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| Titel |
Effects of 3D Earth structure on W-phase CMT parameters |
| VerfasserIn |
Catalina Morales, Zacharie Duputel, Luis Rivera, Hiroo Kanamori |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150241
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| Publikation (Nr.) |
 EGU/EGU2017-14679.pdf |
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| Zusammenfassung |
| The source inversion of the W-phase has demonstrated a great potential to
provide fast and reliable estimates of the centroid moment tensor (CMT) for
moderate to large earthquakes. It has since been implemented in different
operational environments (NEIC-USGS, PTWC, etc.) with the aim of providing
rapid CMT solutions. These solutions are in particular useful for tsunami
warning purposes. Computationally, W-phase waveforms are usually
synthetized by summation of normal modes at long period (100 – 1000 s) for
a spherical Earth model (e.g., PREM). Although the energy of these modes
mainly stays in the mantle where lateral structural variations are
relatively small, the impact of 3D heterogeneities on W-phase solutions
have not yet been quantified.
In this study, we investigate possible bias in W-phase source parameters
due to unmodeled lateral structural heterogeneities. We generate a
simulated dataset consisting of synthetic seismograms of large past
earthquakes that accounts for the Earth’s 3D structure. The W-phase
algorithm is then used to invert the synthetic dataset for earthquake CMT
parameters with and without added noise. Results show that the impact of 3D
heterogeneities is generally larger for surface-waves than for W-phase
waveforms. However, some discrepancies are noted between inverted W-phase
parameters and target values. Particular attention is paid to the possible
bias induced by the unmodeled 3D structure into the location of the W-phase
centroid. Preliminary results indicate that the parameter that is most
susceptible to 3D Earth structure seems to be the centroid depth. |
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