USGS Homepage

Back to the Deformation and Stress-Change main page

Online Southern California earthquake catalog

Clickable map of the events

R. S. Stein and T. C. Hanks,
M > 6 Earthquakes in Southern California during the Twentieth Century: No Evidence for a Seismicity or Moment Deficit, Bull. Seismol. Soc. Amer., 88, pp. 635-652, 1998.
[Online article] [Clickable map and Catalog of earthquakes in Southern California] [Reviews of this paper Nature, Science and Science News Online]

Southern California Earthquake Catalog

Table 1. 1903-1997 M>6.0 Southern California Catalog (32°00'-36°15'N/114°00'-122°00'W)
Locality 
Yr
Mo
Dy 
Latitude 
Longitude 
WGCEP 
Focal mechanism 
Mo
M
deg
min
deg 
min
zone
strike° 
dip° 
rake° 
1018Nm 
Imperial Valley  06 4 19 32 54 115 30 B - - - 2 6.2
Death Valley  08 11 4 36 ? 117 ? C - - - 1? 6 ?
Imperial Valley  15 6 23 32 48 115 30 B - - - 1 6.0
Volcano Lake (Baja)  15 11 21 32 0 115 0 C 312 88 179 9 6.6
San Jacinto  18 4 21 33 45 117 0 A 150 87 -176 15 6.8
Parkfield  22 3 10 36 0 120 30 B 327 90 180 1 6.0
San Bernardino  23 7 23 34 0 117 15 A 320 85 180 2 6.2
Santa Barbara  25 6 29 34 18 119 48 C - - - 20 6.8
Lompoc 27 11 4 34 36 120 54 C 315 42 94 50 7.1
Long Beach  33 3 11 33 42 118 0 B 315 80 -170  5 6.4
Parkfield  34 6 8 36 0 120 30 B 327 90 180 1 6.0
Laguna Salada (Baja)  34 12 30 32 15 115 30 B 311 91 80 6 6.5
Colorado River delta  34 12 31 32 0 114 45 B 317 89 180 40 7.0
Imperial Valley  40 5 19 32 48 115 30 B 325 90 180 30 7.0
Lower Borrego Valley  42 10 21 33 0 116 0 A 61 88 10 5 6.4
Salton Sea aftershock  42 10 22 33 12 115 42 B - - - 1 6.0
Walker Pass  46 3 15 35 42 118 6 C 346 45 -117  1 6.0
Manix 47 4 10 35 0  116 36 C 65 85 8 6 6.5
Desert Hot Springs  48 12 4 33 54 116 24 A 305 70 169 1 6.0
Kern County  52 7 21 35 0 119 0 B 73 75 50 110 7.3
Kern Co. aftershock  52 7 21 35 0 119 0 B - - - 3 6.3
Kern Co. aftershock  52 7 29 35 24 118 54 C 53 90 - 3 6.3
Bryson 52 11  22 35 42  121 12 C 305 63 175 1 6.0
Arroyo Salada  54 3 19 33 18 116 12 A 30 85 175 3 6.3
Parkfield  66 6 28 36 0 120 30 B 327 90 180 1 6.0
Borrego Mountain  68 4 9 33 11 116 8 A 312 83 180 10 6.6
San Fernando  71 2 9 34 25 118 24 B 293 52 72 10 6.6
Imperial Valley  79 10 15 32 38 115 19 B 326 90 180 6 6.5
Victoria (Baja)  80 6 9 32 13 114 59 B 140 90 180 5 6.4
Coalinga  83 5 2 36 14 120 19 C 127 23 90 5 6.4
Kettleman Hills  85 8 4 36 7 120 9 C 142 12 109 2 6.2
North Palm Springs  86 7 8 34 0 116 37 A 283 41 147 1 6.0
Whittier Narrows  87 10 1 34 4 118 5 A 280 40 98 1 6.0
Elmore Ranch  87 11 24 33 5 115 48 A 217 79 4 2 6.2
Superstition Hills  87 11 24 33 1 115 51 A 303 89 -180 10 6.6
Joshua Tree  92 4 23 33 58 116 18 C 171 89 -177 2 6.2
Landers  92 6 28 34 12 116 26 C 341 70 -172 110 7.3
Big Bear  92 6 28 34 10 116 49 C 321 86 200 5 6.5
Northridge  94 1 17 34 13 118 32 B 122 40 101 13 6.7
Northridge aftershock  94 1 17 34 20 118 41 B 116 46 89 1 6.0

References can be found in the Appendix. Earthquakes are mapped in Figs. 1 and 2; WGCEP seismotectonic zones are shown in Fig. 2. Unknown focal mechanisms are blank. You can consult the Appendix below


Table 2. What's Not in Table 1
Year Mo Dy  Locality  Lat.(°)  Lon.(°)  M>6  Ref. M<6  Ref.
1907 09 20  San Bernardino  34.2? 117.1? 6  R 5.3  HHT
5.3 TP
1910 05 15  Elsinore  33.7? 117.4 6  R 5.3  HHT
5 1/2  TP
1915 06 23  Imperial Valley (0456)  32.8 115.5 6 1/4  R 5.5  HHT
5.9 TP
1916 10 23  Gorman  34.9 118.9 6  R 5.3  HHT
5.3 TP
1916 11 10  Death Valley area  35.3? 116.7 6.1  E <6  R
5.9 GJ
1935 02 24  Laguna Salada (Baja)  32.0 115.2 6  R < 6  HHT
1937 03 25  Southeast Anza  33.5 116.4 6  R 5.6  HHT
5.6 D
1952 07 23  Kern Co. aftershock  35.4 118.6 6.1  R 5.7  TH
 
Year Mo Dy  Locality  Lat.(°)  Lon.(°)  Mo (1020 Nm) 
M 
Ref.
1857 01 09  Fort Tejon  35.7 120.3 8  7.9 S, GS
1872 03 26  Owens Valley  36.7 118.1 2  7.4 BC
1892 02 24  Laguna Salada  32.5 116.6 1  7.3 S, MR

The first section lists M<6 earthquakes and the second lists M>7 shocks occuring during 1850-1900 within Fig. 1. References: R (Richter, 1958), HHT (Hanks et al., 1975), TP (Toppozada and Parke, 1982), E (Ellsworth, 1990), GJ (Gross and Jaume, 1995), TH (Thatcher and Hanks, 1973), D (Doser, 1990), S (Sieh, 1978), GS (Grant and Sieh, 1994), BC (Beanland and Clark, 1994), S (Strand, 1980), MR (Mueller and Rockwell, 1995). Also see Appendix below.


Table 3. Frequency-Magnitude Relationships for the M>6.0 Southern California Catalog
Seismotectonic 
Zone 
n 
Min. Magnitude 
of completeness 
by Maximum Likelihood 
by Least Squares 
b 
a 
b 
a 
All 
40 
6.0 
0.97±0.15 
5.45 
1.04±0.04 
5.89 
All 
42 
6.0 º 
1.01±0.16 
5.73 
1.04±0.04 
5.93 
All 
28 
6.2 
1.04±0.20 
5.91 
1.11±0.04 
6.38 
A 
10 
6.0 
1.21±0.38 
6.26 
1.25±0.14 
6.56 
B 
17 
6.0 
0.95±0.23 
4.97 
0.97±0.07 
5.10 
C 
13 
6.0 
0.86±0.24 
4.31 
0.87±0.04 
4.41 
n is the number of earthquakes in each set. a is in units of yr-1. º Assumes the 1903-1997 catalog is missing two M=6.0 earthquakes.



APPENDIX

This appendix provides a brief discussion and references for the locations, seismic moments, and focal mechanisms of the earthquakes given in Tables 1 and 2 and Fig. 1. Unless otherwise specified, locations and seismic moments are those given by Hanks et al (1975), with conversion from Mo to M following Hanks and Kanamori (1979).

1857 Fort Tejon. We use revised surface slip measurements (Grant and Sieh, 1993; Salyards et al., 1992; Sieh, 1978; Sieh and Jahns, 1984), and a rupture width (the down-dip dimension) equal to the local depth of contemporary microseismicity along the fault from Hill et al (1990). Microearthquakes extend to 12 km depth south of Parkfield, 15-20 km in the Carrizo Plain, 18-25 km at Tejon Pass, 12-15 km along the Mojave segment, and 17 km at Cajon Pass. For a shear modulus of 3.0 x 1010 Nm-2, this yields a moment of 7.7 x 1020 Nm (M=7.9). Deng and Sykes (1997) used 9.0 x 1020 Nm (M=7.9); Ellsworth (1990) assigned the earthquake M=7.8 (5.6 x 1020 Nm), which was adopted by WGCEP (1995).

1872 Owens Valley. Our location, focal mechanism, Mo and M estimates use the surface slip observations (Beanland and Clark, 1994), a fault width of 12.5 km, a dip of 80°E, and a shear modulus of 3.0x1010 Nm-2.

1892 Laguna Salada. Strand (1980) seems to have been the first to recognize the location of this event in the Laguna Salada, ~30 km south of the International Border at the longitude of El Centro. Earlier references customarily place this event on the Aqua Blanca fault, ~100 km to the south. Location and focal mechanism from Mueller and Rockwell (1995). Strand gives Mo=200 x 1018 Nm from AVI. Mueller and Rockwell give a minimum Mo of 42 x 1018 Nm, based on surface offsets. We use 100 x 1018 Nm.

1906 Imperial Valley. Considerable uncertainty still attends the location (Toppozada and Parke, 1982) and magnitude of this event. M is assigned from the Ms = 6.2 of Ellsworth (1990).

1907 San Bernardino. M < 6 assignment (Hanks et al., 1975; Toppozada and Parke, 1982).

1908 Death Valley. Location and magnitude very uncertain. M = 6? from Ellsworth (1990).

1910 Elsinore. M<6 assignment (Hanks et al., 1975; Toppozada and Parke, 1982).
 

1915 Imperial Valley (150623). Two earthquakes occurred on June 23, the first at 0359 and the second at 0456. Richter (1958) assigned M = 6 1/4 to each of them, but both Hanks et al (1975) and Toppozada and Parke (1982) find both of them to be M < 6 on the basis of AVI. Here we assign M = 6 to the first event and M < 6 to the second event, as did Ellsworth (1990). Put another way, we consider the strain release of both events to be the equivalent of one M = 6 event.

1915 Colorado River Delta (151121). Location, focal mechanism and moment from Doser (1994).

1916 Gorman (161023). M < 6 assignment (Hanks et al., 1975; Toppozada and Parke, 1982).

1916 Death Valley Region (161110). The location (Gross and Jaume, 1995). Richter (1958) did not list this event as M > 6, although Ellsworth (1990) did. Gross and Jaumé (1995) find M = 5.9, principally because their new location is ~100 km closer to the seismic stations at Reno, Mount Hamilton, and Berkeley.

1918 San Jacinto. Hanks et al (1975) estimated Mo = 15 x 1018 Nm. Doser (1992) found Mo = 14 ± 5 x 1018 Nm from teleseismic body waves. Focal mechanism (Doser, 1992).

1922 Parkfield. Bakun and McEvilly (1984) assign the 1922, 1934, and 1966 Parkfield earthquakes are nearly identical. We assign them the same location, and same focal mechanism and Mo (Tsai and Aki, 1969).

1923 San Bernardino Area. Hanks et al (1975) estimate Mo = 1 x 1018 Nm. Doser (1992) finds Mo = 2 to 3 x 1018 Nm from a single teleseismic recording. In Table 1, we give Mo = 2 x 1018 Nm and M=6.2. Focal mechanism (Doser, 1992).

1927 Lompoc, offshore. Both the location and size of this earthquake have been sources of considerable controversy. The location of this event is that of Hanks (1979), but interested readers may wish to peruse these references: (Gawthrop, 1978; Gawthrop, 1981; Hanks, 1981). Mo estimates for this earthquake vary by an order of magnitude. In units of 1018 Nm and in chronological order, these estimates are 100 (Hanks et al., 1975), 65 (Yeh, 1975), 10 (Helmberger et al., 1992), and 30 (Satake and Somerville, 1992). Our "consensus" Mo is 50 x 1018 Nm and M = 7.1. Focal mechanism (Yeh, 1975).

1933 Long Beach. Location, focal mechanism, and Mo (Hauksson and Gross, 1991).

1934 Parkfield (340608). Location (Bakun and McEvilly, 1984). Focal mechanism and Mo (Tsai and Aki, 1969). See 1922 Parkfield above.

1934 Colorado River Delta (341230). Location, focal mechanism and moment from Doser (1994).

1934 Colorado River Delta (341231). Location, focal mechanism and moment from Doser (1994).

1937 Anza, southeast. Location (Sanders et al., 1986). M~6 assignment Hanks et al (Doser, 1990b; 1975).

1940 Imperial Valley. Location (Doser and Kanamori, 1986). Hanks et al (1975) give Mo = 30 x 1018 Nm; Doser (1990b) give 23 ± 4 x 1018 Nm, and King and Thatcher (1997) find 32±3 x 1018 Nm from geodetic inversion; we use 30 x 1018 Nm. Focal mechanism (Doser, 1990b).

1942 Lower Borrego Valley (421021). Location (Hanks and Allen, 1989) based on the earlier determinations (Doser and Kanamori, 1986; Hanks et al., 1975; Sanders et al., 1986), exactly that given by Richter (1958). We use Mo = 5 x 1018 Nm, based on the estimates of 9 x 1018 Nm (Hanks et al., 1975), 1.5 ± 0.5 x 1018 Nm (Doser, 1990b) and 3.3 x 1018 Nm (Bent and Helmberger, 1991). Focal mechanism (Doser, 1990b).

1942 Salton Sea aftershock (421022). This event is nominally an aftershock of the significantly larger lower Borrego Valley earthquake, which occurred 7.5 hours earlier, but it occurred far to the northeast, beneath the Salton Sea. Perhaps it possesses a relationship to the Lower Borrego Valley earthquake that is similar to that between the 1987 Elmore Ranch and Superstition Hills earthquake (Hanks and Allen, 1989). This event is a marginal entry in Table 1, with ML=5.5 (Hileman et al., 1973), but Bent et al (1991) have determined Mo = 1.5 x 1018 Nm. We list 1 x 1018 Nm, M = 6, here. Location (Doser and Kanamori, 1986; Hileman et al., 1973).

1946 Walker Pass. Location (Richter, 1958). Mo (Hanks et al, 1975). The focal mechanism is for a more recent event to which the 1946 earthquake seems to conform (Dollar and Helmberger, 1985). The mater event location is 35°45'N, 118°03'W.

1947 Manix. Location, focal mechanism, and Mo (Doser, 1990a).

1948 Desert Hot Springs. Location, focal mechanism, and Mo (Nicholson, 1996).

1952 Kern County, mainshock (520721). Location, Mo and focal mechanism (Stein and Thatcher, 1981).

1952 Kern County, aftershock (520721). This event (Table 2) occurred on July 23, 1952. According to Thatcher and Hanks (1973), Mo = 0.4 x 1018 Nm for this event and M<6.

1952 Kern County, aftershock (520729). Location and focal mechanism (Bath and Richter, 1958).

1952 Bryson (521122). Location and focal mechanism (Dehlinger and Bolt, 1987). Magnitude (Ellsworth, 1990).

1954 Arroyo Salada. Location (Richter, 1958; Sanders et al., 1986). Focal mechanism (Doser, 1990b). Mo = 3 x 1018 Nm (Hanks et al., 1975), 2.4 ± 0.3 x 1018 Nm (Doser, 1990b), 1.9 x 1018 Nm (Bent and Helmberger, 1991).

1966 Parkfield (660628). Location (Bakun and McEvilly, 1984). Focal mechanism and Mo (Tsai and Aki, 1969).

1966 El Golfo, Baja California, Mexico (660807). Location, Mo, focal mechanism (Ebel et al., 1978).

1968 Borrego Mountain. Location and focal mechanism (Allen and Nordquist, 1972). Mo (Burdick and Mellman, 1976; Hanks and Wyss, 1972).

1971 San Fernando. Location and focal mechanism (Whitcomb et al., 1973).

1979 Imperial Valley. Location and focal mechanism (Chavez et al., 1982). Mo (Kanamori and Regan, 1982).

1980 Victoria, Baja California (Mexico). Location, Mo, and focal mechanism (Nakanishi and Kanamori, 1984).

1983 Coalinga. Location and focal mechanism (Eaton, 1990). Mo (Sipkin and Needham, 1990).

1985 Kettleman Hills. Location, focal mechanism, and Mo (Ekström et al., 1992).

1986 North Palm Springs. Location (Jones et al., 1986). Focal mechanism and Mo (Pacheco and Nábelek, 1988). Hartzell (1989) finds Mo to be 1.6 to 1.8 x 1018 Nm. We prefer M=6, given that ML = 5.9 (Jones et al., 1986).

1987 Whittier Narrows (871001). Location (Hauksson and Jones, 1989). Focal mechanism (Bent and Helmberger, 1989). Mo (Bent and Helmberger, 1989; Bolt et al., 1989).

1987 Elmore Ranch (871124). Location (Magistrale et al., 1989). Focal mechanism and Mo (Sipkin, 1989; Bent et al, 1989).

1987 Superstition Hills (871124). Location [Magistrale, 1989 #536]. Focal mechanism and Mo (Sipkin, 1989; Bent et al, 1989).

1992 Joshua Tree (920423). Location [Hauksson, 1993 #533]. Focal mechanism and Mo (Velasco et al., 1994).

1992 Landers (920628). Location (Hauksson et al., 1993). Focal mechanism and Mo (Velasco et al., 1994; Wald and Heaton, 1994).

1992 Big Bear (920628). Location (Hauksson et al., 1993). Focal mechanism and Mo (Jones et al., 1993).

1994 Northridge (940117). Location (Hauksson et al., 1995). Focal mechanism and Mo (Wald et al., 1996).

1994 Northridge aftershock (940117). Location, focal mechanism and Mo (Dreger, 1997).