periods (6 to 15 s) with respect to the prior model. My model also shows 15% improvement in surface-wave detection capability with respect to previous 1D models. These high-resolution, short-period tomography maps can help improve regional magnitude estimations for construction of m b : Ms discriminants. Moreover, the short-period surface-wave tomographic results show unprecedented resolution that reveals greater geologic detail than has previously been achieved using surface waves, and which give us insight into the shear-velocity structure of the crust underlying this part of Asia.
520 $a I also validate an alternative method to the traditional m b - Ms seismic discriminant. This new technique uses a probability of detection model (PXD) to estimate the probability that a surface wave detection came from an underground explosion. I measured noise and signal levels of over 1,300 earthquakes and 26 underground explosions recorded at the broadband, digital station WMQ in western China. The PXD analysis shows a reduction of the false alarm rate from 22% to 17% for this dataset. Using path-dependent attenuation and the previously computed group velocity values, the false alarm rate decreases even more to 15%. I also present a new procedure to accurately make Rayleigh wave amplitude measurements and I compute new surface wave magnitudes, Ms, following the methodology of Marshall and Basham and the methodology of Russell. The new Ms computed following Russell´s formulation proved to be an effective mb - M s discriminant and do not require farther analysis with the probability of detection model. This finding is of great importance to seismologists working on seismic discrimination problems.
590 $a School code: 0176.
650 4 $a Geophysics. $3 535228
690 $a 0373
710 2 0 $a The Pennsylvania State University. $3 699896
773 0 $t Dissertation Abstracts International $g 67-08B.
790 $a 0176
790 1 0 $a Ammon, Charles J., $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3231858