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Southern California Caltalogs
Known Issues with the Catalog

The Caltech Seismology Lab, USGS, and the SCEDC have been working toward compiling and converting all available historic seismic data holdings to create a single-source for online access to southern California earthquake data. Older parametric data have been loaded into the SCEDC Oracle 10g database and most digital waveform data has been converted into the modern archival format, miniSEED, and are available for download. Most earthquakes have been analyzed or re-analyzed if necessary, relocated and assigned updated magnitudes, based on the Kanamori attenuation function. Quality review has also been conducted. Currently only 1980 is still unavailable.

It is likely that, in the not-too-distant future, we will recompute all magnitudes using the statewide CISN ML corrections and attenuation function. In the meantime, however, most of the earthquake catalog can be considered finalized as we can make it without a great amount of effort.

Although this work is ongoing, we have made the data available to users of the catalog with the known issues with the catalog presented below (in chronological order). Users who find any errors should report them to SCEDC or the SCSN.

Years
Online
Waveforms
Stations

Pick
Source

Location
Source
Magnitude
Source
Problems
1932-1971
Y
Original drum records and microfilm
  • 7 (or fewer at times) in 1932
  • 40 by 1971, with increases mainly in response to Kern County 1952 and San Fernando 1971.
    		•
    Phase cards from the era, made from photographic and heliocorderdrums (reading error 0.1+ sec)
  • Hypoinverse
  • CUSP location code "Grope"
  • Hadley-Kanamori 1D velocity model
  • Rarely "simulps" (because it uses S-P times).
  • Wood-Anderson amplitudes (Ml)
  • Short period vertical drums (Mh)
    		•
  • No digital waveforms.
  • Low quality locations, esp. in early years.
  • Some locations based on only 2 stations. Remark included.
  • Some locations assumed (e.g. in aftershock sequences). Remark included.
  • Most events do not have stations close enough to determine depth. Depth was usually set to 6m.
  • Magnitude of completeness varies w/time and location.
    • 1972-1976
    Y
    Original drum records and microfilm
  • 40 stations in 1972
  • 144 in 1976
    		•
  • Phase cards, made from photographic and heliocorder drums (reading error 0.1+ sec).
  • Develocorders (reading error 0.05 sec).
    		•
  • Hypoinverse
  • CUSP location code "Grope"
  • Hadley-Kanamori 1D velocity model
    		•
  • Wood-Anderson amplitudes (Ml)
  • Short-period vertical drums (Mh)
  • Duration on develocorder (Md)
  • No digital waveforms.
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
  • Smallest events all seem to have magnitude 1.7
  • Magnitude of completeness varies with location.
    • 1977-1979
    Y
    Digital EHZ and a few EHE,N channels
    144 to 157
  • Interactive picks on CEDAR digital waveforms (reading error 0.02 sec)
  • Develocorders (reading error 0.05 sec)
  • Phase cards, made from photographic and heliocorder drums (reading error 0.1 sec).
    		•
  • Hypoinverse
  • CUSP location code "Grope"
  • Hadley-Kanamori 1D velocity model
    		•
  • Wood-Anderson amplitudes (Ml)
  • Short-period vertical drums (Mh)
  • Duration on develocorder (Md)
  • No digital waveforms.
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
  • Smallest events all seem to have magnitude 1.7
  • Magnitude of completeness varies with location.
    • 1980
    N
    Digital EHZ and a few EHE,N channels
    157 to 162
  • Interactive picks on CEDAR/CUSP digital waveforms (reading error 0.02 sec).
  • Develocorders (reading error 0.05 sec).
  • Phase cards, made from photographic and heliocorder drums (reading error 0.1+ sec)
    		•
  • Hypoinverse
  • Hadley-Kanamori 1D velocity model
    		•
  • Wood-Anderson amplitudes (Ml)
  • Short-period vertical drums (Mh)
  • Digital coda analysis (Mc or Mca)
  • Interactive duration (Mh)
  • Has not been analyzed thoroughly. Amplitudes have not been inserted, etc.
  • Some events have no digital waveforms (due to either failure to trigger RT system, or degraded archive tapes).
  • For a few events with no extant digital waveforms, picks were read from hardcopies. A remark is included.
  • A few small events with no waveforms and no amplitudes have no magnitude.
  • During this time period, some channel assignments are not correct. We ignored the affected channels.
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
    • 1981-1991
    Y
  • Digital EHZ and a few EHE,N channels
  • Some EL channels
  • First broadband stations (HH and BH channels) introduced.
    		•
    162 to 228
  • Interactive picks on CUSP digital waveforms (reading error 0.01 sec)
  • Rarely, phase cards, made from photographic and heliocorder drums (reading error 0.1 sec).
    		•
  • Hypoinverse
  • Hadley-Kanamori 1D velocity model
    		•
  • Wood-Anderson amplitudes (Ml)
  • Synthetic Wood-Anderson amplitudes from EL channels (Ml)
  • Short-period vertical drums (Mh)
  • Digital coda analysis (Mc or Mca)
  • Interactive duration (Mh)
  • Few events have no digital waveforms (due to either failure to trigger RT system, or degraded archive tapes.
  • A few small events with no waveforms and no amplitudes have no magnitude.
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
  • There may still be a few bogus M3 or M4 events, especially during major sequences (please report these if you find them!)
  • During this time period, some channel assignments are not correct. We ignored the affected channels.
  • For a few events with no extant digital waveforms, picks were read from hardcopies. A remark is included.
    • 1992-2000
    Y
  • Digital EHZ and a few EHE,N channels
  • Some EL channels
  • Increasing number of HH and BH channels through the time period.
    • 228 to 328
    Interactive picks on CUSP digital waveforms (reading error 0.01 sec).
  • Hypoinverse
  • Hadley-Kanamori 1D velocity model
    		•
  • Synthetic Wood-Anderson amplitudes from HH and BH channels.(Ml)
  • Less frequently, synthetic Wood-Anderson amplitudes from EL channels. (Ml)
  • Digital coda analysis (Mc or Mca)
  • Interactive duration (Mh)
  • Some events have no digital waveforms (due to either failure to trigger RT system, or degraded archive tapes).
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
  • A few small events with no waveforms and no amplitudes have no magnitude.
  • Some mis-identified quarry blasts have been reported.
    There may still be a few bogus M3 or M4 events, especially during major sequences (please report these if you find them!)
    		•
    2001-present
    Y
  • HH and BH channels.
  • Digital EHZ and a few EHE,N channels
    		•
    303 to 375+
    Interactive picks on TriNet digital waveforms (reading error 0.01 sec).
  • Hypoinverse
  • Hadley-Kanamori 1D velocity model
    		•
  • Synthetic Wood-Anderson amplitudes from HH and BH channels.(Ml)
  • Interactive duration (Mh)
  • A few small events with no waveforms and no amplitudes have no magnitude.
  • Velocity model does not work well in basin regions. Depth often fixed at 6km or 15 km (when model tries to put earthquake deeper than 15km)
  • Some mis-identified quarry blasts have been reported.