NCEDC News/Blog
Timing problem at Mammoth analog stations 01/22/2015 - 01/27/2015
Categories: Timing Errors | Northern California Earthquake Data Center (NCEDC) | Mammoth | Earthquake Catalogue | Catalogs
January 30, 2015
The Northern California Earthquake Data Center (NCEDC) archives seismic waveform data from the Northern California Seismic Network (network code NC). This announcement refers to network NC seismic waveform data (both continuously archived data and event gathers) for dates, stations, and channels listed below. Earthquake catalog locations were not affected (see below).
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The NCSN experienced problems with the TrueTime clock responsible for providing the IRIGE time at Mammoth from 01/22/2015 23:35:11 through 01/27/2015 23:59:12. During this interval, timing is uncertain for all the analog stations digitized at Mammoth. However, events recorded during this period were timed and located with stations not affected by the problem, and the origin times of the cataloged events are accurate, with fairly good locations.
Beginning of problem - time tears from lost/regained time lock, presumably due to TrueTime IRIGE changes:
20150121_UTC_23:35:11 overlap -0.99 s
20150122_UTC_01:02:58 gap 1.01 s
20150122_UTC_06:02:31 overlap -0.99 s
20150122_UTC_06:40:09 gap 1.01 s
20150122_UTC_07:30:11 overlap -0.99 s
End of problem - TrueTime swap done, adsend synced:
20150127_UTC_23:59:12 Time-code status: Locked-on
Timing between 01:02:58-06:02:31 and 06:40:09-07:30:11 on 1/22 is probably ok.
This timing problem affects the following channels:
IRGMM ATT NC --
MCD EHZ NC --
MCS EHZ NC --
MCV EHZ NC --
MDC EHZ NC 02
MDR EHZ NC 02
MDR ELE NC --
MDR ELN NC --
MEM EHZ NC --
MEM ELE NC --
MEM ELN NC --
MFB EHZ NC --
MGPB EHZ NC --
MLC EHZ NC --
MLH EHZ NC --
MLM EHZ NC --
MMP EHZ NC --
MMS EHZ NC --
MRC EHZ NC --
MRD EHZ NC 02
MTU EHZ NC 02
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