Files

Dataset zip file

Download (11.0 GB)

Navigation File

Download (6.7 MB)

Seismic Metadata v.1

FGDC metadata (xml)

Download (13.7 KB)

FGDC metadata (text)

Download (13.4 KB)

Contact the NAMSS Team if you have trouble downloading the dataset.

General Information

Data Type

Singlechannel Seismic

Data Acquisition System

Chirp

Contributor

Pacific Coastal and Marine Science Center

Dates

Started on June 8, 2011, and ended on June 22, 2011.

Number of Tracklines

29

Distance Shot

296 km

Description

Chirp seismic-reflection data of field activity S-07-11-SC: offshore San Diego, and Los Angeles Counties, southern California from 2011-06-08 to 2011-06-22

Purpose

This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2011 to collect information on active offshore faults. The survey area is offshore southern California between Long Beach and San Diego. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using an EdgeTech 512 subbottom profiler. Subbottom acoustic penetration spanned tens to about 50 meters, variable by location.

Notes

Citation: Sliter, R.W., Conrad, J.E., Ryan, H.F., and Triezenberg, P.J., 2017, Chirp seismic-reflection data of field activity S-07-11-SC: offshore San Diego, and Los Angeles Counties, southern California from 2011-06-08 to 2011-06-22: U.S. Geological Survey data release, doi:10.5066/F7X63K3K

Geographic Features

Southern California

Dataset Information

Processed Methods

Seismic Reflection

Processed Data Classes

Other

Data File Formats

SEG-Y

Embedded Navigation

Yes

Data Class

Processed

Seismic Data Provenances

Digitally Acquired Digital SEG

Data Media

Online

Processing

Seismic-reflection data were collected using an Edgetech 512 Chirp subbottom profiling system consisting 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 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 envelope” 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

Datum

World Geodetic System 1984 (WGS84)

Location

Tracklines 29 total

Name Length (km) First SP Last SP First CDP Last CDP
OSC-104 21 1 6,775 1 6,775
OSC-105 16 1 4,653 1 4,653
OSC-106 10 1 3,314 1 3,314
OSC-107 12 1 3,434 1 3,434
OSC-108 13 1 4,017 1 4,017
OSC-109 21 1 6,012 1 6,012
OSC-110 30 1 3,992 1 3,992
OSC-111 3 1 977 1 977
OSC-111A 8 1 2,413 1 2,413
OSC-112 5 1 1,461 1 1,461
OSC-112A 15 1 4,718 1 4,718
OSC-113 21 1 5,941 1 5,941
OSC-114 7 1 1,928 1 1,928
OSC-115 8 1 2,230 1 2,230
OSC-116 6 1 1,694 1 1,694
OSC-117B 1 1 271 1 271
OSC-118 4 1 1,370 1 1,370
OSC-118A 3 1 1,038 1 1,038
OSC-119 4 1 1,250 1 1,250
OSC-119A 6 1 2,222 1 2,222
OSC-120 9 1 3,300 1 3,300
OSC-121 11 1 3,555 1 3,555
OSC-122 9 1 3,520 1 3,520
OSC-123 10 1 3,184 1 3,184
OSC-132 11 1 4,786 1 4,786
OSC-132A 10 1 4,231 1 4,231
OSC-133 4 1 1,804 1 1,804
OSC-149 10 1 5,150 1 5,150
OSC-149A 10 1 3,502 1 3,502