SCEC Award Number 21055 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Resolving finite source attributes of moderate and small magnitude earthquakes of the 2019 Ridgecrest earthquake sequence
Investigator(s)
Name Organization
Wenyuan Fan University of California, San Diego
Other Participants
SCEC Priorities 1d, 2d, 4a SCEC Groups Seismology, FARM, SDOT
Report Due Date 03/15/2022 Date Report Submitted 08/07/2023
Project Abstract
Resolving earthquake rupture processes is essential for understanding earthquake physics and determining seismic hazards. However, it remains challenging to solve the finite-source attributes of moderate and small earthquakes directly; rupture processes of such events are traditionally resolved using spectral methods in the frequency domain. In this study, we apply a time-domain approach that makes minimal assumptions to measure apparent source time functions and measure the second-degree seismic moments of M 4 to 5.5 earthquakes from the 2019 Ridgecrest, California sequence. The second moments can characterize earthquake finite-source attributes, including the rupture length, width, duration, velocity, and directivity. The high-quality dataset offers an opportunity to quantitatively evaluate the uncertainties of the finite-source models. We aim to examine the impacts on the obtained source parameters from the model assumptions and data imperfections by performing a suite of statistical evaluations and estimating the extreme models. We compute and estimate of the earthquake static stress drop directly from the kinematic attributes and compare the results with frequency-domain estimates obtained using spectral analysis from a few prior studies to better understand the strengths and limitations of different approaches to source characterization.
Intellectual Merit This project focuses on determining the finite source attributes of moderate to small earthquakes, enhancing our understanding of their rupture processes. In addition, it provides a quantitative framework for examining the uncertainties associated with source attributes, furthering our understanding of the variabilities that can occur within a single fault system.
Broader Impacts This project partially supported postdoctoral scholars, Haoran Meng and Zhe Jia. In alignment with the larger community's endeavor to study earthquake source parameters, we collaborate closely with the stress-drop validation TAG, sharing and integrating our research efforts.
Exemplary Figure Figure 2.
Caption: Example of obtaining the apparent source time function (ASTF) using eGf deconvolution analysis.
(a) Observed and synthetic P waves, along with their associated ASTFs.
(b) Focal mechanism of the mainshock (Mw 5.4 example earthquake) and available eGfs.
(c) Example ASTFs of two stations, representing the forward and backward rupture directions.