Temporal and spatial evolution of an on-land hurricane observed by seismic data

Abstract

A dense seismic array can provide new perspectives for a decaying hurricane after its landfall. The case of Hurricane Isaac in 2012 is presented using a seismic array from EarthScope (USArray). The amplitude-distance plots from the center of the hurricane showed a sharp peak at a distance of 75 km at the time of landfall. This peak decayed and moved outward from the center over the next 1.5 days. The sharp peak can be explained by strong surface pressure fluctuations under the eyewall in which a focused ascending flow is known to exist. We reconstructed the time evolution of surface pressure that explains seismic data. Pressure solutions indicate that the eyewall stayed at 75 km in the first 10 h after the landfall, while the ascending flow weakened significantly. In the following 24 h, the eyewall diffused and moved to distances about 200-300 km, suggesting its collapse during this period. Key Points Hurricane eyewall can be studied from seismic amplitude versus distance plotsSeismically derived surface pressure shows the location and strength of eyewallTime evolution of this decaying process can be tracked