NCSN and SHFN waveform data are sent to the NCEDC via the Internet and/or private IP network. The NCSN event waveform files are automatically transferred from the USGS Menlo Park to the NCEDC as part of the routine analysis procedure by the USGS, and are automatically verified and archived by the NCEDC.
The NCEDC maintains a list of teleseismic events recorded by the NCSN, which is updated automatically whenever a new NCSN event file is received at the NCEDC, since these events do not appear in the NCSN catalog.
The NCSN operates a total of 15 continuously telemetered digital broadband stations: 11 stations in northwest California and southwest Oregon in support of the USGS/NOAA Consolidated Reporting of EarthquakeS and Tsunamis (CREST) system, two digital broadband stations in the Mammoth region, and two digital broadband stations in the Parkfield region. The NCEDC established procedures to create an archive of continuous data from these stations, in addition to the event waveform files. These data are currently sampled at 100 Hz and are archived continuously. At the USGS's request, the 3 component 500 Hz data from the Mammoth Deep Hole are also continuously archived.
In January 2005, in response to interest in non-volcanic tremors detected in northern and central California, we started to archive continuous high frequency data from 21 additional NCSN stations in selected regions of northern California and Parkfield. In response to requests for additional continuous NCSN data, we received approval to rebudget funds to purchase disk and tape systems to support the reading and archiving of continuous waveforms from the entire NCSN from 2001 to the present, and to establish procedures for continuous archiving of current NCSN data. We are purchasing the require hardware, and will start reading the NCSN data tapes within the next month. We are working with the NCSN to provide reliable delivery of all current NCSN data channels to the NCEDC over the Internet for continuous archiving.
Berkeley Seismological Laboratory
215 McCone Hall, UC Berkeley, Berkeley, CA 94720-4760
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