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Berg, Elizabeth

Publications and source records attributed to Berg, Elizabeth.

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Unraveling the Wrinkle in Time-Variable Sources with Lunes and Synthetic Seismic Data

In this report, we describe how to estimate the time-variable components of the seismic moment tensor and compare these estimates to the more conventional analysis that incorporates an assumption of the source time function (STF) across all components of the seismic moment tensor. The advantage of our method is that we are able to independently estimate the time-evolution of each component of the seismic moment tensor, which may help to resolve the complex source phenomena associated with buried explosions. By performing an eigen decomposition of the time-evolving seismic moment tensor components, we are able to plot the seismic mechanism as a trajectory on a lune diagram. This technique enables interpretation of the seismic mechanism as a function of time, as opposed to the more conventional analysis which assumes that the seismic mechanism is time invariant. Finally, we describe the differences between the seismic moment and the seismic moment rate STFs, how to implement each one in inversion schemes, and the relative strengths/weaknesses of each. Our key take-away is that we are able to distinguish nearly-overlapping sources with highly different mechanisms, such as an explosion immediately following an earthquake, by estimating moment rate from seismic data through a STF-invariant inversion for the full time-variable moment tensor.

58 GEOSCIENCES↗
DOE OSTI2022

A Geophysicist's Guide to the Fairfield Nodes

This report details how to successfully use the Fairfield Nodal ZLand seismic instruments to collect data, including preparation steps prior to deploying the instruments, how to record data during a field campaign, and how to retrieve recorded data from the instruments after their deployment. This guide will walk through each step for the novice user, as well as provide a checklist of critical steps for the advanced user to ensure successful, efficient field campaigns and seismic data collection. Currently, use of the seismic nodal instruments is highly limited due to the detailed nature and prior knowledge required to successfully set up, use, and retrieve data from these instruments. With this guide, all interested users will have the knowledge required to perform a seismic deployment and collect data with the Fairfield Nodal instruments.

47 OTHER INSTRUMENTATION↗