SPECIAL REPORT: Fontana, CA

Late in the evening of September 6, 2005 we have seen a small swarm of earthquakes developing around the Fontana area.

1.3 2005/09/06 11:52 PM ( 2 mi) NW of Loma Linda, CA
1.0 2005/09/06 11:03 PM ( 4 mi) NNE of Fontana, CA
1.2 2005/09/06 10:56 PM ( 4 mi) NNW of Rialto, CA
1.2 2005/09/06 10:20 PM ( 2 mi) WSW of Loma Linda, CA
2.0 2005/09/06 10:09 PM ( 4 mi) NNE of Fontana, CA
1.0 2005/09/06 10:08 PM ( 4 mi) NW of Rialto, CA
1.2 2005/09/06 9:53 PM ( 4 mi) NW of Rialto, CA
1.4 2005/09/06 9:39 PM ( 4 mi) NNE of Fontana, CA

Do these small quakes mean a larger one is on the way? I did some research and I will present my findings and let you decide for yourself whether these are foreshocks are just another small swarm.

I searched past earthquakes which have occurred within 10km of this current activity.

Since 1950 there have been 17 earthquakes of 3.5 or greater. Seven of these had at least one foreshock.

Here is a map showing the specific location we are talking about. Quakes shown on the map come from the list below:


Mainshocks are listed in BOLD

3.9 5/15/1955 5:03 PM

4.1 6/28/1960 8:00 PM

3.8 8/21/1960 11:07 PM

3.7 2/25/1965 11:21 AM

3.7 9/2/1966 11:06 AM

3.6 10/14/1967 12:36 AM

3.5 3/17/1975 12:13 AM

1.9 1/7/1983 5:01 PM
2.7 1/8/1983 6:29 AM
4.0 1/8/1983 7:19 AM

1.6 2/18/1987 12:52 AM
1.4 2/18/1987 4:03 AM
1.7 2/21/1987 5:19 AM
4.0 2/21/1987 11:15 PM

1.2 10/11/1997 2:26 AM
1.5 10/11/1997 11:16 AM
1.1 10/13/1997 11:51 AM
3.9 10/14/1997 10:31 PM

1.4 11/1/1997 11:32 AM
3.6 11/4/1997 2:36 PM

0.9 1/29/1999 2:53 AM
3.6 1/30/1999 11:24 PM

3.5 4/9/2000 6:52 AM

3.7 7/25/2002 12:43 AM

1.4 7/26/2004 6:32 AM
3.8 7/28/2004 8:19 PM

1.6 1/2/2005 12:19 PM
1.4 1/2/2005 8:34 PM
1.1 1/2/2005 9:51 PM
1.1 1/2/2005 10:01 PM
1.5 1/2/2005 10:53 PM
2.7 1/4/2005 8:21 AM
1.6 1/4/2005 8:21 AM
1.8 1/4/2005 8:49 AM
3.1 1/4/2005 8:49 AM
1.1 1/4/2005 9:31 AM
1.3 1/4/2005 8:25 PM
1.6 1/5/2005 2:12 PM
1.6 1/5/2005 2:26 PM
2.5 1/6/2005 12:11 PM
3.6 1/6/2005 12:11 PM
2.5 1/6/2005 12:32 PM
3.3 1/6/2005 2:22 PM
4.4 1/6/2005 2:35 PM