Numerical simulations of T-wave generation and conversion at shores: Influence of slope angles and of the SOFAR channel

• Published in: The Journal of the Acoustical Society of America Vol. 141; no. 5; p. 4045
• Main Authors: Bottero, Alexis, Cristini, Paul, Komatitsch, Dimitri
• Format: Journal Article
• Language: English
• Published: 01.05.2017
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4989349

The term T waves is generally associated to acoustic signals generated by earthquakes which end up traveling horizontally in the ocean at the speed of sound in the water. After traveling over long ranges they reach the shore, where they can be reflected or converted into (visco)elastic waves. For almost 90 years, T waves have been the subject of numerous studies in order to identify their generation mechanisms. Generally, it is supposed that seismic waves are converted to horizontally propagating T-waves by a sloping sea bottom before entering the SOFAR channel. In this study, we present a two-step parametric study of the influence of the slope on a typical T-wave generation/conversion scenario. We use a 2D spectral-element method that allows for full-waveform modeling of wave propagation. In a first step we study the amount of acoustic energy channeled from a deep earthquake below a sloping sea-floor. We then model the reflection/transmission of T waves at the shore. Our results suggest that an optimum slope angle exists for T-wave generation, and that a non-negligible amount of the channeled energy can be reflected at a sloping shore. We find no evidence of a significant influence of the SOFAR channel.