Routine Earthquake Analysis

In fiscal year 2004-2005, nearly 16,000 earthquakes were detected by the automatic systems in northern California. This compares with over 12,000 in 2003-2004 and 8,300 events in 2002-2003. The increase in the number of events can be attributed to the 2003 San Simeon and 2004 Parkfield earthquakes, both of which have had energetic aftershock sequences. Of those 15,000+ events, over 450 had preliminary magnitudes greater than 3. Fifty-five events had $M_{L}$ greater than 4. The largest event recorded by the system was the $M_{w}$7.1 event offshore of Crescent City (the largest event in the network was the Mw 6.0 Parkfield event).

As described in the 2003-2004 Annual Report, the BSL staff are no longer reading BDSN records for local and regional earthquakes (as of March 2004). This decision was based in part to reduce duplication of effort between Berkeley and Menlo Park.

The BSL continues to focus on the unique contributions that can be made from the broadband network. From July 2004 through June 2005, BSL analysts reviewed nearly 58 earthquakes in northern California and adjoining areas of magnitude 3.5 and higher. Reviewed moment tensor solutions were obtained for 65 events (through 6/30/2005). Figure 10.4 and Table 10.1 display the earthquakes located in the BSL catalog and the moment tensor solutions.


Table 10.1: Moment tensor solutions for significant events from July 1, 2004 to June 30, 2005 using a complete waveform fitting inversion. Epicentral information from the UC Berkeley/USGS Northern California Management Center. Moment is in dyne-cm and depth is in km.

Location Date UTC Time Lat. Lon. MT $M_l$ $M_w$ Str. Dip Rake Mo
Depth
Newport, OR 07/12/2004 16:45:00.0 44.332 -124.520 21 4.9 4.8 81 87 -175 1.54e23
San Simeon 07/13/2004 23:45:45.0 35.700 -121.059 5 4.1 4.1 123 51 105 1.51e22
Lakeview, OR 07/22/2004 20:26:27.0 42.212 -120.283 8 4.3 4.6 176 64 -101 8.08e22
San Simeon 07/27/2004 03:38:17.0 35.718 -121.053 5 3.9 3.7 117 53 98 3.69e21
Pinnacles 07/31/2004 10:35:54.0 36.641 -121.259 11 3.6 3.5 231 85 18 1.86e21
Newport, OR 08/19/2004 06:06:03.0 44.665 -124.300 24 4.7 4.6 159 87 8 7.96e22
Pinnacles 08/30/2004 04:30:57.0 36.578 -121.179 11 4.0 4.0 49 89 -4 1.00e22
San Simeon 08/31/2004 00:40:18.0 35.674 -121.117 5 4.0 3.8 114 53 63 6.29e21
Pinnacles 08/31/2004 09:12:27.9 36.589 -121.184 11 3.9 3.9 53 85 -11 6.58e21
Bodie 09/18/2004 07:08:00.0 37.990 -118.692 5 4.1 4.1 57 82 37 1.69e22
Bodie 09/18/2004 12:39:20.0 37.993 -118.719 5 3.6 3.6 342 72 -156 1.71e21
Bodie 09/18/2004 23:02:17.0 38.009 -118.679 8 5.4 5.5 239 89 -23 1.67e24
Bodie 09/18/2004 23:43:31.0 38.009 -118.668 5 5.3 5.4 53 88 10 1.27e24
Bodie 09/19/2004 06:58:04.0 38.008 -118.679 11 3.9 3.9 340 77 163 9.26e21
Bodie 09/20/2004 16:51:04.0 38.029 -118.644 5 4.9 4.8 244 84 -19 1.57e23
San Juan Bautista 09/22/2004 10:57:35.0 36.803 -121.535 11 3.8 3.7 53 86 -25 3.90e21
Coalinga 09/26/2004 15:54:05.0 36.155 -120.654 5 3.7 3.7 119 51 103 4.11e21
Parkfield 09/28/2004 17:15:24.0 35.815 -120.374 8 6.0 6.0 48 82 -13 9.97e24
Parkfield 09/28/2004 17:24:15.0 35.806 -120.349 5 4.7 4.7 330 83 -167 1.45e23
Parkfield 09/28/2004 19:31:27.0 35.839 -120.387 8 4.0 4.1 56 90 -11 1.38e22
Parkfield 09/29/2004 17:10:04.0 35.953 -120.502 11 5.2 5.1 236 87 6 4.45e23
Keene 09/29/2004 22:54:54.0 35.389 -118.621 11 5.0 5.0 295 89 -169 4.02e23
Parkfield 09/30/2004 18:54:28.0 35.984 -120.550 11 5.1 4.9 232 89 7 2.66e23
Templeton 10/02/2004 12:22:09.0 35.542 -120.813 8 4.3 4.1 120 48 109 1.50e22
Bodie 10/09/2004 03:45:48.0 37.980 -118.659 11 4.7 4.6 93 86 10 7.61e22
Bodie 10/10/2004 14:03:22.0 37.963 -118.661 8 3.5 3.6 185 79 164 3.19e21
Bodie 10/20/2004 11:35:15.0 38.039 -118.608 5 4.1 4.0 250 84 -45 1.13e22
Bodie 10/20/2004 12:03:11.0 38.039 -118.612 8 3.9 3.6 46 90 40 3.18e21
Gilroy 10/25/2004 19:55:38.0 39.967 -121.599 5 3.9 3.7 213 81 10 4.27e21
Geysers 10/29/2004 18:02:55.0 38.819 -122.793 5 3.8 3.8 16 56 -107 6.57e21
Parkfield 11/19/2004 02:56:00.0 35.862 -120.408 8 3.8 3.7 145 87 174 4.17e21
Pinnacles 11/24/2004 02:06:04.0 36.607 -121.209 8 4.5 4.4 222 85 6 4.18e22
Pinnacles 11/24/2004 05:23:40.0 36.600 -121.202 11 3.5 3.7 48 88 -23 3.87e21
Parkfield 11/29/2004 01:54:14.0 35.944 -120.492 8 4.2 4.2 52 85 -17 2.30e22
Willow Creek 12/05/2004 01:48:04.0 40.740 -123.802 21 3.9 4.3 181 49 -75 2.72e22
Blue Lake 12/12/2004 09:13:33.0 40.697 -123.867 27 4.1 4.3 53 72 -10 5.47e22
Pinnacles 12/15/2004 04:16:52.0 36.635 -121.253 14 3.9 3.8 227 86 14 5.11e21
Geysers 12/27/2004 10:36:23.0 38.747 -122.727 5 4.3 4.3 111 48 -72 3.13e22
Avenal 01/28/2005 13:03:26.0 36.047 -120.037 8 3.9 3.8 293 46 102 6.59e21
Alum Rock 02/05/2005 18:43:30.0 37.395 -121.487 14 4.4 4.1 333 90 -178 1.47e22
Parkfield 02/08/2005 22:00:48.0 35.952 -120.506 14 3.5 3.6 57 89 6 2.52e21
Toms Place 03/13/2005 22:09:12.0 37.453 -118.840 8 4.2 4.0 11 90 12 1.32e22
Petrolia 03/18/2005 07:23:58.0 40.370 -124.984 18 4.4 5.0 186 78 30 3.03e23
Parkfield 03/26/2005 04:36:48.0 35.838 -120.388 8 3.6 3.7 138 87 164 4.00e21
Mettler 04/16/2005 19:18:13.0 35.027 -119.178 11 5.1 4.6 249 63 80 1.05e23
Ferndale 04/28/2005 18:31:20.0 40.594 -125.580 14 3.8 4.0 110 87 -177 1.15e22
Green Valley 05/08/2005 08:43:55.0 38.378 -122.166 8 4.2 4.2 171 78 167 2.01e22
Piedmont 05/08/2005 10:35:55.0 37.840 -122.222 5 3.4 3.3 37 80 -28 1.07e21
Geysers 05/09/2005 22:37:39.0 38.786 -122.753 5 4.2 4.4 161 84 -168 3.76e22
Burney 05/10/2005 20:21:10.0 40.946 -121.757 8 4.5 4.5 152 58 -124 5.52e22
Parkfield 05/16/2005 07:24:37.0 35.928 -120.478 11 4.7 4.5 318 86 -169 6.64e22
Anza 06/12/2005 15:41:46.0 33.53 -116.58 14 5.2 5.2 304 65 174 6.48e23
Mendocino 06/15/2005 02:50:54.0 41.328 -125.868 21 0.0 7.0 225 85 13 3.79e26
Mendocino 06/15/2005 06:27:05.0 40.823 -126.489 21 4.6 4.7 207 84 -7 1.09e23
Mendocino 06/15/2005 07:14:11.0 40.905 -126.392 24 4.6 4.7 207 70 23 1.16e23
Yucaipa 06/16/2005 20:53:25.0 34.058 -117.007 11 5.3 4.9 309 48 140 2.42e23
Mendocino 06/17/2005 06:21:41.0 40.758 -126.595 21 6.6 6.7 105 80 170 1.06e26
Tahoe Vista 06/26/2005 18:45:57.0 39.310 -120.067 11 5.2 4.8 230 86 -14 1.78e23


Figure 10.4: Map comparing the reviewed moment tensor solutions determined by the BSL in the last 12 years (blue) and those from the last fiscal year (red).
\begin{figure*}\begin{center}
\epsfig{file=hrsn05_2M2s.eps, width=14cm}\end{center}\end{figure*}



Subsections

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