AKA: none
Other ID: L-1-91-NC
Status: Completed
Organization(s):
Funding Program(s): Bay Area Seismic Imaging Experiment (BASIX) (MU017)
Principal Investigator(s): Patrick Hart, Jill McCarthy
Affiliate Investigator(s):
Information Specialist(s):
Data Type(s): Location-Elevation: Navigation, Seismics: Air Gun / Water Gun, Seismics: Boomer, Seismics: Sub Bottom Profiler, Sonar: Single Beam
Scientific Purpose/Goals: Furlong and others (1989) proposed the possibility that the network of faults that bound the San Francisco Bay Area are linked structurally and are all part of an evolving fault system. To test the Furlong and others (1989) model and to obtain fundamental information on the crustal structure and fault geometries that underlie the San Francisco Bay Area, the USGS, in conjunction with the University of California, Stanford University, Pennsylvania State University, and Lawrence Berkeley Laboratory, conducted a major seismic reflection investigation in the fall of 1991 utilizing the marine waterway system that dissects the Bay Area. This study, known as the Bay Area Seismic Imaging Experiment (BASIX) consisted of three complementary seismic reflection and refraction profiling methods: high resolution seismic reflection profiling, wide-angle reflection/refraction profiling, and multichannel seismic profiling. The high-resolution, shallow penetration data were acquired to constrain near-surface faulting, while the wide-angle reflection/ refraction data were acquired to constrain the deep-crustal velocity structure of the crust. (Open-File Report 93-301).
Vehicle(s):
Start Port/Location:
End Port/Location:
Start Date: 1991-09-03
End Date: 1991-09-20
Equipment Used: 12khz, uniboom, airgun, airgunmonitor, GPS, 3.5khz
Information to be Derived: Three complementary seismic reflection and refraction profiling methods: high resolution seismic reflection profiling, wide-angle reflection/refraction profiling, and multichannel seismic profiling. The high-resolution, shallow penetration data were acquired to constrain near-surface faulting, while the wide-angle reflection/refraction data were acquired to constrain the deep-crustal velocity structure of the crust. (Open-File Report 93-301).
Summary of Activity and Data Gathered: A total of 140 km of multichannel reflection data were acquired across the San Francisco Bay Area during 14 nights of profiling. Although each night of profiling was assigned a different line number, several of the lines overlap and they were thus processed together as merged profiles. All totaled, there were four distinct segments to the experiment. The first segment began in the Sacramento River near Rio vista and proceeded west through Honker, Suisun, and San Pablo Bays (lines 101 through 110). The next two segments ran north- south from Richmond to Angel Island (line 113), and from the Bay Bridge to just north of the San mateo Bridge (line 111). The fourth and final segment began in the vicinity of Alcatraz Island and extended west underneath the Golden Gate Bridge, 6 km into the open waters of the Pacific (lines 201-202). 60 to 118 Telseis receivers were moored to the edge of the dredged shipping channel at 100 to 200 m intervals for a fixed spread of 6 to 12 km in length. Each day the receiver array was repositioned, and each night the S.P. Lee steamed along the hydrophone array, with its airgun array firing. The day-to-day small-boat operations began first with the retrieval of the Telseis instruments deployed the previous day. This process utilized a fleet of 4-5 small boats that ranged in size from 6 to 15 m. Once retreived, the instruments were brought back to the S.P. Lee for recharging. The R.V. David Johnston trailed behind these small vessels and recovered the associated buoys and anchors. The Johnston also recorded navigational fixes, which were required in order to check for possible drift of the instrument sites during the night; although anchors were used to maintain instrument position, currents were strong enough in a few areas to move the anchors between deployment and retrieval. Once the instrument retrieval was complete, the Johnston would begin laying out the next line segment. A GPS and Del Norte triangulation system were used to measure the 100- or 200-m distance separating instrument sites. The receiver line was positioned so as to minimize bends in the profile and to keep the buoys out of the active shipping channel. At each site, anchors were deployed and navigation fixes were taken; the anchored sites were marked by orange buoys. The smaller boats followed behind and clipped the recharged Telseis units with cabled hydrophones to these buoys. The hydrophones were weighted so as to minimize movement on the seafloor. The final phase of operation was airgun profiling. Each night the S.P. Lee acquired approximately 24 km of reflection data by looping through the receiver array twice. Along 10 of the 13 multichannel lines the S.P. Lee fired the airgun array while steaming first from east to west and then, reversing course, duplicated the line by steaming from west to east, further doubling the number of airgun shots available for stacking of the seismic signal. In addition to the 13 reflection lines acquired in San Francisco Bay and the Golden Gate region, the airgun array on the S.P. Lee was used primarily as a seismic source for wide-angle profiles recorded along three other lines: the N-S trending line OBS1 in San Francisco Bay; a short transit leg, line TR1 SW of the Golden Gate; and the E-W trending line OBS2 on the continental margin. Lines OBS1 and OBS2 were obtained along two separate deployment of 6 USGS ocean bottom seismometers (OBS) deployed by investigators from the USGS Branch of Atlantic Marine Geology and Woods Hole Oceanographic Institution. The shot interval along line 112/OBS1 was 50 m. The shot interval for lines TR1 and OBS2 was approximately 75 m. Line OBS2 was located coincident to seismic reflection line 13 of Lewis (1990) in order to provide deep structural control on the continental margin west of the San Andreas fault.
Staff: Jonathan Childs, Roberto Anima, Peter Barnes, Armando Buciaga, Tom Chase, Rich Clymer, Diana Collins, Peter Dartnell, Greg Gabel, Erik Gize, Vicky Goetcheus, Michael Hamer, Patrick Hart, Dave Hogg, Kaye Kinoshita, Larry Kooker, Bill Lafleur, Nina Luttinger, Norman Maher, Dennis Mann, Mike Marlow, June Matsueyda, Pat McClellan, Al McClenaghan, Mark McLaughlin, Andy Michael, Walt Olson, Kevin O'Toole, Ben Page, Thomas Parsons, Chris Poppe, Doug Prose, Jean Riordan, Bill Robinson, Stephanie Ross, Holly Ryan, David Scholl, Ray Sliter, Gordon Smith, Joe Svitek, Tracy Vallier, Jim Vaughan, Pat Williams
Affiliate Staff:
George Knudson (Fairfield) - Mechanical Technician
Steve Higgins (Fairfield) - Electronics Technician
Mike Pawlik (Fairfield) - Electronics Technician
Tom McEvilly (University of California
Lawrence Berkeley Laboratories) - Geophysicist
Kevin Furlong (Pennsylvania State University) - Geophysicist
Terry Proffer (Haliburton Geophysicist.) - Geophysicist
Kathy Furlong (Pennsylvania State University) - Unspecified Investigator
Kate King (CNN) - Unspecified Investigator
Rick Blackbird (CNN) - Unspecified Investigator
Chris Vincent (CNN) - Unspecified Investigator
Roy Kiesling (Chase Boat
USGS Western Region) - Vol. Unspecified Investigator
David Verdonck (Pennsylvania State University
LLL) - Geophysicist
Eleni Karageorgi (Lawrence Berkeley Laboratories) - Unspecified Investigator
Joel Rosenbaum (Vacaville Reporter) - Photographer
Robert Reed (Vacaville Reporter) - Unspecified Investigator
George Thompson (Stanford University) - Geophysicist
David McMahon (BC&DC) - Unspecified Investigator
Notes:
Staff information imported from InfoBank
Al McClenaghan - Ship Captain
Chris Poppe (USGS Western Region) - Chief Mate
Bill Lafleur (USGS Western Region) - Chief Engineer
Jill McCarthy (USGS Western Region) - Chief Scientist
Kevin O'Toole (USGS Western Region) - Mechanical Technician
Walt Olson (USGS Western Region) - Mechanical Technician
Larry Kooker (USGS Western Region) - Electronics Technician
Bill Robinson (USGS Western Region) - Electronics Technician
Jim Vaughan (USGS Western Region) - Electrical Engineer
Dave Hogg (USGS Western Region) - Electronics Technician
Kaye Kinoshita (USGS Western Region) - Navigator
George Knudson (Fairfield) - Mechanical Technician
Steve Higgins (Fairfield) - Electronics Technician
Mike Pawlik (Fairfield) - Electronics Technician
Tom McEvilly (University of California, Lawrence Berkeley Laboratories) - Geophysicist
Pat Hart (USGS Western Region) - Geophysicist
Jon Childs (USGS Western Region) - Geophysicist
Kevin Furlong (Pennsylvania State University) - Geophysicist
Terry Proffer (Haliburton Geophysicist.) - Geophysicist
Pat McClellan (City Of San Leandro) - Geophysicist
Mike Marlow (USGS Western Region) - Watchstander
Kathy Furlong (Pennsylvania State University) - Unspecified Investigator
Kate King (CNN) - Unspecified Investigator
Rick Blackbird (CNN) - Unspecified Investigator
Chris Vincent (CNN) - Unspecified Investigator
Gordon Smith (David Johnston) - Ship Captain
Mark McLaughlin (David Johnston) - Unspecified Investigator
Tom Parsons (Stanford University, David Johnston) - Unspecified Investigator
Michael Hamer (David Johnston, USGS Western Region) - Navigator
Roberto Anima (Fast Eddy, USGS Western Region) - Ship Captain
Shawn Dadisman (Fast Eddy, USGS Western Region) - Unspecified Investigator
Armando Buciaga (Fast Eddy, USGS Western Region) - Unspecified Investigator
Tom Chase (Chase Boat, USGS Western Region) - Ship Captain
Pete Dartnell (Chase Boat, USGS Western Region) - Unspecified Investigator
Roy Kiesling (Chase Boat, USGS Western Region) - Vol. Unspecified Investigator
Greg Gabel (Caltrans) - Ship Captain
Holly Ryan (Caltrans) - Unspecified Investigator
David Verdonck (Pennsylvania State University, LLL) - Geophysicist
Dennis Mann (Revenge, USGS Western Region) - Ship Captain
Ray Sliter (Revenge, USGS Western Region) - Unspecified Investigator
Joe Svitek (Revenge, USGS Western Region) - Unspecified Investigator
Rich Clymer (Mako, USGS Western Region) - Unspecified Investigator
Pat Williams (Mako, USGS Western Region) - Unspecified Investigator
Peter Barnes (R/V Estero, USGS Western Region) - Ship Captain
Erik Gize (R/V Estero, USGS Western Region) - Unspecified Investigator
Jean Riordan (USGS Western Region) - Unspecified Investigator
Norman Maher (USGS Western Region) - Unspecified Investigator
Vicky Goetcheus (USGS Western Region) - Unspecified Investigator
Dave Scholl (USGS Western Region) - Geophysicist
Eleni Karageorgi (Lawrence Berkeley Laboratories) - Unspecified Investigator
Joel Rosenbaum (Vacaville Reporter) - Photographer
Robert Reed (Vacaville Reporter) - Unspecified Investigator
George Thompson (Stanford University) - Geophysicist
Ben Page (USGS Western Region) - Geophysicist
David McMahon (BC&DC) - Unspecified Investigator
Doug Prose (USGS Western Region) - Photographer
Nina Luttinger (USGS Western Region) - Photographer
Tracy Vallier (USGS Western Region) - Geologist
Andy Michael (USGS Western Region) - Geophysicist
Stephanie Ross (USGS Western Region) - Navigator
Diana Collins (USGS Western Region) - Unspecified Investigator
June Matsueyda (USGS Western Region) - Unspecified Investigator
Location:
San Francisco Bay
| Boundaries | |||
|---|---|---|---|
| North: 38.11173 | South: 37.20842 | West: -123.52 | East: -121.70993 |
Platform(s):
.jpg) Samuel Phillips Lee |
Anima, R.J., Williams, P.L., and McCarthy, J., 1992, High-resolution marine seismic reflection profiles across East Bay faults, in Galehouse, Jon S., ed., Programs and abstracts of the Second conference on Earthquake hazards in the eastern San Francisco Bay area: California Division of Mines and Geology Special Publication 113, 4 p.
Brocher, T.M., and Moses, M.J., 1993, Onshore-offshore wide-angle seismic recordings of the San Francisco Bay Area Seismic Imaging Experiment (BASIX): the five-day recorder data: U.S. Geological Survey Open-File Report 93-276, 89 p., https://doi.org/10.3133/ofr93276.
Brocher, T.M., McCarthy, Jill, and Holbrook, W. Steven,, 1996, Imaging the transform plate boundary in the San Francisco Bay area, California: , Geological Society of America Abstracts with Programs. , pp. 216–216.
Brocher, T.M., McCarthy, J., Hart, P.E., Holbrook, W.S., Furlong, K.P., McEvilly, T.V., Hole, J.A., and Klemperer, S.L., 1994, Seismic evidence for a lower-crustal detachment beneath San Francisco Bay, California: Science, v. 265 no. 5177, pp. 1436–1439.
Childs, J.R., Hart, P.E., McCarthy, J., and Marlow, M.S, 1994, High-resolution seismic-reflection studies of submerged fault zones throughout the San Francisco Bay area: American Geophysical Union Eos, Transactions, v. 75 no. 44, pp. 684–684.
Hart, P., McCarthy, J., Karageorgi, E., and McEvilly, T., 1993, Seismic reflection profiling in the San Francisco Bay area; the 1991 Bay Area Seismic Imaging Experiment (BASIX): , Geological Society of America Abstracts with Programs. , pp. 417–418.
Hart, P.E., Clymer, R.W., and Karageorgi, E.D., 1992, Geometry of the San Francisco Bay area faults; preliminary results from BASIX, in Galehouse, Jon S., ed., Programs and abstracts of the Second conference on Earthquake hazards in the eastern San Francisco Bay area: California Division of Mines and Geology Special Publication 113, pp. 30–30.
Holbrook, W.S., Brocher, T.M., McCarthy, Jill, Hole, J.A., and ten Brink, U.S., 1994, Crustal structure beneath the San Francisco Bay Block and Central California continental margin: American Geophysical Union Eos, Transactions, v. 75 no. 44, pp. 664–664.
McCarthy, J., Hart, P.E., and Oppenheimer, D., 1995, High angle faulting in western Sacramento Delta region, Pittsburg, California: American Association of Petroleum Geologists Bulletin, v. 79 no. 4, pp. 592–592.
McCarthy, J., and Hart, P.E., 1993, Data report for the 1991 Bay area seismic imaging experiment (BASIX): U.S. Geological Survey Open-File Report 93-301, 26 p., https://doi.org/10.3133/ofr93301.
McCarthy, J., Hart, P., Karageorgi, E., and McEvilly, T., 1993, Seismic profiling across an evolving transform margin; results from the 1991 Bay Area Seismic Imaging eXperiment (BASIX): , Geological Society of America Abstracts with Programs. , pp. 310–310.
McCarthy, J., Hart, P.E., Anima, R., Oppenheimer, D., and Parsons, T., 1994, Seismic evidence for faulting in the western Sacramento Delta region, Pittsburg, California: American Geophysical Union Eos, Transactions, v. 75 no. 44, pp. 684–685.
McEvilly, T.V., and McCarthy, J., 1992, BASIX; the Bay Area Seismic Imaging Experiment report, in Galehouse, Jon S., ed., Programs and abstracts of the Second conference on Earthquake hazards in the eastern San Francisco Bay area: California Division of Mines and Geology Special Publication 113, pp. 47–47.
Parsons, T., McCarthy, Jill, and Hart, P.E., 1994, The nature of lower crustal reflectors beneath San Francisco Bay, California: American Geophysical Union Eos, Transactions, v. 75 no. 44, pp. 643–643.
Pope, D.C., Brocher, T.M., McCarthy, J., Karageorgi, E.D., and Holbrook, W.S., 1993, Comparison of recording technology for onshore-offshore seismic profiling of continental margins; examples from BASIX: , American Geophysical Union Fall Meeting Abstracts. pp. 445–445.
Williams, P.L., McEvilly, T.V., Anima, R., McCarthy, J., Nakata, T., Okamura, M., and Shimazaki, K., 1993, Fault activity, geometry, and recurrence behavior at the junction of the Rodgers Creek and Pinole faults, California: American Geophysical Union Eos, Transactions, v. 74 no. 43, pp. 411–411.
| Survey Equipment | Survey Info | Data Type(s) | Data Collected |
|---|---|---|---|
| 12khz | --- | Single Beam | Survey information |
| uniboom | --- | Boomer | uniboom (data on FAD) |
| airgun | --- | Air Gun / Water Gun | Edited seismic shot point data l-1-91-nc.420_065 (Provisional best file) Edited seismic shot point data l-1-91-nc.420_065-_nad27 Edited seismic shot point data l-1-91-nc.420 |
| airgunmonitor | --- | Air Gun / Water Gun | seismic paper rolls (data in holdings) |
| GPS | --- | Navigation | Global positioning system (GPS) data l-1-91-nc.065 (Provisional best file) Best file with nav in ArcInfo E00 format Global positioning system (GPS) data l-1-91-nc.065_degree |
| 3.5khz | --- | Sub Bottom Profiler | Survey information |
