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Article Dans Une Revue Geophysical Journal International Année : 2020

Impact of 3-D Earth structure on W-phase CMT parameters

Résumé

We investigate the impact of un-modeled 3D structural heterogeneity on inverted W-phasesource parameters. We generate a large dataset of synthetic seismograms accounting for theEarths 3D structure for 250 earthquakes globally distributed. The W-phase algorithm is thenused to invert for earthquake CMT parameters, assuming a spherical Earth model. The im-pact of lateral heterogeneity is assessed by comparing inverted source parameters with thoseused to compute the 3D synthetics. Results show that the 3D structure mainly affects centroidlocation while the effect on the other source parameters remains small. Centroid mislocationspresent clear geographical patterns. In particular, W-phase solutions for earthquakes in SouthAmerica are on average biased 17 km to the East of the actual centroid locations. This ef-fect is significantly reduced using an azimuthally well balanced distribution of seismologicalstations. Source parameters are generally more impacted by mantle heterogeneity while thescalar moment of shallow earthquakes seems to be mainly impacted by the crustal structure.Shallow earthquakes present a variability ofMrθandMrφmoment tensor elements, result-ing both from the small amplitude and a larger uncertainty of the associated Green’s functions.
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hal-03032581 , version 1 (28-08-2021)

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Catalina Morales-Yáñez, Zacharie Duputel, Luis Rivera. Impact of 3-D Earth structure on W-phase CMT parameters. Geophysical Journal International, 2020, 223 (2), pp.1432-1445. ⟨10.1093/gji/ggaa377⟩. ⟨hal-03032581⟩
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