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National Information Service for Earthquake Engineering
University of California, Berkeley |
Wide-Angle Sesimic Reflection/Refraction Recordings of Marine Airgun Profiling.
Thomas M. Brocher, & Michael J. Moses, USGS, Menlo Park, California.
Wide-angle seismic reflection/refraction data obtained in the vicinity of the epicenter of the 1989 Loma Prieta earthquake provide evidence for a slab of oceanic crust extending from the deep sea floor to the San Andreas fault. During marine seismic relection profiling of the north-central California margin in May 1990, two onshore recording arrays were deployed transverse to and straddling the San Andreas fault at the latitude of Loma Prieta. The Loma Prieta array consisted of 13 stations stretching from the coast landward 94 km to the San Joaquin valley. A shorter array, located 25 km from Ano Nuevo to Cedar Mountain in the Diablo Range. These arrays recorded two 61-km-long, colinear, off-end, reflection lines from source-receiver offsets as small as 11 km to offsets as large as 165 km.
Data consist of common-receiver gathers, one gather per 9-track tape, written in SEG-Y format. Gathers are identified by a reflection line number and a station number. Gathers from Loma Prieta (LP) array contain about 3660 graces, three traces for each airgun shot (one for each of three orthogonal seismometers). Gathers from Ano Nuevo (AN) array contain about 3510 traces. Gathers are stored in reduced format: times have been transformed according to Tred=T-X/6, where T is the original travel time and X is the source-receiver offset. The gathers have been high-pass filtered above 3 Hz to remove low-frequency noise. Each trace is about 23 seconds long; or roughly 2301 2-byte samples and a 240 byte header for each trace.
File list:
LP3210 LP3220 LP3230 LP3240 LP3250
LP3260 LP3270 LP3280 LP3290 LP32100
LP32110 LP32120
LP3810 LP3820 LP3830 LP3840 LP3850
LP3860 LP3870 LP3880 LP3890 LP38100
LP38110 LP38120 LP38130
AN3210 AN3220 AN3230 AN3240 AN3250
AN3260
AN3810 AN3820 AN3830 AN3840 AN3850
AN3860