2015 wildfires take a toll on seismic monitoring

October 1st, 2015

November 1st, 2015



Figure 1: Map of stations in Northern and Central California, including NC (orange), BK (blue), CI (yellow), NP (white), and BG (pink). Not all stations of the California Integrated Seismic Network are shown. The labelled stations are the USGS that have been affected by the 2015 wildfire season as of Oct 1, 2015; a number of stations were damaged and communications were disrupted in the BG network as well. (Click to view larger.)"

In a typical year, the USGS might lose one or two seismic stations in Northern and Central California from wildfire damage. Thus far in 2015, over 30 stations operated by the USGS have been affected and an additional 30 maintained by Lawrence Berkeley National Lab in the Geysers have been affected (Figure 1). This loss of monitoring sites has had an impact on the operations of the Northern California Seismic System (NCSS), particularly in the detection and location of small events in the southern Central Valley and the Geysers area.

On September 11, 2015 at 09:30 UTC, the Butte fire damaged the Sierra Vista microwave communications link. This microwave link is responsible for bringing in 23 NCSN (Northern California Seismic Network) stations in the San Joaquin Valley. As a result, we are no longer receiving data from AAS, ABJ, AOH, ASMB, BMS, BRM, HSL, MBE, MBU, MCUB, MHD, MMI, MMT, MNHB, MPR, MRH, MSV, MYL, PAR, PDR, PHB, PJC, PJU, PKE, and PWM. These stations provide coverage in the Sierra Foothills and in the western foothills of the San Joaquin Valley. USGS Menlo Park staff visited the site with personnel from the Army Corps of Engineers (ACOE) on September 21st. We are working with ACOE to restore the link but currently do not have an estimated time for its return to operation. The loss of these stations has reduced the sensitivity of the NCSS for the detection and location of small events, as well as degrading location accuracy. The change is largest in the valley, west and slightly south of Mammoth, of ~0.7-0.8 magnitude units. This calculation was done by Corinne Bachmann, of LBNL, who studied NCSS catalog completeness as part of her Ph.D. in 2009. The new threshold is magnitude ~2.3.



Figure 2. Top is a broadscale view of the stations in the greater Geysers area; bottom is a close up showing the locations of the damaged or unknown status stations in the NC and NP networks. Pink stations are those in the BG network, which are not currently being received in real-time monitoring system. (Click to view larger.)"

In parallel, the Valley fire has affected our monitoring in the Geysers area. Beginning on September 13, 2015, we began to lose contact with stations NC.GBG, NC.GCR, NP.COB, NP.ADSP, and NP.ADS2 (Figure 2). We were able to access these sites on September 28th to assess damage. Station NC.GBG was restored on the 28th and NC.GCR was restored on the 29th. Station NP.ADSP has been destroyed. NP.ADS2 is in a building which is still standing but without power or communications. The status of NP.COB is still unknown.



Figure 3: Number of events per day in the Geysers polygon. Blue is the count of all earthquakes; red is the count of events of magnitude 1 and higher. While this figure illustrates the variability in the number of events per day, the sudden decrease on Sept 13th is associated with the loss of the NCSN stations GBG and GCR and the BG network. (Click to view larger.)"

We will provide status updates as more information becomes available.

The loss of data from the BG network, combined with the temporary loss of GBG and GCR has significantly lowered the number of events detected and located in the Geysers, as illustrated in Figure 3, which shows the number of events per day in the NCSS Geysers polygon for the month of September.

In addition to the damage to the NCSN and NSMN (National Strong Motion Network) sites, the NCSS lost contact with the stations in the BG network, operated by Lawrence Berkeley National Lab, on Sept 13th at 0955 UTC. This network of ~30 highly sensitive stations, installed as part of the Enhanced Geothermal Systems project, facilitates the location of small events in the Geysers area below magnitude 1.2. LBNL staff are working to restore stations and revive the communications links. As of Oct 1, 20 stations are being recorded and stored on a local computer.

 

Finally, two other NCSN stations have been damaged or destroyed in other fires this year - NC.NMT to the Jerusalem Fire and NC.NVA to the Wragg fire. We plan to rebuild NC.NMT in the coming weeks and are assessing our options for NC.NVA.

 

 

 

 

 

 

Data Center Outage 09/18/2015-09/19/2015

September 18th, 2015

On Friday Sep 18 2015 at approximately 19:00 PT, a small fire in the UC Berkeley campus data center triggered the building's fire suppression system. This ultimately led to the powering down of the entire data center. The NCEDC and UC Berkeley seismic and geodetic acquisition, storage, and distributions systems are housed in the campus data center, and went offline at that time.

Power and network was restored to the data center at ~ 7 AM PT on Saturday Sep 19 2015. BSL staff restored all systems and data service by 17:00 PT.

No archived data was lost. BSL staff will be retrieving missing data from the data loggers, and will archive the missing data as it is made available.

If you encounter problems with data or data services, please contact us at: ncedcinfo@ncedc.org

Timing problem at Mammoth analog stations 01/22/2015 - 01/27/2015

January 30th, 2015

January 30th, 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

EGS Catalog Geysers Magnitude Errors

January 3rd, 2015

January 3rd, 2015

The Northern California Earthquake Data Center hosts several earthquake catalogs, including the the northern California earthquake catalogs of the USGS and BSL, the worldwide earthquake catalog of the ANSS, and the Enhanced Geothermal Systems (EGS) catalog. Below please see an announcement regarding magnitude errors for four Geysers-area earthquakes in the EGS catalog:

In reviewing Geysers data, the 4 events listed below had incorrect amplitudes from one station (DEB) that had a large amount of transient electronic noise. These amplitudes were previously included in the moment magnitude calculations for the events listed below, resulting in greatly exaggerated moment magnitude estimates. The corrected magnitude estimates, computed without the erroneous DEB amplitudes, are:

Date       Time              Lat        Lon   Depth   Mag Magt  Nst Gap  Clo  RMS  SRC   Event ID
----------------------------------------------------------------------------------------------
2014/04/05 19:30:20.53  38.84790 -122.83538   2.543 0.43 (formerly 4.92)  ML    0   0    0 0.05  LBL    3383465
2014/04/05 19:52:57.37  38.84423 -122.82652   2.857 1.12 (formerly 4.87)  ML    0   0    0 0.01  LBL    3383466
2014/04/05 20:04:52.30  38.80133 -122.82338   1.035 0.45 (formerly 5.06)  ML    0   0    0 0.03  LBL    3383470
2014/04/07 01:18:36.17  38.83748 -122.78598   0.851 0.51 (formerly 4.65)  ML    0   0    0 0.04  LBL    3383663
---------------------------------------------------------------------------------------------- 

EventData Web Service for Event-Associated MiniSEED Time Series

June 30th, 2014

June 30th, 2014

The NCEDC is pleased to announce a new NCEDC web service for retrieving event-associated time series from the NCEDC. Web services provide simple functions that can be used from a web browser, command-line programs such as curl and wget, dedicated clients, and through programming languages such as perl, python, shell scripts, or MATLAB.

ncedc-eventdata
The ncedc-eventdata web service returns miniSEED time series data for the specified event from the specified earthquake catalog. In it simplest form, it returns the time series for all channels and time intervals that have been associated with the event at the NCEDC. This web services provides a functional replacement for the email-base EVT-FAST service.

The NCEDC currently supports 2 event catalogs for event-associated time series events: the NCSS and the EGS catalogs.

Using the GET method, you can optionally restrict which data channels to retrieve by specifying a (wildcarded) selection of SEED Network, Station, Location, and Channel names, and an optional start time and end time for the time series. Using the POST method, you can specify a list of (wildcarded) channel names, a global restricted time window, and specific restricted time window for each specified channel. Each ncedc-eventdata web service request can only request data for a single event. You can easily generate and submit ncedc-eventdata requests using command line programs such as wget, curl, MATLAB, or dedicated client programs provided by the NCEDC.

Client programs for the ncedc-eventdata web service
FetchEventData
The program FetchEventData is a command-line fetch script that uses the ncedc-eventdata service to event-associated time series for the specified eventid from the specified catalog. Its command-line options provide support for all of the ncedc-eventdata selection options.

mssplit
The program mssplit is used to split a stream of MiniSEED records into a separate file for each data channel. It can optionally create a new directory for these data files. It can read data from either from a file or from stdin.

Examples

FetchEventData -E 72099881 -C NCSS | mssplit -D NCSS.72099881

Will retrieve all time series data for the eventid 72099881 in the NCSS catalog, create a directory named NCSS.72099881, and save each data channel in a file named with the station, network, channel, location, and start time in the specified directory.

FetchEventData -E 72099881 -C NCSS -o msfile ; mssplit -D NCSS.72099881 msfile 

Will retrieve all time series data for the eventid 72099881 in the NCSS catalog, saving all data channels info a file name msfile. The mssplit program then splits the specified MiniSEED file into separate channel files in the specified directory.

The mssplit program can be used to split any multi-channel MINISeed file, such as those retrieved using FetchData or FetchData-ncedc.

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.

Please visit the NCEDC Web Services Web Page for a complete list of NCEDC Web services and descriptions.


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