Surface Wave Tomography Across the Eastern North American Margin from Amphibious Data

Session: Amphibious Seismic Studies of Plate Boundary Structure and Processes
Type: Oral
Date: 4/29/2020
Time: 04:45 PM
Room: 120 + 130
Description: 

Measurements of surface wave dispersion have long been used to constrain shear velocities at lithospheric depths. Utilizing the period-dependent depth sensitivities of Rayleigh waves, we can image velocity structure at depths from the upper crust down to below the lithosphere-asthenosphere boundary. Deeper sensitivity is provided using long-period earthquake generated Rayleigh waves, while short-period ambient noise derived data are primarily sensitive to shallow, crustal structure. We have previously inverted ambient noise data across the Eastern North American Margin (ENAM) using onshore and offshore seismic instruments to produce maps of crustal velocity structure. In this study, we incorporate longer period earthquake Rayleigh wave data (up to ~120 seconds). Jointly inverting our previous ANT results alongside the longer period dataset, we create a 3D shear velocity model that spans the onshore and offshore components of the ENAM from ~10 to 200 km depth. Our results provide a high-resolution image of both crustal and lithospheric structures spanning from the cratonic interior of the US, across the margin, onto the oceanic portion of the North American plate. We observe sharp jumps in both crustal and lithospheric thicknesses across the margin. By jointly inverting both ANT and earthquake-generated data, we avoid many of the resolution-induced artifacts that can plague surface wave tomographic inversions by starting with a high-quality starting model for the crust to minimize the potential of artificially mapping spurious errors into shallow crustal depths.

Presenting Author: Colton Lynner

Authors