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General Information

Data Type

Singlechannel Seismic

Data Acquisition System



Pacific Coastal and Marine Science Center


Started on July 6, 2009, and ended on July 10, 2009.

Number of Tracklines


Distance Shot

51 km


Chirp seismic-reflection data of field activity S-5-09-SC: San Pedro Basin, offshore southern California from 2009-07-06 to 2009-07-10


This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2009 to explore a possible connection between the San Diego Trough Fault and the San Pedro Basin Fault. The survey is in the San Pedro Basin between Santa Catalina Island and San Pedro, California. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using an EdgeTech 512 chirp subbottom profiler. Subbottom acoustic penetration spanned tens to about 50 meters, variable by location.


Citation: Sliter, R.W., Conrad, J.E., Ryan, H.F., and Triezenberg, P.J., 2017, Chirp seismic-reflection data of field activity S-5-09-SC: San Pedro Basin, offshore southern California from 2009-07-06 to 2009-07-10: U.S. Geological Survey data release, doi:10.5066/F75Q4T8F

Geographic Features

Southern California

Dataset Information

Processed Methods

Seismic Reflection

Processed Data Classes


Data File Formats

SEG-Y, Text

Embedded Navigation


Data Class


Seismic Data Provenances

Digitally Acquired Digital SEG

Data Media



Seismic-reflection data were collected using an Edgetech 512 Chirp subbottom profiling system consists of a source transducer and an array of receiving hydrophones housed in a 500-lb “fish” towed at a depth of several meters below the sea surface. The swept-frequency “chirp” source signal is approximately between 500 and 4,500 Hz, and data are recorded by hydrophones located on the bottom of the fish. At boat speeds of 4 to 4.5 nm/hour, seismic traces were collected roughly every 1 to 2 meters. The data consist of three-channels: a raw channel, a 90-degree phase-shifted channel and an “amplitude envelop” channel created and transformed internally from the other two channels. The data were recorded in standard SEG-Y 16-bit integer format with Triton Subbottom Logger (SBL) software that merges seismic-reflection data with differential GPS navigation data.

The processed seismic-reflection SEG-Y files consist of the internally transformed amplitude envelope channel corrected for the depth of the fish below the sea surface using Paradigm Geophysical Echos seismic processing software:
1) SEG-Y channel with sequence number “1” was written to a SEG-Y file;
2) The fish depth header word was read and converted from millimeters to two-way travel time to create a fish-depth static value; and
3) The fish depth static was applied to the data to correct for the vertical up and down movement of the Chirp fish and a final processed SEG-Y was output.

Navigation Information


World Geodetic System 1984 (WGS84)


Tracklines 8 total

Name Length (km) First SP Last SP First CDP Last CDP
SPC-03 10 1 2,629 -- --
SPC-04 11 1 3,376 -- --
SPC-05 8 1 2,058 -- --
SPC-06 6 1 1,670 -- --
SPC-07 6 1 1,560 -- --
SPC-08 2 1 441 -- --
SPC-08A 1 1 150 -- --
SPC-08B 9 1 2,649 -- --