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Amphibious Receiver Function Imaging of the Pacific Plate Using Tuned Dereverberation Filters

Session: Amphibious Seismic Studies of Plate Boundary Structure and Processes [Poster]

Type: Poster

Date: 4/20/2021

Presentation Time: 04:15 PM Pacific

Description: 

The Alaska Amphibious Community Seismic Experiment (AACSE) presents a unique opportunity to conduct high-resolution seismic imaging of the lithosphere-asthenosphere system of the Pacfic plate prior to subduction, and investigate the role that temperature, or hydration plays in influencing sharp seismic discontinuities detected at the bottom boundary layer of the plate as it ages to ~40-60 Myrs. A popular tool for high-resolution seismic imaging of the oceanic plate is the receiver function (RF) method which is specifically suited for detecting sharp subsurface discontinuities close to and beneath a seismic station. When the technique is applied to land-based stations near a subduction zone, or ocean bottom stations (OBS) buried in a borehole, the RF approach is less susceptible to instabilities caused by signal-generated noise from two well-known sources: (1) strong reverberations in the overlying ocean layer, and (2) trapped waves within the underlying sediments. Both cases do not apply to the OBS stations in the AACSE network. Recent work shows how stable high-resolution receiver function imaging of the oceanic lithosphere can be obtained using dereverberation filters designed to eliminate the water and sediment reverberations that hamper the detection of subsurface discontinuities. Here, we apply an extension of their approach to the 75 OBS stations in the AACSE array. Since these stations are deployed across the trench into the deep oceans, we quantify the relationship between the observed resonances and the ocean depth and sediment properties across the array, using a multi-taper spectral coherence approach. By tuning the parameters of our dereverberation filter to the spectral peaks and implementing a stacking approach that improves time-domain semblance and coherence of migrated receiver function, we expect to improve detection of seismic discontinuities across the AACSE array.

Presenting Author: Ziqi Zhang

Student Presenter: Yes

Authors