title: Antipodal focusing of seismic waves observed with the USArray.
abstract: We present an analysis of theMw= 5.3 earthquake that occurred in the Southeast Indian Ridge on 2010 February 11 using USArray data. The epicentre of this event is antipodal to the USArray, providing us with an opportunity to observe in details the antipodal focusing of seismic waves in space and time. We compare the observed signals with synthetic seismograms computed for a spherically symmetric earth model (PREM). A beamforming analysis is performed over the different seismic phases detected at antipodal distances. Direct spatial snapshots of the signals and the beamforming results show that the focusing is well predicted for the firstP-wave phases such as PKP orPP. However, converted phases (SKSP,PPS) show a deviation of the energy focusing to the south, likely caused by the Earth's heterogeneity. Focusing of multipleS-wave phases strongly deteriorates and is barely observable.
authors.affiliation: IPGP, Sorbonne Paris Cité, CNRS (UMS 7154), Paris, France. E-mail: retailleau.lise@gmail.com ; CEA/DAM/DIF, F-91297 Arpajon, France.
authors.forename: L
authors.initials: L
authors.lastname: Retailleau
authors.affiliation: IPGP, Sorbonne Paris Cité, CNRS (UMS 7154), Paris, France. E-mail: retailleau.lise@gmail.com.
authors.forename: N M
authors.initials: NM
authors.lastname: Shapiro
authors.affiliation: CEA/DAM/DIF, F-91297 Arpajon, France.
authors.forename: J
authors.initials: J
authors.lastname: Guilbert
authors.affiliation: Institut des Sciences de la Terre, CNRS, Université Joseph Fournier, Grenoble, France.
authors.forename: M
authors.initials: M
authors.lastname: Campillo
authors.affiliation: Institut des Sciences de la Terre, CNRS, Université Joseph Fournier, Grenoble, France.
authors.forename: P
authors.initials: P
authors.lastname: Roux
keywords: Body waves; Earthquake source observations; Wave propagation