Earthquake extraction and correlation energy at Long Beach, California seismic survey

Earthquake extraction and correlation energy at Long Beach, California seismic survey

Jason P. Chang and Sjoerd de Ridder

Abstract:

Seismic interferometry of passive data offers a potential solution to creating reservoir-scale images in urban environments. A four-month, high station density passive seismic dataset collected in Long Beach, California is ideal for testing this hypothesis. Preliminary work on these data is promising. We clearly capture waveforms from earthquakes near (less than $15$  km) and far (greater than $250$  km). We successfully construct virtual sources through cross-correlation of low-frequency energy ($0.175$ to $1.75$  Hz). The correlated energy is quite noisy and appears to be directed toward the northeast, suggesting that longer correlation times are needed for land data and that the Pacific Ocean is likely producing strong directed energy, respectively. Furthermore, the quality of correlation results differ depending on the time window. We argue that these differences are attributed to weather conditions, with records during stormier periods producing cleaner Green's functions than records during calmer periods.

Earthquake extraction and correlation energy at Long Beach, California seismic survey