Resolving P-wave travel-time anomalies using seismic array observations of oceanic storms

Array analysis of seismic noise has the potential to be very useful in improving body-wave tomography of Earth structure, just as noise cross-correlation methods have recently proven successful in surface-wave tomography. Beamforming of seismic noise recorded in southern California reveals P-wave arrivals from distant storms in open oceans. In this case, the noise can be processed using cross-correlation among different station pairs and optimal P-wave relative arrival times can be estimated using the same approach traditionally used to analyze earthquake arrival times.Using three storms in the Gulf of Mexico, the Western Pacific (near Japan), and the South Pacific (near Fiji) respectively, we demonstrate that travel-time anomalies can be obtained from P waves generated by a distant storm, and that they are similar to those obtained from using an earthquake close to the storm. Our results suggest using oceanic storms as additional seismic sources for resolving P-wave travel-time anomalies.