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).