Brian,

I was thinking Long Beach was a larger quake for some reason. Northridge takes the cake, with 12 5+ aftershocks. I did a circular (100 km) from the PDE and California CDMG catalogs and found this;

U. S. G E O L O G I C A L S U R V E Y
E A R T H Q U A K E D A T A B A S E

FILE CREATED: Sun Aug 26 08:27:43 2007
Circle Search Earthquakes= 41
Circle Center Point Latitude: 34.000N Longitude: 118.000W
Radius: 100.000 km
Catalog Used: CDMG
Magnitude Range: 5.0 - 10.0
Data Selection: California (CDMG)

CAT YEAR MO DA ORIG TIME LAT LONG DEP MAGNITUDE IEFM DTSVNWG DIST
NFPO km
TFS

CDMG 1812 12 08 15 33.70 -117.90 6.90 UKDMG 7... ....... 34
CDMG 1827 09 24 04 34.00 -119.00 5.50 UKDMG 6... ....... 92
CDMG 1889 08 28 0215 34.10 -117.90 5.20 UKDMG 6... ....... 14
CDMG 1893 04 04 1940 34.30 -118.60 5.40 UKDMG 8... ....... 64
CDMG 1894 07 30 0512 34.30 -117.60 5.90 UKDMG 6... ....... 49
CDMG 1899 07 22 0046 34.20 -117.40 5.50 UKDMG 7... ....... 59
CDMG 1899 07 22 2032 34.30 -117.50 6.50 UKDMG 8... ....... 56
CDMG 1899 12 25 1225 33.80 -117.00 6.60 UKDMG 9... ....... 95
CDMG 1907 09 20 0154 34.20 -117.10 6.00 MLRI 7... ....... 85
CDMG 1910 04 11 0757 33.70 -117.40 5.00 UKTO .F.. ....... 64
CDMG 1910 05 13 0620 33.70 -117.40 5.00 UKTO 5... ....... 64
CDMG 1910 05 15 1547 33.70 -117.40 6.00 MLRI 7... ....... 64
CDMG 1918 04 21 223225 33.75 -117.00 6.80 MLGR 9D.. ....... 96
CDMG 1918 06 06 2232 33.75 -117.00 5.00 UKTO 5... ....... 96
CDMG 1923 07 23 073026 34.00 -117.25 6.25 MLGR 7... ....... 69
CDMG 1927 08 04 1224 34.00 -118.50 5.00 UKTO 6... ....... 46
CDMG 1930 08 31 004036 33.95 -118.63 5.20 MLEH 7... ....... 58
CDMG 1933 03 11 015407.80 33.62 -117.97 6.30 MLPAS 9D.. ....... 42
CDMG 1933 03 11 0209 33.75 -118.08 5.00 MLPAS .... ....... 28
CDMG 1933 03 11 0230 33.75 -118.08 5.10 MLPAS .... ....... 28
CDMG 1933 03 11 0323 33.75 -118.08 5.00 MLPAS .... ....... 28
CDMG 1933 03 11 051022 33.70 -118.07 5.10 MLPAS .... ....... 33
CDMG 1933 03 11 051804 33.58 -117.98 5.20 MLPAS .... ....... 47
CDMG 1933 03 11 065803 33.68 -118.05 5.50 MLPAS .... ....... 35
CDMG 1933 03 11 085457 33.70 -118.07 5.10 MLPAS .... ....... 33
CDMG 1933 03 11 0910 33.75 -118.08 5.10 MLPAS .... ....... 28
CDMG 1933 03 11 1425 33.85 -118.27 5.00 MLPAS .... ....... 29
CDMG 1933 03 13 131828 33.75 -118.08 5.30 MLPAS 4... ....... 28
CDMG 1933 03 14 190150 33.62 -118.02 5.10 MLPAS .... ....... 42
CDMG 1933 10 02 091017.60 33.78 -118.13 5.40 MLPAS 6... ....... 27
CDMG 1938 05 31 083455.40 33.70 -117.51 10 5.50 MLPAS 6... ....... 56
CDMG 1941 11 14 084136.30 33.78 -118.25 5.40 MLPAS 8D.. ....... 33
CDMG 1943 08 29 034513 34.27 -116.97 5.50 MLPAS 6... ....... 99
CDMG 1952 08 23 100907.10 34.52 -118.20 13 5.00 MLPAS 6... ....... 60
CDMG 1970 09 12 143053 34.27 -117.54 8 5.40 MLPAS 7... ....... 51
CDMG 1971 02 09 140041.80 34.41 -118.40 8 6.40 MLPAS ED.. ....... 58
CDMG 1971 02 09 140108 34.41 -118.40 8 5.80 MLPAS .... ....... 58
CDMG 1971 02 09 140244 34.41 -118.40 8 5.80 MLPAS .... ....... 58
CDMG 1971 02 09 141028 34.41 -118.40 8 5.30 MLPAS 5... ....... 58
CDMG 1971 02 09 144346.70 34.31 -118.45 6 5.20 MLPAS .F.. ....... 53
CDMG 1973 02 21 144557.30 34.06 -119.04 8 5.90 MLPAS 7D.. ....... 95

U. S. G E O L O G I C A L S U R V E Y
E A R T H Q U A K E D A T A B A S E

FILE CREATED: Sun Aug 26 08:29:45 2007
Circle Search Earthquakes= 24
Circle Center Point Latitude: 34.000N Longitude: 118.000W
Radius: 100.000 km
Catalog Used: PDE
Magnitude Range: 5.0 - 10.0
Data Selection: Historical & Preliminary Data

CAT YEAR MO DA ORIG TIME LAT LONG DEP MAGNITUDE IEFM DTSVNWG DIST
NFPO km
TFS

PDE 1973 02 21 144557.30 34.06 -119.04 8 5.90 MLPAS 7C . ....... 95
PDE 1979 01 01 231438.90 33.95 -118.68 11 5.10 mb GS 6D . ....... 63
PDE 1987 10 01 144220 34.06 -118.08 10 6.10 MLBRK 8CFM ....... 9
PDE 1987 10 04 105938.10 34.07 -118.10 8 5.60 MLBRK .C M ....... 12
PDE 1988 11 20 053928.60 33.51 -118.07 6 5.00 mb GS 5F . ....... 54
PDE 1988 12 03 113826.40 34.15 -118.13 13 5.00 MLBRK 6C . ....... 20
PDE 1989 01 19 065328.80 33.92 -118.63 12 5.20 mb GS 6C . ....... 58
PDE 1989 04 07 200730.20 33.62 -117.90 13 5.00 mb GS 6D . ....... 43
PDE 1990 02 28 234336.60 34.14 -117.70 5 6.20 MLBRK 7C M ....... 31
PDE 1991 06 28 144354.50 34.26 -118.00 11 5.80 mb GS 7CFM ......S 29
PDE 1994 01 17 123055.39 34.21 -118.54 18 6.80 Ms GS 9CFM U.....M 54
PDE 1994 01 17 123939.80 34.26 -118.53 14 5.00 MLGS .. . ....... 57
PDE 1994 01 17 155410.75 34.37 -118.62 12 5.00 MLBRK .F . ....... 70
PDE 1994 01 17 204602.39 34.30 -118.57 9 5.20 MLBRK .F . ....... 61
PDE 1994 01 17 233330.69 34.33 -118.70 9 5.90 Ms GS .DFM ....... 73
PDE 1994 01 18 004308.89 34.38 -118.70 11 5.50 MLBRK .. . ....... 76
PDE 1994 01 18 152346.89 34.38 -118.56 7 5.00 MLBRK .F . ....... 66
PDE 1994 01 19 210928.61 34.38 -118.71 14 5.50 MLBRK .F M ....... 77
PDE 1994 01 19 211144.90 34.38 -118.62 11 5.10 MLPAS .. . ....... 70
PDE 1994 01 29 112035.95 34.31 -118.58 1 5.40 MLBRK .D . ....... 63
PDE 1994 03 20 212012.26 34.23 -118.47 13 5.30 MwHRV 6D M ....... 50
PDE 1994 04 06 190104.06 34.19 -117.10 7 5.00 MLBRK 5F . ....... 86
PDE 1995 06 26 084028.94 34.39 -118.67 13 5.20 MLBRK 5F . ....... 75
PDE 1997 04 26 103730.67 34.37 -118.67 16 5.10 MLPAS 5F . ....... 74

Ofcourse we don't have a lot of data on the 1812 quake, other than it was very large. But I think I have read that was closer to Santa Barbara, or Ventura.

Glen