Propagation of Symmetric Mode Lamb Waves from the Grounded Margins of the Ross Ice Shelf in Response to Teleseismic S-Wave Arrivals

Session: Environmental and Near Surface Seismology: From Glaciers and Rivers to Engineered Structures and Beyond [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

An ice shelf is mechanically equivalent to a floating elastic plate that is elastically and gravitationally coupled to the underlying ocean and, at its grounded points, to the solid Earth. Ice shelves thus support a spectrum of elastic and gravitational flexural modes that are not encountered in solid Earth seismology. A symmetric mode Lamb wave is a laterally propagating elastic plate wave with longitudinally polarized displacements across the full thickness of the plate. It has previously been observed that symmetric mode Lamb waves in the Ross Ice shelf are excited by ocean forcing at the ice front and by slow ice stream earthquakes along the Siple Coast. Using data from the RIS/DRIS broadband seismic network deployed across the Ross Ice Shelf from 2014 to 2016, we show that symmetric mode Lamb waves are also commonly excited at the grounded margins of an ice shelf by the arrival of teleseismic S-waves. These Lamb waves are narrow band and show waveform similarity with the incoming solid Earth S-waves. These signals are observed as far as 250 km into the ice shelf interior. The various modes of excitation and the efficient propagation of these Lamb waves suggest potential applications for tomographic interrogation of ice shelves at large scales.

Presenting Author: Michael G. Baker

Authors