| Identifier | L191NC | ||||||||
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| Alternate names | L-1-91-NC | ||||||||
| Purpose | 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). | ||||||||
| Description | Chief Scientists: Pat Hart, Jill McCarthy. Geophysical data (3dot5khz, 12khz, uniboom, airgun, airgunmonitor) of field activity L-1-91-NC in San Francisco Bay from 09/03/1991 to 09/20/1991 | ||||||||
| Location | San Francisco Bay | ||||||||
| Summary | 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. | ||||||||
| Info 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). | ||||||||
| Comments | 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 | ||||||||
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| Activity | Geophysical |
| Principal investigators | Patrick E HartMcCarthy, Jill | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| 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 |
| Data category: | Location-Elevation, Seismics, Sonar |
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| Data type: | Navigation, Air Gun / Water Gun, Boomer, Sub Bottom Profiler, Single Beam |
| Dataset name | Equipment | Description | Dataset contact |
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| Survey information | 12khz | Jill McCarthy | |
| uniboom | uniboom | data on FAD | Patrick E Hart |
| Edited seismic shot point data l-1-91-nc.420 | airgun | Jill McCarthy | |
| Edited seismic shot point data l-1-91-nc.420_065 | airgun | Provisional best file | Jill McCarthy |
| Edited seismic shot point data l-1-91-nc.420_065-_nad27 | airgun | Jill McCarthy | |
| seismic paper rolls | airgunmonitor | data in holdings | Carol A Reiss |
| Best file with nav in ArcInfo E00 format | GPS | Jill McCarthy | |
| Global positioning system (GPS) data l-1-91-nc.065 | GPS | Provisional best file | Jill McCarthy |
| Global positioning system (GPS) data l-1-91-nc.065_degree | GPS | Jill McCarthy | |
| Survey information | 3.5khz | Jill McCarthy |
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