Reprocessed boomer 3D seismic-reflection data collected in Estero Bay, offshore of Morro Bay, central California, from 2012-08-12 to 2012-10-05 (USGS field activity P-04-11-CC)

Seismic data were acquired using a triple-plate boomer source operated at 1.75 kJ and the P-Cable streamer system. The 3D data show a frequency range of approximately 100-700 Hz, with a dominant frequency of 200-225 Hz (PG&E, 2014). The P-Cable system consisted of 14, 8-channel digital streamers with 6.25 m hydrophone group spacing (Nishenko and others, 2012; Ebuna and others, 2013). Data were sampled at 0.25 ms with a record length of 0.75 s two-way travel-time. Seismic processing steps conducted by Fugro Consultants included quality control, tidal corrections, velocity analysis, NMO correction, stacking, surface related multiple elimination, deconvolution, crossline statics, and pre-stack migration (Fugro Consultants Inc., 2012; PG&E, 2014). However, upon public release and inspection by the USGS, significant high-frequency noise was observed, limiting the interpretation of imaged fault structures (Kluesner and Brothers, 2016).

The publically released 3D seismic data were downloaded and analyzed by the USGS, and a post-stack data-conditioning workflow was designed to reduce noise and enhance the overall quality. The data conditioning workflow used on this dataset followed that of Kluesner and Brothers, 2016. Initially, data were imported into the OpendTect software package and a dip-steering volume was calculated using a 1x1x1 (inline, crossline, sample interval) calculation window. Following dip-steering calculation a median filter was applied with a 1x1x1 stepout, resulting in a smoothed 3D volume of dip and azimuth information for all seismic events. The dip-steered median filter was then applied to the data between 0 and 0.5 s TWTT, with a 1x1 (inline, crossline) stepout. Filtered results were then subtracted from the original data to produce a volume with significant noise suppression. Both random and apparent acquisition noise were suppressed, while enhancing laterally continuous events. Following generation of the cleaned data volume the results were exported as a new 3D SEG-Y file using the OpendTect software package.

Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.

Data were moved to a new repository, and metadata was edited to reflect the new location. Other edits were performed as needed to bring the metadata up to PCMSC standards, including a slight rewording of the title. No data were changed.