NCSS event review threshold change

May 27th, 2013

May 27th, 2013

The Northern California Seismic System (NCSS), operated by the US Geological Survey in Menlo Park and UC Berkeley Seismological Laboratory, locates ~20,000 earthquakes per year in the Geysers geothermal region (Figure 1).

Since 2007/07/23, when data from the Calpine stations were integrated into Northern California Seismic System real-time operations, the magnitude (M) threshold for analyst review has been M1.0, or about 4000 earthquakes per year. Automatically determined, unreviewed locations below this magnitude threshold have been available the catalog. In reality, the number of events that have required review is higher because subnet triggers (detections without a location) require analyst review to determine a location and magnitude.

To accommodate reduced staffing levels, we are increasing the review threshold to M1.2 for earthquakes above 7km depth, which should reduce the number to be reviewed by ~1500 earthquakes per year. We anticipate that this change in policy will have little impact on the quality of the catalog because the magnitude detection threshold in the Geysers has been ~M1.2 since 1975 and the accuracy of the automatically located earthquakes since 2007 is quite high due to the large number of stations in the region contributed from the BG (LBNL Geysers) Network.

The coordinates of the exclusion area (Figure 1) are:

polygon=38.83,-122.9,38.85,-122.9 38.9,-122.85,38.9,-122.78 38.78,-122.67,38.73,-122.67 38.73,-122.75,38.83,-122.9

Seismicity of the 2012 geysers

Figure 1. Seismicity in 2012 above magnitude 1.0 (orange dots), and location Geysers exclusion polygon.

Web Services - New ways to access data at the NCEDC

November 26th, 2012

November 26th, 2012

The NCEDC is pleased to announce a set of web services that provide new ways for users to query and retrieve information from the NCEDC. These services provide simple functions that can be used from a web browser, command-line programs such as curl and wget, and through programming languages such as perl, python, shell scripts, or MATLAB. The initial set of NCEDC web services provide station and channel information, channel instrument responses, and time series data.

Why web services?
Web services at the NCEDC use a RESTful (Representational State Transfer) design to provide a simple stateless query and data retrieval system. RESTful Web services use the HTTP protocol and normally communicate with clients using TCP port 80, which is the default port used by web servers. Using HTTP and standard web server ports minimizes interference from firewalls, and allows you to use web services anywhere you can use a web browser -- from behind most firewalls, and through web proxies.

New web services:
The NCEDC is initially introducing 5 web services:

The ws-station web service provides access to station metadata in the NCEDC database. The results are returned in XML format using the StationXML schema. Users can query for station metadata by network, station, channel, location, time and other search criteria and request results at multiple levels (station, channel, response).

The ws-resp web service provides access to channel response information in the SEED RESP format (as used by evalresp). Users can query for channel response by network, station, channel, location and time

The ws-availability web service returns information about what time series data is available at the NCEDC. Users can query for inventory information by network, station, channel, location, time and other search criteria. Data can be returned in three different formats: ws-bulkdataselect input, ws-dataselect query parameters and XML.

The ws-dataselect web service returns a single channel of time series data in miniSEED format. With this service you specify network, station, location, channel and a time range and the service returns miniSEED. ws-dataselect is part of the ICAB system. Data that it extracts from the NCEDC repositories can be passed to other ICAB services or can be returned directly.

The ws-bulkdataselect web service returns multiple channels of time series data in miniSEED format for specified time ranges. With this service you specify a list of selections composed of network, station, location, channel, start-time and end-time and the service streams back the selected raw waveform data. ws-bulkdataselect can handle very large selections and can be easily driven by command line programs such as wget, curl or similiar utilities.

These web services are designed to be compatible with the equivalently named web services at the IRIS DMC. Please visit the NCEDC Web Services Web Page for a complete list of NCEDC Web services and descriptions.

NSMP first generation SEED metadata available at the NCEDC

February 15th, 2012

February 15th, 2012

The NCEDC has completed the first generation of SEED metadata for instrumentation operated by the USGS National Strong Motion Project. The response information is available in various standard formats. Metadata is present for the history of each channel back to the installation of digitally recording equipment. It required careful assignment of SEED location codes to all NSMP channels to differentiate similar channels in structures. It also required review of historical records to assign serial numbers to all sensors and dataloggers. Unfortunately, sensitivities and response information are not known for some analog dataloggers, such as Kinemetrics SMA-1 recorders. The NSMP will continue efforts to document the response of historic stations, and the NCEDC will update response information to reflect changes in currently operating stations as received.

SWC - perl program for downloading waveform data from the NCEDC

May 18th, 2011

May 18th, 2011

The NCEDC is pleased to announce the introduction of the Simple Waveform Client (SWC), a command-line program for easily dowloading waveform retrieval from the NCEDC Archive and NCEDC DART (Data Available in Real Time). The NCEDC Simple Wave Client (SWC) and and companion program Simple Wave Server (SWS) at the NCEDC provide a simple interface for retrieving segments of continuous or event time series data in MiniSEED format. Data can be requested by SEED Station, Network, Channel, Location, time interval, and/or eventid.

SWC is a perl program and accomanying perl module that runs on Linux, Solaris/Unix, and MacOS systems. The NCEDC provides 2 Simple Wave Servers:

  • an sws server for archived data in the NCEDC Data Archive
  • an sws server for real-time data in the NCEDC DART (Data Available in Real Time)

Dataless SEED volumes with complete metadata for all channels are available by FTP or HTTP from the NCEDC Metadadir Directories which are organized by network code.

The swc program can be downloaded from the swc program directory. After downloading the distribution file, install the program with the following steps:

    tar xvf swc-dist-108.tar
    cd swc-dist-108

You will be prompted for several options for personal vs system-wide installation.

The syntax for the swc program is shown below.

swc  [-h] [-M] [-T|-K] [-f starttime [ -t endtime | -s timespan ]]  
	[-E eventid -D eventid_domain] [-o - | outputfile] [-e] [-d N]  
	[-S server] [-H hostname ][-P port] sncl1 ... snclN
    -h      Help - prints this help message.
    -I      Request channel Inventory (menu list) instead of waveform data.
    -T|-K   Trim waveforms to specified time (-T) or Keep data from records 
            within specified time interval (-K).  Default is -T.
    -f starttime

            Start time of waveform.
            The date and time are specified in a single string, and can
                 can be provided in one of several formats:
                The date must be fully specified.  The time portion is optional,
                and may be specified to hour, minute, second, or subsecond
    -t endtime
            End time of waveform.
    -s timespan
            Timespan of request.  Timespan is an integer string terminated 
            with one of the following characters (case sensitive).  
            If no terminater character is used, seconds are assumed.
                        S = seconds     d = days
                        M = minutes     m = months
                        H = hours       y = years
    -E eventid
            Specify an eventid for retrieving event waveforms.  
            Not all Simple Waveform Servers support retrieval by event.  
            The NCEDC DART does NOT know about events.
    -D event_domain
            Specify the domain for the eventid (NC or SC).
    -o - | outputfile
            Specifies an explicit output file, or '-' for stdout.  
            If this option is not specified, an output 
            file based on the SNCL and date_time will be created.
    -e    Output event data into a directory 
            instead of the current directory.  Does NOT override '-o' option.
    -S servername
            Generic name of waveform server. Valid servernames are:
                dart, ncedc_archive.
            Default servername is ncedc_archive.  See file 
            in home directory for configuration.
    -H hostname
            Explicit hostname or IP address of waveform server.
    -P portnumber
            Port number or port name of server.  Default port number is 4999.
    -d N    Debug value.  Current values are:
            1 = display request and response.
    sncl1 ... snclN
            A list of one or more SNCL-strings, each containing 
            dot-separated sections:
            Each section may be a single component (eg BKS) or a
	    comma-delimited list of components such as BKS,CMB or HHE,HHN,HHZ.
	    If any section contains a comma-delimited list, the SNCL-string is
	    expanded to multiple SNCLs by performing a cross-product of the
	    each components the the section with every other other section of
	    the SNCL-string.  For blank location codes, you may optionally
	    omit the .Location portion of the SNCL-string.
1.  Wildcard characters used within a SNCL must be quoted to avoid having the Unix/Linux shell 
    perform the wildcard expansion.   For Unix/Linux, use a backslash character before the  wildcard 
    character, or enclose the SNCL string in quotes.


1.  swc -S ncedc_archive -T -f 2010/02/24,05:15 -s 5M HOPS.BK.HHZ CMB.BK.HHZ

2.  swc -S ncedc_archive -T -f 2010.123,12:05:15.67 -s 5M 'HOPS,CMB.BK.BHE,BHN,BHZ.*'
       expands to the list of SNCLs:
                HOPS.BK.BHE.* HOPS.BK.BHN.* HOPS.BK.BHE.*
                CMB.BK.BHE.*  CMB.BK.BHN.*  CMB.BK.BHE.*
        The waveform server will perform the wildcard expansion.

3.  swc -S dart -T -f 2011.054,12:05:15.67 -s 5M 'CMB.BK.BHZ.*'

4.  swc -S ncedc_archive -E 71365875 -e

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 or fill out our comments form if you have questions or comments about these changes.

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 or fill out our comments form if you have questions or comments about these changes.

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