An Overview of the Rock Valley Direct Comparison Project
Description:
How do we identify the cause of seismic energy from the signals themselves? We currently have a variety of empirical methods to distinguish explosions from earthquakes, cavity collapses, and other types of events. Recent work using local distance (<200 km) data have revealed new challenges, however, and there remains uncertainty in our understanding of the underlying physics because so many different variables (e.g., propagation, depth, medium properties, source time function, mechanism) are in play. To evaluate source differences alone, we plan to compare, for the first time, a co-located chemical explosion to a shallow earthquake in the Rock Valley Direct Comparison (RV/DC) project.
The RV/DC takes advantage of the 1993 shallow earthquake sequence in Rock Valley on the Nevada National Security Site (the former Nevada Test Site). The largest event, M3.7, was followed by eleven M>2 events ranging in depth from 1-3 km. All are well constrained due to the deployment of temporary stations early in the sequence. We will conduct two chemical explosions at similar hypocenters to the earthquakes to understand the discrimination features between these types of events. We have systematically relocated the 1993 events, varying velocity models and codes, but using a common pick data set to choose the experiment borehole location. Three additional boreholes are planned and will be instrumented to obtain microseismicity data, sample fault properties, and record the chemical explosions. We are installing a dense surface seismoacoustic network, including re-occupying stations that recorded the 1993 earthquakes. A geologic framework for modeling and predicting synthetic both earthquake and explosion waveforms is being developed in advance of the actual explosions. We believe this exciting effort will reveal new insights into discriminating explosions from a background of earthquakes, as well as provide novel information about the physics of earthquakes themselves.
Prepared by LLNL under Contract DE-AC52-07NA27344. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Session: Exploiting Explosion Sources: Advancements in Seismic Source Physics
Type: Oral
Date: 4/19/2023
Presentation Time: 02:15 PM (local time)
Presenting Author: William R. Walter
Student Presenter: No
Invited Presentation:
Authors
William Walter Presenting Author Corresponding Author walter5@llnl.gov Lawrence Livermore National Laboratory |
Catherine Snelson snelsonc@lanl.gov Los Alamos National Laboratory |
Robert Abbott reabbot@sandia.gov Sandia National Laboratories |
Cleat Zeiler zeilercp@nv.doe.gov Nevada National Security Site |
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An Overview of the Rock Valley Direct Comparison Project
Category
Exploiting Explosion Sources: Advancements in Seismic Source Physics