$M_{L}$ and $M_{w}$

The REDI system has routinely produced automatic estimates of moment magnitude ($M_{w}$) for many years. However, wary of complications caused by the publication of multiple magnitudes, these estimates were not routinely used as the ``official" magnitude until after the 05/14/2002 Gilroy earthquake ($M_{w}$ 4.9, $M_{L}$ 5.1). Since then, solutions that meet a minimum quality criterion are automatically reported (a variance reduction of 40% or higher). This criterion appears to work very well and screens out events contaminated by teleseisms. Over the last few years, nearly all events over 4.5 have met this criterion, as have a number of events in the M3.5-4.5 range. As part of the effort to establish a statewide magnitude reporting hierarchy, we have looked more closely at the estimates of $M_{w}$ (Gee et al., 2003b; 2004) and the comparison between $M_{w}$ and $M_{L}$.

Two methods of determining regional moment tensor (RMT) solutions were originally part of the REDI system - the complete waveform modeling technique (CW) of Dreger and Romanowicz (1994) and the surface wave inversion (SW) of Romanowicz et al. (1993). In FY05/06, processing for the SW algorithm was discontinued, however CW moment tensors continue to be calculated, reviewed and reported. Comparison between the results of the CW method and other regional moment tensor studies in northern California and the western United States show excellent agreement in the estimate of seismic moment and $M_{w}$.

As we transition toward statewide reporting of earthquake information, a comparison of magnitudes calculated for Southern and Northern California becomes important. We have collected a set of events recorded well by digital broadband and and strong motion stations of the Northern California (NC), Berkeley (BK) and Southern California (CI) networks and are assessing the computation of local magnitude for each station. Reseacrh Study 2.13. reports on these activities.

Table 3.19: Moment tensor solutions for significant events from July 1, 2006 through June 30, 2007 using a complete waveform fitting inversion. Epicentral information is from the UC Berkeley/USGS Northern California Earthquake 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
Offshore of Fort Ross	7/6/2006	20:43:24	38.508	-123.463	5	3.7	3.7	4.69E+21	295	46	84
Petrolia	7/19/2006	11:41:43	40.281	-124.426	30	4.7	5	3.53E+23	102	83	173
Glen Ellen	8/3/2006	3:08:12	38.363	-122.589	5	4.7	4.4	5.64E+22	256	86	19
Bishop	9/7/2006	1:38:59	37.31	-118.284	8	3.6	3.4	1.86E+21	342	86	158
Willits	9/26/2006	20:56:13	39.31	-123.217	8	3.9	3.9	9.52E+21	333	61	-171
Petrolia	10/17/2006	20:53:18	40.55	-126	11	4.9	4.8	2.03E+23	277	85	-166
Geysers	10/20/2006	17:00:08	38.867	-122.7873	5	4.5	4.6	9.88E+22	254	68	-39
Geysers	10/20/2006	23:31:39	38.867	-122.783	5	4.5	3.8	6.50E+21	240	55	-65
Petrolia	10/24/2006	14:26:43	40.403	-125.066	5	4	4.4	4.50E+22	99	85	182
Willits	11/9/2006	8:38:13	39.355	-123.285	8	4	4	1.49E+22	336	87	172
Willits	11/10/2006	5:05:56	39.357	-123.282	8	3.7	3.7	4.69E+21	329	90	-167
Paso Robles	11/30/2006	4:06:40	35.631	-120.754	8	4.7	3.8	5.33E+21	245	89	7
Coalinga	12/16/2006	6:14:05	36.174	-120.292	5	4.3	4.2	2.16E+22	299	71	89
Petrolia	12/17/2006	15:13:40	40.392	-125.023	5	3.9	4.3	3.57E+22	274	90	-159
Bishop	12/19/2006	15:21:42	37.493	-118.188	5	4	3.7	4.33E+21	221	86	-27
Berkeley	12/21/2006	3:12:28	37.86	-122.237	8	3.7	3.6	2.85E+21	49	80	-14
Berkeley	12/23/2006	6:49:57	37.862	-122.237	11	3.7	3.6	2.82E+21	139	89	-153
Berkeley	12/23/2006	17:21:15	37.861	-122.235	11	3.5	3.4	1.63E+21	148	86	-169
Glen Ellen	1/12/2007	11:27:50	38.391	-122.615	11	3.8	3.7	3.27E+23	236	89	34
Bishop	1/17/2007	14:01:08	37.408	-118.531	5	4	3.6	3.66E+21	37	83	17
Morgan Hill	1/17/2007	17:43:22	37.12	-121.523	8	3.5	3.4	1.38E+21	328	89	-159
Petrolia	1/24/2007	13:42:52	40.312	-124.584	18	3.7	4.4	5.05E+22	187	85	25
San Simeon	2/20/2007	16:46:13	35.78	-121.382	8	3.7	3.7	4.96E+21	151	59	137
Berkeley	2/24/2007	23:46:15	37.865	-122.241	11	3.4	3.3	1.15E+21	154	88	-176
Ferndale	2/26/2007	12:19:54	40.647	-124.864	8	5	5.4	1.48E+24	60	89	-4
Lafayette	3/2/2007	4:40:00	37.901	-122.098	14	4.4	4.2	2.77E+22	82	89	-1
Bridgeport	3/9/2007	3:17:32	38.428	-119.367	11	5	4.7	1.29E+23	349	65	-114
Petrolia	4/5/2007	22:54:29	40.311	-124.578	18	3.8	4.1	1.93E+22	12	88	18
Ferndale	4/7/2007	23:55:03	40.616	-124.753	18	3.7	4.1	2.00E+22	256	78	21
Geysers	4/24/2007	21:08:28	38.796	-122.794	5	4.4	4.4	4.62E+22	342	82	-160
Geysers	4/30/2007	15:51:28	38.82	-122.823	5	3.1	3.7	3.89E+21	136	58	-133
Markleeville	4/30/2007	21:57:32	38.72	-119.62	5	3.5	3.1	5.66E+20	226	87	47
Petrolia	5/9/2007	7:50:05	40.376	-125.014	11	5	5.2	7.81E+23	188	85	24
Bishop	5/26/2007	8:04:12	37.416	-118.525	8	3.5	3.3	1.24E+21	59	81	10
Mammoth	6/12/2007	7:22:36	37.5425	-118.8677	11	3.6	3.6	3.14E+21	140	82	-143
Mammoth	6/12/2007	7:23:43	37.539	-118.876	14	5.1	4.6	9.96E+21	310	82	172
Offshore of McKinleyville	6/25/2007	2:32:25	41.1155	-124.825	18	5	5	3.36E+23	128	84	160