Research

I use a variety of seismological methods to analyze earthquakes source spectra and catalogs. Methods include: statistical modeling, empirical Green's function, waveform cross-correlation, earthquake clustering, focal mechanism.

I am currently working on analyzing induced seismicity in the central US, geothermal induced seismicity in California, source parameter validations and repeating earthquakes in the Parkfield segment in central California. Some example projects are included.

My future research will include:

(1) dense array observations of microearthquakes

(2) induced earthquakes (geothermal or hydraulic fracturing)

(3) environmental seismology

(4) subsurface structure from reflectivity.

In 2021, we will be installing a temporary Distributed Acoustic Sensing (DAS) array in northern Oklahoma, the purpose of the array is to investigate ground motion induced by extreme weather events and microearthquakes. An introduction of this array is included in this video: https://www.dropbox.com/s/lgxevi3iupobm9i/Xiaowei_DAS_OU.mp4?dl=0

The triggering process of the M5.8 Pawnee earthquake

The M5.8 Pawnee earthquake resulted from the interaction among injection, faults, foreshocks, which is similar to plate boundary earthquakes. This indicate that the common processes we observe for tectonic earthquakes can happen to induced earthquakes (Chen et al., 2017, Scientific Reports).

Small earthquakes can be very complex

We normally regard small earthquakes as relatively simple. However, with dense recordings, we find a Mw4.1 involved four sub-events during its rupture process (Wu et al., 2019, GRL). Previous studies have been focused on large earthquakes, however, with improvement in recording and computing, we observe more and more complexity in small-to-moderate earthquakes. We are further investigating the source complexity problem.

A conceptual model of Oklahoma hydraulic structure

Using seismicity analysis, we were able to infer hydraulic diffusivity parameters for Oklahoma from seismicity spatial migrations based on extension of method from Chen & Shearer (2011), and Chen et al., (2012).

This analysis revealed high diffusivity within the Arbuckle Group where fluid can transmit pressure to far distance, and trigger earthquakes. The analysis suggests that the crystalline basement in Oklahoma is no different from plate boundary regions in terms of diffusivity, such as Southern California. The full data analysis can be found in Haffener et al., 2018, JGR.

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