Calpine/LBL Geysers data added to the NCEDC

April 3rd, 2004

The NCEDC is pleased to announce the availability of seismic phase and waveform data from the Calpine/Lawrence Berkeley Labs seismic network that monitors seismicity in the vicinity of the Geysers geothermal field. The phase data begins 2003/04/04. Calpine/LBL stations can be recognized with their network code of "BG".

The BG data lowers the magnitude detection threshold for earthquakes at the Geysers and improves the location accuracy. For example, for the month of January, 2003 the NCSN located 248 earthquakes at the Geysers geothermal area. In that same period in 2008 we located 1,014 earthquakes, representing a four-fold increase. The large number of earthquakes that occur at the Geysers exceeds the reviewing capabilities of the NCSN staff. Consequently, only earthquakes above M1.0 at the Geysers are reviewed by analysts. Smaller magnitude events at the Geysers that are automatically detected by the CISN software are also in the catalog, but generally not reviewed.

The dense BG network allows detection of earthquakes at the Geysers with magnitudes lower than 1.0. The algorithm to compute coda durations was not designed for “short” codas (i.e., less than 7 sec). Therefore, earthquakes with magnitudes smaller than 1.0 typically have few, if any coda durations. Consequently, these small events have Md values of zero, which represents “no magnitude”. We anticipate developing a method to compute amplitude magnitudes for earthquakes below M3.0. We will then retroactively apply this method to all historic data. We have no estimated date for completion of this effort.

There is a temporary gap in BG phase data starting 2006/11/29 when the NCSN and UCB networks migrated to CISN processing software. On 2007/07/23 the NCSN established telemetry to the Calpine data acquisition system at the Geysers. This allowed the NCSN to integrate BG data into the CISN system in near real time. We have the BG phase and waveform data for this time gap, but we have no plans to integrate it into the catalog.

We expect event waveform data from the BG network for the period 2003/04/04 – 2006/11/29 to be online by the end of 2009. BG waveform data after 2007/07/23 is available, but as events only. The bandwidth of continuous waveform data recorded by the Calpine/LBL network exceeds the bandwidth of the communications link into the NCSN system. Therefore, continuous BG data is not available at the NCEDC.

The California Integrated Seismic Network greatly appreciates the cooperation of Calpine and Lawrence Berkeley Labs in monitoring earthquakes in California and their willingess to make this data set available to the public.

NCEDC archives continuous BDSN data for the 2002/11/03 Denali earthquake

March 25th, 2004

March 25, 2004

The NCEDC has archived 2 days of continuous high frequency data from the BDSN network for the days surrounding the magnitude 7.8 Denali earthquake of November 3, 2002.

Instead of the normally triggered data at sample rates of 80 or 100 Hz, the NCEDC has archived continuous data from the HH and HL channels beginning on Nov 2 and continuing through Nov 3. This provides approximately 22 hours of data prior to the event and approximately 26 hours after the event. Two stations of the BDSN are not available in this special event archive - SAO and CMB.

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.

NCEDC archives continuous HRSN data following the 2003/12/22 San Simeon earthquake

February 27th, 2004

February 27, 2004

The NCEDC is archiving continuous high frequency data from the HRSN borehole network due to increased seismic activity following the magnitude 6.5 San Simeon Earthquake of December 22, 2003.

The NCEDC normally archives continuous 20 Hz data channnels (BPx) as well as triggered 250 Hz high-rate (DPx) data channels from the HRSN (BP network) borehole network in Parkfield. However, in response to a significant increase in earthquake detections by the HRSN network related to the San Simeon earthquake, the NCEDC is archiving continuous data from all data channels for the entire HRSN network starting on day 2003.355, the day before the earthquake, until seismic detections from the HRSN network drop to a reasonable level.

During time of normal seismic activity, continuous 20 Hz data and triggered 250 Hz data is transmitted in near-real time from the HRSN network operations center in Parkfield to the UC Berkeley Seismological Laboratory and the NCEDC. However the HRSN network has triggered ~ 50,000 times in the 68 days since between 2003.356 and 2004.059. Due to the increased seismic activity, we are writing the continuous HRSN data on tapes in Parkfield, and archiving the data from the tapes. Tape processing has introduced a delay of a month or more in the data archiving system as compared to the 1-3 day delay in archiving telemetered data.

Due to intermittent power problems with the solar powered stations and repeater site between the the HRSN stations and the central data collection site in Parkfield, there may be gaps in the continuous data from some sites.

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.

NCEDC archives continuous BDSN data for the 2003/12/22 San Simeon Earthquake

January 28th, 2004


January 28, 2004

The NCEDC has archived 7 days of continuous high frequency data from
the BDSN network for the days surrounding the magnitude 6.5 San Simeon
Earthquake of December 22, 2003.

The NCEDC normally archives continuous 20 Hz and lower data channnels (BHx,
LHx, VHx, and UHx) as well as triggered high-rate (HHx and HLx) data channels
from the BDSN (BK network) broadband and strong motion instruments. However,
in response to users' interest in this earthquake and the possibility of
induced seismicity elsewhere in other areas, the NCEDC had archived continuous
data from all data channels for the entire BDSN network for the 7 days period
spanning 2003/12/21 - 2003/12/27 (2003.355 - 2003.361).

Due to an extended telemetry problem at Parkfield, some of the data
channels from the PKD station may be either missing or available in
triggered mode during this time.

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.

NCEDC expands continuous 250 Hz archive for HRSN network

January 19th, 2004

January 19, 2004

The NCEDC has extented its continuous archive of 250 Hz data from the HRSN (BP) network with an additional 109 days of continuous 250 Hz data. Continuous 250 Hz data from 2002.228,20:00 - 2002.336,20:00 now available from the HRSN (BP) network in addition to the event-triggered 250 Hz data archive.

The HRSN normally archive continuous 20 Hz data (channels BP1, BP2, and BP3) and low frequency state-of-health (SOH) channels from the HRSN network in addition to the event-triggered 250 Hz data channels DP1, DP2, and DP3. However, continuously recorded DP1, DP2, and DP3 data channels are now available for days 2002.229,20:00 through 2002.337,20:00.

Due to telemetry problems, the 250 Hz channels for some stations and days is highly fragmented. The following table shows, for various timespans, the number of discrete time segments in the raw data that are greater than that timespan. In order to reduce the number of extremely small time segments for normal users of these data channels, the NCEDC removed any discrete timeseries segment that was less than 20 seconds in duration in its normal archive and database descriptor tables.

The full timeseries for these days, however, are available on request from the NCEDC.

			Number of segments > sieve size (in seconds)
Site  Chan Date    	     n=0     n=4     n=5    n=10    n=15    n=20
------------------------------------------------------------------------
VARB  DP1  2002.250	    1332     956     780     450     296     222
VARB  DP2  2002.250	    1659     829     678     365     231     159
VARB  DP3  2002.250	    1980     800     681     323     192     142

VARB  DP1  2002.251	    1696    1111     869     448     289     194
VARB  DP2  2002.251	    2082     906     695     345     216     130
VARB  DP3  2002.251	    2392     831     692     282     172     111

VARB  DP1  2002.252	     986     702     602     410     296     219
VARB  DP2  2002.252	    1325     739     613     372     256     196
VARB  DP3  2002.252	    1635     749     638     343     230     178

SCYB  DP1  2002.269	    2085    2085    2085    2001     957     748
SCYB  DP2  2002.269	    2085    2085    2085    1991     942     743
SCYB  DP3  2002.269	    2103    2103    2103    1863     868     718

VARB  DP1  2002.269	   10134    4890    3024    1048     485     299
VARB  DP2  2002.269	    9277    2925    2012     652     334     224
VARB  DP3  2002.269	   10538    2586    1467     503     272     182

VCAB  DP1  2002.269	     592     238     207     131      83      54
VCAB  DP2  2002.269	    1418      80      52       6       2       2
VCAB  DP3  2002.269	    1251       2       2       2       2       2

SCYB  DP1  2002.270	    2687    2686    2686    2594    1256     923
SCYB  DP2  2002.270	    2654    2653    2653    2548    1162     910
SCYB  DP3  2002.270	    2716    2715    2715    2455    1146     927

VARB  DP1  2002.270	   13985    6434    3708     963     347     162
VARB  DP2  2002.270	   12484    3446    2225     504     176      96
VARB  DP3  2002.270	   13865    2903    1429     320     119      60

SCYB  DP1  2002.271	    2968    2968    2967    2765    1233     887
SCYB  DP2  2002.271	    2962    2961    2960    2809    1216     891
SCYB  DP3  2002.271	    2976    2976    2975    2658    1136     877

VARB  DP1  2002.271	   16172    5280    2279     333      64      13
VARB  DP2  2002.271	   12864    1697     862      93      17       2
VARB  DP3  2002.271	   13550    1216     338      39       8       0

SCYB  DP1  2002.272	    2931    2931    2930    2754    1214     914
SCYB  DP2  2002.272	    2914    2914    2914    2826    1268     907
SCYB  DP3  2002.272	    2996    2996    2996    2658    1095     886

VARB  DP1  2002.272	   11717    4516    2388     614     256     136
VARB  DP2  2002.272	    9796    2077    1274     346     146      79
VARB  DP3  2002.272	   10640    1731     836     223     103      56

SCYB  DP1  2002.273	    2930    2930    2930    2767    1253     933
SCYB  DP2  2002.273	    2973    2973    2973    2865    1286     937
SCYB  DP3  2002.273	    3011    3011    3011    2686    1119     895

VARB  DP1  2002.273	   10294    2694    1145     217      82      45
VARB  DP2  2002.273	    7516     823     451     110      61      32
VARB  DP3  2002.273	    7651     567     268      84      38      22

SCYB  DP1  2002.274	    3071    3071    3071    2943    1246     897
SCYB  DP2  2002.274	    3042    3042    3042    2935    1272     938
SCYB  DP3  2002.274	    3102    3102    3102    2791    1162     923

VARB  DP1  2002.274	   11927    3886    1850     418     180     113
VARB  DP2  2002.274	    9399    1534     912     261     136      96
VARB  DP3  2002.274	   10027    1138     531     190      93      65

SCYB  DP1  2002.275	    3181    3181    3181    3075    1262     887
SCYB  DP2  2002.275	    3150    3149    3149    2986    1189     879
SCYB  DP3  2002.275	    3219    3218    3218    2896    1099     863

VARB  DP1  2002.275	   14378    5240    2802     669     233      98
VARB  DP2  2002.275	   11848    2483    1510     319     109      48
VARB  DP3  2002.275	   12750    1974     878     194      62      28

SCYB  DP1  2002.276	    3162    3160    3160    3050    1321     902
SCYB  DP2  2002.276	    3108    3107    3107    2938    1172     900
SCYB  DP3  2002.276	    3151    3150    3150    2778    1140     890

VARB  DP1  2002.276	   13412    5034    2842     854     384     213
VARB  DP2  2002.276	   11176    2556    1654     492     236     132
VARB  DP3  2002.276	   12146    2217    1143     374     171      89

SCYB  DP1  2002.277	    3175    3174    3174    3067    1301     933
SCYB  DP2  2002.277	    3158    3157    3157    3024    1218     925
SCYB  DP3  2002.277	    3165    3164    3164    2794    1140     914

VARB  DP1  2002.277	   13003    4281    2282     695     385     268
VARB  DP2  2002.277	   10248    1981    1311     496     298     195
VARB  DP3  2002.277	   10909    1779    1013     412     244     155

SCYB  DP1  2002.278	    2993    2993    2993    2892    1271     895
SCYB  DP2  2002.278	    2983    2983    2983    2846    1220     913
SCYB  DP3  2002.278	    3024    3024    3024    2700    1116     888

VARB  DP1  2002.278	   10907    3795    2150     768     449     283
VARB  DP2  2002.278	    8665    1988    1452     581     325     208
VARB  DP3  2002.278	    9428    1807    1127     431     245     153

SCYB  DP1  2002.279	    2895    2895    2895    2773    1248     930
SCYB  DP2  2002.279	    2913    2912    2912    2780    1257     939
SCYB  DP3  2002.279	    2922    2922    2922    2605    1132     913

VARB  DP1  2002.279	    8056    2946    1748     787     483     337
VARB  DP2  2002.279	    6381    1787    1372     641     380     265
VARB  DP3  2002.279	    6854    1701    1170     547     309     215

SCYB  DP1  2002.280	    2822    2821    2821    2729    1275     941
SCYB  DP2  2002.280	    2847    2846    2846    2710    1202     963
SCYB  DP3  2002.280	    2868    2868    2868    2559    1093     909

VARB  DP1  2002.280	    7252    2573    1593     764     513     374
VARB  DP2  2002.280	    5769    1696    1291     690     416     275
VARB  DP3  2002.280	    6114    1629    1168     588     342     237

SCYB  DP1  2002.281	    2755    2754    2754    2669    1270     914
SCYB  DP2  2002.281	    2761    2761    2761    2624    1157     908
SCYB  DP3  2002.281	    2800    2798    2798    2518    1123     910

VARB  DP1  2002.281	    9991    4077    2325     861     473     330
VARB  DP2  2002.281	    8741    2325    1588     622     355     244
VARB  DP3  2002.281	    9228    1904    1191     489     301     212

RMNB  DP1  2002.282	     458     327     288     133      69      44
RMNB  DP2  2002.282	     583     277     267      84      44      30
RMNB  DP3  2002.282	     616     222     171      63      35      30

SCYB  DP1  2002.282	    2855    2854    2853    2776    1367     991
SCYB  DP2  2002.282	    2810    2809    2809    2669    1250     985
SCYB  DP3  2002.282	    2823    2823    2822    2560    1202     994

VARB  DP1  2002.282	   10947    3992    2097     703     404     285
VARB  DP2  2002.282	    9801    2024    1317     514     323     215
VARB  DP3  2002.282	    9561    1592     963     438     268     185

RMNB  DP1  2002.283	     110      76      69      41      16      11
RMNB  DP2  2002.283	     137      68      62      30      17      12
RMNB  DP3  2002.283	     133      63      55      24      13       8

SCYB  DP1  2002.283	    2838    2838    2838    2739    1280     947
SCYB  DP2  2002.283	    2831    2830    2830    2713    1214     943
SCYB  DP3  2002.283	    2858    2858    2858    2566    1110     905

VARB  DP1  2002.283	   14250    5114    2535     597     240     124
VARB  DP2  2002.283	   12851    2151    1410     310     135      80
VARB  DP3  2002.283	   12347    1515     733     215      97      62

VCAB  DP1  2002.283	     429     178     164     103      61      38
VCAB  DP2  2002.283	     667     148     101      33      16       7
VCAB  DP3  2002.283	     852      46      38      13       8       6

SCYB  DP1  2002.284	    2293    2293    2293    2206    1024     743
SCYB  DP2  2002.284	    2317    2317    2317    2216     965     734
SCYB  DP3  2002.284	    2351    2351    2351    2094     891     719

VARB  DP1  2002.284	   15012    5568    2724     533     129      35
VARB  DP2  2002.284	   12439    2263    1303     202      36      11
VARB  DP3  2002.284	   13276    1739     670      96      15       4

SCYB  DP1  2002.285	    2710    2710    2710    2591    1100     797
SCYB  DP2  2002.285	    2699    2699    2699    2562    1080     788
SCYB  DP3  2002.285	    2727    2727    2726    2413     971     775

VARB  DP1  2002.285	   15984    5952    2995     597     173      71
VARB  DP2  2002.285	   14662    2596    1232     227      62      27
VARB  DP3  2002.285	   14270    1588     650     135      35      12

SCYB  DP1  2002.286	    2736    2736    2736    2609    1217     942
SCYB  DP2  2002.286	    2750    2750    2750    2661    1222     921
SCYB  DP3  2002.286	    2786    2786    2786    2488    1108     913

VARB  DP1  2002.286	   15274    4826    2358     564     308     208
VARB  DP2  2002.286	   13521    1973    1027     402     239     155
VARB  DP3  2002.286	   12430    1348     731     328     202     135

VCAB  DP1  2002.286	     755     344     311     157      81      45
VCAB  DP2  2002.286	    1727     116      58       3       2       2
VCAB  DP3  2002.286	    1533       3       2       2       2       2

SCYB  DP1  2002.287	    2729    2729    2729    2611    1215     895
SCYB  DP2  2002.287	    2720    2720    2720    2587    1178     915
SCYB  DP3  2002.287	    2733    2733    2733    2434    1107     915

VARB  DP1  2002.287	   13365    5003    2552     735     379     255
VARB  DP2  2002.287	   11062    2220    1426     473     274     200
VARB  DP3  2002.287	   11983    1854    1036     390     223     163

VCAB  DP1  2002.287	   11411    3194    2422     773     290     128
VCAB  DP2  2002.287	   18083     318     147      13       3       3
VCAB  DP3  2002.287	    7548       9       4       2       2       2

SCYB  DP1  2002.288	    2735    2734    2734    2615    1222     921
SCYB  DP2  2002.288	    2710    2710    2710    2596    1215     920
SCYB  DP3  2002.288	    2779    2779    2779    2485    1098     888

VARB  DP1  2002.288	   12577    6776    4384    1499     604     289
VARB  DP2  2002.288	   11997    4260    2940     853     346     164
VARB  DP3  2002.288	   13857    3821    2094     541     213     103

VCAB  DP1  2002.288	    3287    1355    1151     514     250     106
VCAB  DP2  2002.288	    6807     295     127       4       2       2
VCAB  DP3  2002.288	    4667       5       2       2       2       2

SCYB  DP1  2002.289	    1861    1861    1861    1768     740     547
SCYB  DP2  2002.289	    1873    1872    1872    1794     767     530
SCYB  DP3  2002.289	    1853    1853    1853    1656     684     553

VARB  DP1  2002.289	   14732    6172    3328     758     220      78
VARB  DP2  2002.289	   12770    2940    1749     335      97      39
VARB  DP3  2002.289	   14154    2315    1005     182      54      26

VCAB  DP1  2002.289	     148     112     102      71      56      41
VCAB  DP2  2002.289	     779      89      48       3       1       1
VCAB  DP3  2002.289	     872       1       1       1       1       1

VARB  DP1  2002.290	   14767    6386    3485     849     285     103
VARB  DP2  2002.290	   12919    3172    1931     384     110      36
VARB  DP3  2002.290	   14202    2527    1127     227      55      15

VCAB  DP1  2002.290	    4057    1406    1105     325     130      67
VCAB  DP2  2002.290	    8231     110      49       6       3       3
VCAB  DP3  2002.290	    2917       4       3       3       3       3

VARB  DP1  2002.291	   14621    6778    3807     926     299     114
VARB  DP2  2002.291	   13111    3474    2117     424     113      39
VARB  DP3  2002.291	   14743    2800    1253     233      54      16

VARB  DP1  2002.292	   13891    6703    3963    1106     407     169
VARB  DP2  2002.292	   12659    3680    2330     562     194      76
VARB  DP3  2002.292	   14278    3104    1517     335     120      50

VARB  DP1  2002.293	   14259    6755    3907    1062     374     167
VARB  DP2  2002.293	   12982    3592    2266     512     182      85
VARB  DP3  2002.293	   14545    3003    1471     313      99      47

VARB  DP1  2002.294	   13859    6815    4074    1174     424     166
VARB  DP2  2002.294	   12793    3743    2404     589     187      66
VARB  DP3  2002.294	   14523    3120    1534     342     101      43

MMNB  DP1  2002.295	     103      52      37      19      14      13
MMNB  DP2  2002.295	      94      46      43      21      16      10
MMNB  DP3  2002.295	      97      63      36      18       8       5

VARB  DP1  2002.295	   12456    5869    3421     885     312     116
VARB  DP2  2002.295	   11280    3183    1978     409     135      44
VARB  DP3  2002.295	   12663    2621    1208     233      61      14

CCRB  DP1  2002.296	     502     502     502     213       2       2
CCRB  DP2  2002.296	     502     502     502     261       2       2
CCRB  DP3  2002.296	     502     502     502     221       2       2

GHIB  DP1  2002.296	      62      25      16       4       2       2
GHIB  DP2  2002.296	      40      15      15       2       2       2
GHIB  DP3  2002.296	      40      10       4       2       2       2

LCCB  DP1  2002.296	     484     484     484     459       1       1
LCCB  DP2  2002.296	     484     484     484     346       1       1
LCCB  DP3  2002.296	     484     484     484     455       1       1

MMNB  DP1  2002.296	    1523     988     876     624     527     475
MMNB  DP2  2002.296	    2255    1616    1602    1036     670     408
MMNB  DP3  2002.296	    2660    2350    1667    1090     526     298

SCYB  DP1  2002.296	     507     507     507      55       2       2
SCYB  DP2  2002.296	     507     507     507     232       2       2
SCYB  DP3  2002.296	     507     507     507       2       2       2

SMNB  DP1  2002.296	    1257     436     310      50      10       5
SMNB  DP2  2002.296	     993     323     202      16       6       5
SMNB  DP3  2002.296	     727     222      85      10       6       6

VARB  DP1  2002.296	    3946     662     378     132      77      54
VARB  DP2  2002.296	    1817     299     225     101      58      35
VARB  DP3  2002.296	    1393     303     195      86      38      24

RMNB  DP1  2002.297	     127     101      81      48      39      31
RMNB  DP2  2002.297	     123      89      74      42      36      31
RMNB  DP3  2002.297	     149      98      76      41      31      24

RMNB  DP1  2002.298	    3514    1690    1618     329     122      62
RMNB  DP2  2002.298	    3712     815     475     120      64      49
RMNB  DP3  2002.298	    3468     436     304      95      55      45

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.


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