MOBB - the first cabled broadband observatory for northern CA

February 27th, 2009

February 27th, 2009

The NCEDC is pleased to announce the real-time data from MOBB, the first cabled ocean bottom broadband seismic observatory off the coast of California.

The MOBB site is a joint project of the UC Berkeley Seismological Laboratory (BSL) and the Monterey Bay Aquarium Research Institute (MBARI), located at 1000 meters depth off the coast of Monterey bay in northern California. It acquires and transmits real-time data from a Guralp broadband seismometer, a SIO/UCSD differential pressure gauge, and a Falmouth Scientific current meter over a 3.5 km extension cable that connects to the Monterey Accelerated Research System (MARS) 52-km undersea cable off the coast of Monterey Bay in northern California. Data are directly transmitted to data collection nodes at MBARI and BSL, where they will be incorporated into the real-time monitoring system of the Northern California Seismic System (NCSS), a component of the California Integrated Seismic System.

The MOBB real-time data are archived by the NCEDC and available via all of the standard NCEDC data request methods.

More information about the MOBB/MARS system can be found at:

The MARS cable system is testbed for cabled ocean observatories, and is therefore a "work-in-progress". Certain items, such as the pulse-per-second signal used for precise timing, are still under development. Therefore, the accuracy of the timing of data from MOBB may vary over time.

The NCEDC is a joint project of the University of California, Berkeley and the USGS, with facilities located at the University of California, Berkeley. Please send us email at ncedcinfo@ncedc.org or fill out our comments form if you have questions or comments about these changes.

Changes to the NCSN/NCEDC catalog

July 18th, 2008

July 18th, 2008

The NCEDC has migrated all NCSN phase, catalog, and waveform information from ASCII files into the CISN database. This migration necessitated the following changes.

  • Formerly the catalog referenced historic events without waveforms for the period 1966/07 - 1998/12 using negative event ID numbers. During the migration of the catalog into the CISN database, all 228,690 negative event ID numbers were mapped to positive event ID numbers (download the file "2008-07-18.mapping" from http://www.ncedc.org/ftp/pub/doc/ncsn). In addition, on 2007/06/22 7,539 event ID numbers for earthquakes detected by NCSN real-time systems were reassigned to event ID numbers detected by the CUSP system but not yet reviewed by analysts. Most of the latter events are aftershocks of the San Simeon and Parkfield earthquakes. The association of the real-time arrival time data with the seismograms recorded by the CUSP system allows analysts to efficiently review these aftershocks and make the associated event waveform data available to the user community.
  • Channel names of seismograms (March 1984 - present) and phase data (July 1966 - present) have been mapped from a non-SEED Station Network Channel nomenclature to a SEED (Station Network Channel Location) nomenclature. The mapping of old (columns 9-12) to SEED (columns 127-129) is described in the NCSN Station List Format document. The channel name remapping includes another benefit besides the adoption of the standard SEED channel naming. We have deleted seismograms and phases from non-existent and discontinued stations, and we have renamed channels that were initially recorded under the wrong name. These now-corrected naming errors affected thousands of seismograms and phases, but probably did not corrupt many earthquake locations.
  • The NCSN/NCEDC catalog search interface now retrieves information from the NCEDC database rather than the original NCSN flat hypoinverse files.

The NCEDC apologizes for any inconvenience these changes cause. Please contact the NCEDC if you have any questions about these changes.

Bug corrected in building SEED volumes at the NCEDC

March 26th, 2008

March 26th, 2008

The NCEDC has discovered and has corrected a bug in its procedure that create SEED volumes from data at the NCEDC. Under certain circumstances, when users requested multiple segments of data for the same channel and day, the data retriever would only retrieve data for the first request segment for that channel and day, and silently ignore the other data segments requests for that channel and day.

The result is that users may not have received all of the available data when requesting multiple segments of data from the same data channel within one day. This affected both SEED volumes create for BREQ_FAST and NetDC data requests.

You may query the NCEDC waveform inventory using several methods:

SAFOD Continuous and Event data available at the NCEDC

January 9th, 2007

January 9th, 2007

The NCEDC is please to announce the availability of seismic data from the San Andreas Fault Observatory at Depth (SAFOD) component of the EarthScope Project. Earthscope is a Major Research Initiative of the National Science Foundation (NSF).

SAFOD is a deep borehole observatory that will directly measure the physical conditions under which plate boundary earthquakes occur. SAFOD is drilling and instrumenting an inclined borehole across the San Andreas Fault Zone to a depth of 3.2 km, targeting a repeating microearthquake source.

The NCEDC now has online over 800 GBytes of all available SAFOD seismic data from Jan 17, 2006 to November 16, 2006. This represents continuous seismic waveform data recording at 4000 Hz from geophones in both the SAFOD Main Hole and Pilot Hole as well as event and continuous waveforms from 250 Hz data channels acquired by the USGS Northern California Seismic Network (NCSN).

The NCEDC also has event waveform data from the SAFOD Pilot Hole from September 13, 2002 to May 30, 2004. In the near future, we will make available the remainder of SAFOD data event data from the 2004 through 2005, as well as a month of continuously recorded data of the September 28, 2004 Parkfield earthquake and its aftershocks.

The SAFOD event data and continuous 250 Hz data will be permanently archived online and permanently available from the NCEDC. The 250 Hz data is delivered in real-time to the NCEDC. The continuous 4000 Hz seismic data, stored on a multi-terabyte filesystem, will be treated as a large ring buffer, where the oldest data will eventually be taken offline to make room for newer continuous SAFOD data. The 4000 Hz data will be updated on a monthly basis as the data are delivered to the NCEDC.

All SAFOD data at the NCEDC are available through the normal NCEDC data request methods. These include NetDC, BREQ_FAST, FISSURES/DHI, STP, and the SeismiQuery web interface for data availability and instrument responses. See the following pages for more details concerning the SAFOD data set at the NCEDC.

The NCEDC also has event and continuous waveform data covering the same time periods from the Parkfield borehole High Resolution Seismic Network and the Northern California Seismic Network as well as the authoritative earthquake catalog for the region.

The NCEDC is a joint project of the University of California, Berkeley and the USGS. Please send us email at ncedcinfo@ncedc.org or fill out our comments form if you have questions or comments about these changes.

MOBB preliminary OBS data available at the NCEDC

October 30th, 2006

October 30th, 2006

The NCEDC is pleased to announce the availability of preliminary seismic, current meter, pressure timeseries from the MOBB ocean bottom seismometer (OBS) system deployed in Monterey Bay, California. The MOBB site is a joint project of the UC Berkeley Seismological Laboratory (BSL)and the Monterey Bay Aquarium Research Institute (MBARI).

The preliminary data are available in daily MiniSEED format, and can be retrieve by either HTTP or FTP protocols from the following directories:

The preliminary data has NOT had time corrections applied to the data. Time corrected data will be incorporated into the the NCEDC archive as site MOBB in the BK network.

The NCEDC is a joint project of the University of California, Berkeley and the USGS, with facilities located at the University of California, Berkeley. Please send us email at ncedcinfo@ncedc.org or fill out our comments form if you have questions or comments about these changes.


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