NCEDC News/Blog
Revision of NCSN Catalog
Categories: Northern California Seismic System (NCSS) | Magnitude Errors | Bugs | USGS Northern California Seismic Network (NCSN) | Magnitude | Earthquake Depths | Earthquake Catalogue | Catalogs | Earthquake Locations
April 20, 1997
April 29, 1997On April 29, 1997, the USGS Northern California Seismic Network (NCSN) revised the format and relocated the entire earthquake catalog at the Northern California Earthquake Data Center. We undertook the catalog revision for the following reasons:
- Revision of station names to universal format
- Completion of GPS survey of NCSN site locations
- Removal of phase information with suspect coda durations
- Assignment of new event identification numbers
- Creation of new or adjustment of existing station traveltime
Because we did not change the location procedure or velocity models, the new locations and magnitudes are nearly identical to the old locations. Minor changes result from the new station coordinates and traveltime corrections. An analysis of changes in horizontal and vertical location, origin time, rms, and magnitude for the more than 200,000 earthquakes occurring in the sample period 1980-1989 (Figure 1) shows the median changes are nearly zero. Information on the change in location or magnitude for any earthquake is available upon request from Lind Gee, lgee@usgs.gov.
The following discussion provides more detail on why we made the changes to the catalog and provides supporting documentation. For more information on the NCSN network and processing procedures, see Oppenheimer et. al. (1992).
Universal station format
A new station name format was implemented because the old format did not uniquely define a station name and component. Consequently, it was difficult to combine phase information from other seismic networks with NCSN data and fully describe the type of instrumentation deployed by the NCSN. The old format designated a station by a 3-letter name, a one-letter seismic network code, and a 1-letter component code. The Universal code designates a station and component with a combination of a 5-letter site name, a 2-letter network code, and a 3-letter component code. The new phase format based on the Universal format is quite similar to the old format, and most users are unlikely to be affected by this change. A complete description of the NCSN format is available.
GPS survey of station coordinates
In April 1994 the NCSN began a systematic effort to survey all sites in the network using GPS. The effort was an adjunct to normal site maintenance visits, so the effort took more than 3 years to complete. The datum is WGS-84, versus the 1927 North American datum previously used. Uncertainty in the GPS coordinates is approximately 3 m. The mean horizontal shift is about 100 meters, though there were several sites that were mislocated by more than 500 meters (Table 1). However, the shift in datum produces a change in epicentral position of 84 - 101 m to the west and an elevation change of -15 to -20 m. Greater shifts are likely due to incorrect determination of the original site coordinates.
We obtained GPS coordinates only for NCSN sites operating since 1994. We do not anticipate obtaining GPS coordinates for discontinued sites and portable installations for previous special studies. Site coordinates are available.
Sites with GPS coordinates can be recognized in this file as those sites for which the "latitude/longitude minutes" filed has a precision of 4 significant digits to the right of the decimal place. As shown in Figure 1, the GPS coordinates do not greatly change the earthquake locations.
 |
|
| Figure 1. Histograms of earthquake location differences (old - new). Median values are shown above each plot. dt is the difference in origin time in seconds. dx is the absolute difference in epicentral (horizontal) position in km. dz is the absolute difference in vertical position in km. dm is the difference in magnitude drms is the difference in solution rms in seconds (positive values indicate improvement in solution fit). |
Suspect coda durations
The NCSN computes a duration magnitude (Md) for almost every earthquake in the catalog. We discovered that an algorithm in one of our processing systems computed coda durations for seismograms in which there were no P or S arrival times or any amplitude observations. We consider it unlikely that a seismogram would have a reliable coda duration if the arrival time information was unreliable. Further examination showed that the suspect coda durations from these seismograms were inconsistent with durations from seismograms that had traveltime observations. In particular, the suspect durations tended to cause the computed (Md) to be too large. Consequently, we removed these suspect readings from the catalog. Their removal affected only the magnitude of a small number of earthquakes.
Assignment of new event identification numbers
Event identification numbers were re-assigned to the class of 218,026 earthquakes without associated digital seismograms. This class of data includes all earthquakes in the catalog with origin times before 1984, earthquakes from other seismic networks, and earthquakes from the NCSN Real-Time-Picker earthquake system that operated from 9/81 to 3/97. Event identification numbers of earthquakes processed by the CUSP system remain unchanged. These new numbers are negative and decrease (i.e., increase in the negative direction) with increasing origin time. A mapping of old-to-new event identification numbers is available upon request from Lind Gee at lgee@usgs.gov.
Station traveltime corrections
As a result of the new site locations, we derived traveltime corrections for all stations in the NCSN catalog. To derive these corrections, we first relocated the entire catalog with the GPS station coordinates. We used the same location procedure, velocity models, and station traveltime corrections described in Oppenheimer et. al. (1992). We then adjusted the existing station traveltime correction with the mean traveltime residual for each station. If no correction existed for a station, the mean residual became the new station correction. The latter situation most often occurred for stations installed subsequent to the time when the velocity model was developed. We then relocated the catalog again with the new traveltime corrections. The new traveltime corrections are available from Lind Gee at lgee@usgs.gov.
Table 1. NCSN COORDINATE SHIFTS
OBSERVED EXPECTED
DX AZIMUTH DZ DX AZIMUTH DZ
km deg m km deg m
____________________________________________________
AAR 0.129 79 -19 0.093 84 -18
AAS 0.095 99 -34 0.092 84 -18
ABJ 0.164 107 -23 0.093 83 -18
ABR 0.348 161 -25 0.094 83 -18
ADW 0.109 77 -23 0.092 84 -18
AFD 0.369 308 -44 0.093 84 -18
AFH 0.381 57 -25 0.092 84 -18
AFR 0.068 79 -21 0.093 84 -18
AHR 0.145 113 -5 0.093 84 -18
ALA 0.082 126 -30 0.091 84 -18
ALN 0.091 311 -27 0.093 84 -18
AOD 0.150 85 -16 0.091 84 -18
AOH 0.178 126 -47 0.095 83 -18
APR 0.094 92 -20 0.093 84 -18
ARJ 0.113 76 -23 0.091 84 -18
ARR 0.067 55 -27 0.093 84 -18
ASM 0.153 109 -54 0.092 84 -18
AVR 0.094 77 -19 0.093 84 -18
BAP 0.532 163 -26 0.094 87 -16
BAV 0.031 114 -32 0.092 86 -17
BBG 0.074 56 -32 0.092 86 -17
BBN 0.082 93 -30 0.092 86 -17
BCG 0.066 220 -55 0.094 86 -16
BCW 0.081 75 -13 0.093 87 -16
BEH 0.110 98 -8 0.093 86 -17
BEM 0.075 67 -24 0.093 86 -17
BHR 0.245 81 -38 0.093 86 -16
BJC 0.109 99 -34 0.094 86 -16
BJO 0.063 105 -31 0.093 86 -16
BLR 0.077 130 -43 0.094 86 -16
BMS 0.098 95 -31 0.092 86 -17
BPC 0.173 154 -10 0.094 86 -16
BPI 0.097 94 -28 0.092 86 -16
BPO 0.098 71 -24 0.095 87 -16
BPR 0.095 99 -30 0.095 87 -16
BRM 0.118 93 -29 0.093 86 -17
BRV 0.072 77 -16 0.093 86 -17
BSG 0.132 90 -31 0.092 86 -16
BSL 0.133 150 -13 0.093 86 -16
BSM 0.132 109 -55 0.093 87 -16
BSR 0.180 125 -20 0.094 86 -16
BVL 0.101 73 -31 0.092 86 -16
BVY 0.406 32 62 0.093 86 -16
CAD 0.162 88 -55 0.094 85 -16
CAI 0.047 89 -36 0.098 85 -16
CAL 0.103 47 -14 0.095 86 -16
CAO 0.201 62 -6 0.094 85 -16
CBR 0.096 111 -30 0.095 85 -16
CBS 0.071 100 -30 0.094 85 -17
CBW 0.085 84 -20 0.094 84 -16
CBZ 0.148 66 -30 0.094 85 -16
CCO 0.193 108 -37 0.095 86 -16
CCY 0.020 51 -46 0.095 85 -16
CDA 0.179 106 -23 0.094 85 -16
CDO 0.086 95 -29 0.094 85 -16
CDU 0.076 109 -8 0.095 85 -16
CDV 0.083 257 12 0.093 85 -16
CGP 0.098 94 -29 0.094 85 -16
CGP1 0.098 94 108 0.094 85 -16
CLC 0.106 95 -26 0.097 85 -16
CMC 0.087 81 -38 0.095 85 -16
CMH 0.118 66 -15 0.095 85 -16
CMJ 0.259 75 -19 0.095 85 -16
CMK 0.113 51 -48 0.093 85 -16
CML 0.129 99 -21 0.095 85 -16
CMN 0.113 245 -36 0.094 84 -16
CMO 0.108 72 -47 0.095 85 -16
CMP 0.864 90 -39 0.093 85 -17
CMR 0.094 112 -30 0.096 85 -16
CNI 0.051 104 -31 0.094 85 -16
COS 0.107 61 -48 0.093 85 -17
CPI 0.083 96 -23 0.096 85 -16
CPM 0.074 95 -22 0.097 84 -16
CRP 0.088 102 -28 0.094 85 -16
CSA 0.180 322 -38 0.094 85 -16
CSL 0.086 77 -27 0.095 85 -16
CSP 0.069 53 -37 0.096 85 -16
CSV 0.325 103 -39 0.094 85 -16
CVA 0.154 83 -27 0.096 85 -16
CVL 0.311 12 68 0.094 86 -16
CVP 0.108 90 -41 0.095 85 -16
CYB 0.087 80 -30 0.097 85 -16
GAC 0.066 81 -17 0.098 84 -16
GAX 0.196 85 -12 0.098 84 -16
GBD 0.137 111 -23 0.098 83 -16
GBG 0.289 98 -22 0.098 84 -16
GCB 0.845 170 39 0.100 83 -16
GCR 0.090 46 -38 0.098 84 -16
GCV 0.041 175 -25 0.098 84 -16
GCW 0.106 89 -39 0.098 83 -16
GDC 0.114 127 -36 0.097 84 -16
GDX 0.080 98 -21 0.098 84 -16
GGP 0.066 80 -31 0.098 84 -16
GGU 0.031 68 -16 0.099 84 -15
GHC 0.082 88 -41 0.097 84 -16
GHG 0.022 354 -32 0.097 84 -16
GHL 0.068 102 -13 0.098 84 -16
GHM 0.086 74 -30 0.097 83 -16
GHO 0.079 87 -16 0.099 84 -16
GHV 0.136 105 -11 0.096 83 -16
GMC 0.182 263 -5 0.098 84 -16
GMK 0.063 95 -2 0.096 84 -16
GNA 0.103 90 -26 0.100 83 -16
GPM 0.279 1 -71 0.097 84 -16
GRT 0.124 90 -29 0.098 84 -16
GSG 0.121 320 -23 0.098 84 -16
GSN 0.068 81 -21 0.099 83 -16
GSS 0.068 95 -8 0.097 84 -16
GTS 0.076 85 -34 0.096 83 -17
GWK 0.122 98 -17 0.096 84 -16
GWR 0.192 32 -4 0.100 83 -16
HAZ 0.104 77 -24 0.095 86 -16
HBT 0.111 91 -30 0.094 87 -16
HCA 0.077 93 -32 0.094 86 -16
HCO 0.342 71 -14 0.095 86 -16
HCR 0.116 5 -37 0.095 86 -16
HDL 0.110 79 -25 0.093 86 -16
HER 0.081 78 -30 0.095 86 -16
HFE 0.161 72 -33 0.094 86 -16
HFP 0.105 83 -47 0.093 86 -16
HGS 0.105 68 -1 0.093 86 -16
HJG 0.086 116 -50 0.094 86 -16
HJS 0.063 190 -53 0.093 86 -16
HLT 0.104 98 -3 0.093 86 -16
HMO 0.029 22 -14 0.096 86 -16
HOR 0.683 107 -59 0.095 86 -16
HPH 0.033 341 -52 0.094 86 -16
HPL 0.103 77 -27 0.094 86 -17
HSF 0.113 69 -27 0.094 86 -16
HSL 0.053 78 -32 0.093 86 -17
HSP 0.126 82 -24 0.094 86 -16
JAL 0.126 59 -30 0.095 86 -16
JBC 0.592 147 1 0.095 86 -16
JBG 0.135 150 -23 0.096 86 -16
JBL 0.117 48 -42 0.096 86 -16
JBM 0.169 40 -59 0.096 85 -16
JBZ 0.108 109 -34 0.095 86 -16
JCB 0.097 69 -31 0.095 86 -16
JCH 0.116 92 -33 0.097 85 -16
JCP 0.109 99 -33 0.096 85 -16
JEC 0.097 82 -39 0.094 86 -16
JEG 0.099 76 -33 0.097 85 -16
JEL 0.083 92 -30 0.095 86 -16
JHL 0.122 94 -67 0.095 85 -16
JHP 0.221 88 -6 0.096 86 -16
JJR 0.112 80 -30 0.097 85 -16
JLX 0.112 96 -26 0.095 85 -16
JMG 0.195 106 -40 0.096 85 -16
JMP 0.081 84 -16 0.096 85 -16
JPL 0.156 109 -66 0.095 86 -16
JPP 0.145 45 -47 0.096 85 -16
JPR 0.042 147 -24 0.097 85 -16
JPS 0.072 11 -40 0.096 85 -16
JRG 0.137 130 -6 0.095 86 -16
JRR 0.089 78 -9 0.094 86 -16
JSA 0.257 84 14 0.097 85 -16
JSB 0.544 18 -14 0.096 85 -16
JSC 0.052 63 -28 0.096 86 -16
JSF 0.169 292 -31 0.096 85 -16
JSG 0.088 129 -32 0.096 85 -16
JSJ 0.087 86 -30 0.095 85 -16
JSM 0.097 91 -9 0.096 86 -16
JSS 0.103 90 -25 0.095 85 -16
JTG 0.124 88 -49 0.095 86 -16
JUC 0.051 73 -21 0.096 86 -16
JUM 0.119 81 -21 0.095 86 -16
KBB 0.130 96 -38 0.100 82 -16
KBN 0.094 69 -34 0.098 82 -16
KBR 0.136 314 -58 0.099 82 -16
KBS 0.107 49 -14 0.099 83 -16
KCP 0.179 58 -10 0.099 83 -16
KCR 0.181 94 -23 0.098 82 -16
KCS 0.112 104 0 0.098 82 -16
KEB 0.108 73 -25 0.100 79 -17
KFP 0.102 72 -28 0.098 83 -16
KGM 0.045 276 -11 0.099 82 -16
KHB 0.103 73 -21 0.098 82 -17
KHM 0.075 75 -33 0.099 82 -16
KIP 0.074 67 -26 0.099 83 -16
KJJ 0.125 78 -32 0.100 82 -16
KKP 0.112 88 -18 0.099 82 -16
KMP 0.043 118 -26 0.101 82 -16
KOM 0.083 82 663 0.097 81 -17
KPP 0.098 77 -24 0.098 82 -16
KRK 0.134 105 -21 0.098 83 -16
KRM 0.097 106 -33 0.099 81 -17
KRP 0.147 353 -18 0.100 81 -16
KSC 0.070 100 -19 0.101 80 -17
KSM 0.138 141 -60 0.100 82 -16
KSP 0.102 173 -60 0.098 83 -16
KSX 0.077 90 -23 0.099 81 -17
KTR 0.089 76 -31 0.098 80 -17
LAS 0.088 91 -13 0.093 81 -19
LBF 0.053 98 -21 0.094 82 -18
LBK 0.184 78 -37 0.098 81 -17
LBP 0.188 16 -32 0.098 82 -17
LCF 0.195 85 -19 0.092 82 -18
LCM 0.131 94 -23 0.095 83 -18
LDB 0.156 64 -52 0.095 82 -18
LGB 0.133 137 -9 0.095 81 -18
LGM 0.102 68 47 0.095 81 -19
LGP 0.073 71 -25 0.097 82 -17
LHC 0.270 73 -8 0.093 82 -18
LHE 0.095 96 -38 0.096 81 -18
LHK 0.261 2 -46 0.092 82 -19
LME 0.100 77 19 0.093 82 -18
LMH 0.104 70 -27 0.095 81 -19
LMP 0.052 171 -16 0.096 81 -18
LPD 0.201 34 -20 0.094 81 -18
LPK 3.583 89 -28 0.097 81 -18
LRB 0.090 83 -33 0.097 83 -17
LRD 0.235 195 33 0.093 83 -18
LRR 0.626 270 -24 0.094 82 -18
LRS 0.050 91 -9 0.093 82 -19
LSF 0.088 91 -13 0.096 82 -17
LSH 0.149 97 -24 0.096 82 -18
LSL 0.055 46 -44 0.092 82 -18
LSM 0.407 16 -8 0.093 82 -18
LSR 0.110 78 -15 0.096 81 -18
LTC 0.112 95 -24 0.095 82 -18
LWH 0.414 47 -16 0.094 82 -18
MBE 1.902 3 -33 0.087 86 -19
MBU 3.627 270 -17 0.090 86 -18
MCD 0.149 85 -19 0.084 86 -20
MCL 0.097 100 -49 0.087 86 -20
MCM 0.052 23 -41 0.086 86 -20
MCS 0.113 83 -21 0.087 85 -20
MCU 0.222 104 -27 0.092 85 -18
MDC 0.039 28 -27 0.086 85 -20
MDP 0.064 103 -25 0.087 85 -19
MDR 0.086 23 -29 0.086 85 -20
MEM 0.062 59 -22 0.086 85 -20
MFB 0.055 68 -18 0.084 86 -20
MGP 0.104 85 -18 0.085 85 -20
MHD 0.638 13 -30 0.089 85 -18
MLC 0.184 195 -79 0.087 85 -20
MLH 0.251 60 -20 0.086 85 -20
MLK 0.138 78 24 0.086 85 -20
MLM 0.096 23 -39 0.086 86 -20
MMI 0.110 67 -7 0.090 85 -19
MMP 0.070 62 -52 0.086 85 -20
MMS 0.096 81 -16 0.087 85 -20
MMT 0.145 99 -37 0.086 86 -19
MNH 0.099 84 -30 0.093 85 -18
MOY 0.160 72 -28 0.092 85 -18
MPR 0.067 88 -25 0.089 85 -18
MRC 0.239 164 -7 0.085 85 -20
MRD 0.125 90 -33 0.087 85 -19
MRF 0.220 275 -51 0.092 85 -18
MSK 0.057 78 -3 0.086 86 -20
MSL 0.139 92 -51 0.086 85 -20
MST 0.207 74 -14 0.090 85 -18
MTC 0.095 82 -27 0.086 85 -20
MTU 0.029 311 -18 0.085 86 -20
MWB 0.143 66 -16 0.084 86 -20
MYL 0.107 79 -32 0.090 85 -18
NAD 0.066 84 -26 0.095 84 -17
NAP 0.093 5 -18 0.096 84 -16
NBO 0.122 96 -22 0.098 85 -16
NBP 0.120 107 -32 0.096 84 -17
NBR 0.102 100 -31 0.096 84 -16
NCF 0.062 71 -23 0.097 85 -16
NCP 0.158 78 -35 0.096 84 -17
NDH 0.040 80 -27 0.096 84 -17
NFR 0.106 79 -44 0.098 84 -16
NGV 0.091 69 -31 0.095 84 -16
NHF 0.088 87 -22 0.098 85 -16
NHM 0.355 94 -32 0.094 85 -17
NIM 0.091 98 -89 0.096 84 -16
NLH 0.352 160 3 0.096 84 -16
NLN 0.074 98 -24 0.096 84 -16
NMC 0.047 84 -29 0.098 84 -16
NMH 0.090 83 -12 0.097 84 -16
NMI 0.261 23 -30 0.096 85 -16
NMT 0.148 94 -10 0.097 84 -16
NMW 0.039 65 -15 0.097 84 -16
NOL 0.166 21 -20 0.096 84 -16
NPR 0.119 91 -32 0.099 85 -15
NPV 0.121 100 -26 0.096 84 -16
NRR 0.074 110 -16 0.096 84 -17
NSH 0.094 80 -21 0.097 84 -16
NSP 0.065 82 -29 0.096 84 -16
NTA 0.303 73 -22 0.098 85 -16
NTB 0.061 39 -13 0.097 84 -16
NTY 0.099 66 -32 0.096 84 -16
NVA 0.161 100 -63 0.096 84 -16
NVE 0.872 117 77 0.096 84 -16
NWR 0.067 97 -17 0.097 84 -16
OBH 0.242 64 -8 0.093 83 -18
OCM 0.054 147 -27 0.095 83 -18
OGO 0.108 98 -3 0.094 84 -18
OHC 0.110 64 -21 0.094 84 -18
ORA 0.163 122 -24 0.094 83 -18
ORD 0.089 19 -19 0.093 83 -18
OST 0.096 147 -27 0.094 83 -18
OSU 0.120 89 -33 0.095 83 -17
OWY 0.080 108 -34 0.094 83 -18
PAB 0.140 111 -57 0.091 88 -17
PAD 0.189 115 -41 0.093 87 -17
PAG 0.106 121 -46 0.090 88 -17
PAN 0.047 202 -25 0.093 87 -16
PAP 1.942 14 29 0.093 87 -16
PAR 0.070 100 -33 0.090 86 -17
PBI 0.118 94 -39 0.090 88 -17
PBP 0.109 107 -25 0.090 88 -17
PBW 0.241 140 -79 0.092 86 -17
PCA 0.116 80 -26 0.091 87 -17
PCB 0.121 83 -22 0.092 87 -16
PCH 0.165 101 0 0.091 87 -17
PCR 0.103 72 -35 0.090 87 -17
PDR 0.122 94 -60 0.091 87 -17
PFR 0.176 74 310 0.091 87 -17
PGH 0.138 63 -28 0.090 87 -17
PHA 0.023 154 -57 0.090 88 -17
PHB 0.144 84 -21 0.090 87 -18
PHC 0.110 90 -12 0.093 88 -16
PHF 0.097 77 -36 0.091 87 -17
PHO 0.266 327 -52 0.091 87 -17
PHP 0.701 38 -19 0.091 87 -17
PHR 0.054 93 -25 0.092 87 -17
PHS 0.093 64 -24 0.093 87 -16
PIR 0.515 87 -53 0.089 87 -17
PJL 0.245 107 -50 0.094 87 -16
PKE 0.077 48 -44 0.090 87 -18
PKY 0.094 102 -31 0.092 88 -17
PLO 0.044 64 -57 0.092 87 -16
PMC 0.063 170 -17 0.092 87 -17
PMG 0.024 281 -43 0.092 88 -17
PML 0.078 66 -26 0.091 88 -17
PMM 0.106 80 -34 0.090 87 -17
PMP 0.236 104 -30 0.091 87 -17
PMR 0.115 59 -14 0.090 87 -17
POP 0.119 134 -39 0.090 87 -17
PPB 0.162 108 -44 0.092 88 -16
PPC 0.092 91 -46 0.091 87 -17
PPG 0.070 55 -38 0.090 87 -18
PPT 0.289 108 -25 0.091 87 -17
PRC 0.192 300 -48 0.091 87 -17
PSA 0.111 47 -34 0.092 87 -17
PSC 0.145 91 -35 0.090 88 -17
PSM 0.167 55 -31 0.091 87 -17
PSR 0.179 6 -72 0.090 88 -17
PST 0.615 110 -57 0.091 87 -17
PTA 0.104 79 -27 0.091 88 -17
PTQ 0.235 105 -31 0.092 89 -17
PTR 0.202 74 -49 0.089 87 -17
PVC 0.060 97 -16 0.091 87 -17
PWK 0.070 90 -33 0.091 88 -17
PWM 0.124 82 -27 0.090 87 -18
VRC 0.000 0 0 0.095 80 -18
NCEDC News
-
: Entire NCEDC Dataset Now Available Through AWS
-
: Current issue with ObsPy FDSN web service client
-
: FTP service to be retired on May 31, 2022
Categories
- 2003 San Simeon Earthquake (5)
- 2004 Parkfield Earthquake (3)
- Berkeley Digital Seismic Network (BDSN, BK) (11)
- Bugs (6)
- Calpine/LBL Geysers data (BG) (8)
- Catalogs (21)
- Data Access Methods (19)
- Data Availability (32)
- Data Center Operations (26)
- Data Center Outages (9)
- Data Distribution (3)
- Data Holdings (16)
- Earthquake Catalogue (21)
- Earthquake Depths (3)
- Earthquake Locations (9)
- High Resolution Seismic Network (HRSN, BP) (4)
- Magnitude (10)
- Magnitude Errors (4)
- Metadata (4)
- Northern California Earthquake Data Center (NCEDC) (14)
- Northern California Seismic System (NCSS) (7)
- Northern Hayward Fault Network (NHFN, BK) (3)
- SEED format (6)
- Sampling Rate (3)
- Strain Data (3)
- The Geysers (5)
- Timing Errors (3)
- U.S. Geological Survey (USGS) (3)
- UC Berkeley Seismological Laboratory (BSL) (4)
- USGS Northern California Seismic Network (NCSN) (11)
- Uncategorized (4)
- Waveform Data (33)
- Web Services (5)