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Moment Tensor Catalog

The Berkeley Seismological Laboratory routinely determines moment tensors for events in northern and central California and notable earthquakes in the western United States. The BSL is operating two automated moment tensor procedures as part of the REDI project. One is based on the time-domain inversion of complete waveform data [Dreger and Romanowicz, 1994], while the second is based on the frequency-domain inversion of surface waves [Romanowicz et al., 1993]. Initially automated in 1994 [Pasyanos et al., 1996], these methods utilize LH data from the BDSN and are now fully incorporated in REDI processing. Analyst reviewed solutions are disseminated via email and are posted to the online catalog. This catalog is available for downloading, but is not currently searchable online.

Moment Tensor Catalog
UC Berkeley Regional Moment Tensor Catalog

UC Berkeley Regional Moment Tensor WWW page.

Catalog Format

Each event in the online catalog contains a minimum of 3 lines. For example,

event       0  mm/dd/yyyy hr:mn:sec latitude longitude dep mag location
            1  st1 err dp1 err rk1 err st2 err dp2 err rk2 err hh  dur  mom ex  mw
           -1 frequency  stations *
            2  st1 err dp1 err rk1 err st2 err dp2 err rk2 err hh  dur  mom ex  mw
           -2 frequency  stations *
idah88196   0  07/14/1988 17:31:33.1  44.456 -114.083   5.0 4.9 Idaho
            1 115      48      -94     301      42     -86      6. -0.5 9.30e22 4.6
           -1 0.02 0.06  ANMO PAS SAO CMB MHC BKS LON 
utah89030   0  01/30/1989 04:06:22.7  38.820 -111.610  24.0 5.0 Utah
            1 205      87        4     115      86     177     18. -0.5 8.40e23 5.2
           -1 0.02 0.06  HRV SCP IPAS SAO MHC CMB BKS COL 
mono90297   0  10/24/1990 06:15:20.7  38.047 -119.157  12.0 5.4 MonoLake
            1 144      80      184      53      86     -10      0   0.0 8.50e23 5.3
           -1 0.02 0.06  ARC BKS CMB MHC SAO STAN
            2 322      83      162      54      72       7      0   0.0 9.00e23 5.3
           -2 0.00 0.00  GSC PAS

The first line describes the event, with an event descriptor, a line id, the origin time, the location (latitude, longitude, depth in km), the magnitude, and the location code. The line id of 0 indicates that it is an event line.

idah88196 0 07/14/1988 17:31:33.1 44.456 -114.083 5.0 4.9 Idaho

Then there will be a series of two-line entries, one for each moment tensor solution. The line id in each indicates the type of the moment tensor solution (1 and -1 indicate the surface-wave frequency-domain solutions, 2 and -2 indicate the complete-waveform time-domain solutions, and 3 and -3 indicate a near-field waveform inversion.

The first of the two moment tensor lines indicates the strike (st1, st2), rake (rk1, rk2), and dip (dp1 , dp2) of the two possible nodal planes, the centroid depth (in km), the source half-duration (in seconds), scalar seismic moment, and Mw;

1 st1 err dp1 err rk1 err st2 err dp2 err rk2 err hh dur mom ex mw 1 115 48 -94 301 42 -86 6. -0.5 9.30e22 4.6

The second of the two moment tensor lines provides information about the stations used in the inversion and the frequncy range:

-1 0.02 0.06 ANMO PAS SAO CMB MHC BKS LON

References
Dreger, D. S., and D. V. Helmberger (1993), Determination of Source Parameters at Regional Distances with Single Station or Sparse Network Data, Journ. Geophys. Res., 98, 8107-8125.

Romanowicz, B., D. Dreger, M. Pasyanos, and R. Uhrhammer (1993). Monitoring of Strain Release in Central and Northern California Using Broadband Data, Geophys. Res. Lett., 20, 1643-1646.

Dreger, D. and B. Romanowicz (1994). Source Characteristics of Events in the San Francisco Bay Region, USGS Open-file report, 94-176, 301-309.

Pasyanos, M.E., D.S. Dreger, and B. Romanowicz (1996), Toward Real-Time Estimation of Regional Moment Tensors, Bull. Seism. Soc. Amer., 86, 1255-1269.