Skip to main content
U.S. flag

An official website of the United States government

Cruise summary for P-1-02-SC: acoustic imaging of natural oil and gas seeps and measurement of dissolved methane concentration in coastal waters near Pt. Conception, California

June 1, 2003

Water-column acoustic anomalies and methane concentrations were documented in coastal waters surrounding Pt. Conception, California, in March 2002. The purpose of this survey, supported by the Minerals Management Service, was to locate active oil and gas seeps in the area as a background for further studies to determine hydrocarbon flux, mainly oil, into the environment.


Objectives in reaching this goal are to (1) document the locations and geochemically fingerprint natural seeps within the offshore southern Santa Maria Basin; (2) geochemically fingerprint coastal tar residues and potential sources, both onshore and offshore, in this region; (3) establish chemical correlations between offshore active seeps and coastal residues thus linking seep sources to oil residues; (4) measure the rate of natural seepage of individual seeps and attempt to assess regional natural oil and gas seepage rates; (5) attempt to predict transport pathways of oil from seep sources to the coastline and; (6) interpret the petroleum system history for the natural seeps.


This survey, addressing objective 1, focused on the area from offshore Surf Beach to the north and Gaviota to the south in water depths ranging from 20 to 500m. In addition, nine stations were sampled outside this area to provide a regional context. Water-column methane concentrations were measured in water samples collected from the R/V Point Sur with Niskin bottles from various depths. A total of 724 water samples from 94 stations were collected.

Publication Year 2003
Title Cruise summary for P-1-02-SC: acoustic imaging of natural oil and gas seeps and measurement of dissolved methane concentration in coastal waters near Pt. Conception, California
DOI 10.3133/ofr03122
Authors T.D. Lorenson, Jennifer A. Dougherty, William Ussler, Charles K. Paull
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2003-122
Index ID ofr03122
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center
Was this page helpful?