I have spent quite a bit of time recently working a on an automatic earthquake locating program. When I say locating, I really mean calculating the distance and direction from a quake to a specific location.

It works similar to the one used by the USGS on their map pages (i.e. 8 mi W of Ludlow, CA).

The reason I am re-inventing the wheel is because it's not available when accessing historical earthquake data catalogs. The one exception is the SCSN catalog using their "simpson map" function. But this is limited to Southern California only.

My program is now complete and it is surprisingly accurate. This is kind of surprising to me because I am no math expert and I am not an experienced database programmer. All of the calculations and formulas I used I made up myself.

If you are familiar with my web site (blog) you will know why I have created this. All locations for quakes above 4.0 had to be calculated manually. This usually takes a bit of time. My new program can now calculate 500 earthquakes (against 739 predefined locations), in just under 5 seconds.

The program was built using Access2000 with VBA. It needs a little more fine tuning, but if anyone is interested, I would be interested in figuring out a way to share the program.

Here is a sample... The first list is directly from the SCSN catalog, the second list is the output from my program based on the coordinates from the first list.

SCSN
12/2/2002 1:19:36 PM 3.29 3 SE Bombay Beach, CA
12/3/2002 2:59:21 AM 3.02 5 N Banning, CA
12/10/2002 9:04:01 PM 4.84 35 SSW Calexico, CA
12/10/2002 9:47:15 PM 3.97 35 SSW Calexico, CA
12/11/2002 3:20:38 PM 3.17 14 S Port Hueneme, CA
12/12/2002 2:47:04 AM 3.31 35 SSW Calexico, CA
12/12/2002 9:03:43 PM 4.21 27 SE Calexico, CA
12/22/2002 12:55:33 PM 3.48 12 NNW Indio, CA
12/27/2002 12:01:48 PM 3.17 36 SSE Calexico, CA
12/29/2002 7:36:07 PM 3.15 12 NE Arvin, CA

BRAD
12/2/2002 1:19:36 PM 3.29 2 SE Bombay Beach, CA
12/3/2002 2:59:21 AM 3.02 5 N Banning, CA
12/10/2002 9:04:01 PM 4.84 35 SSW Calexico, CA
12/10/2002 9:47:15 PM 3.97 35 SSW Calexico, CA
12/11/2002 3:20:38 PM 3.17 17 S Oxnard, CA
12/12/2002 2:47:04 AM 3.31 35 SSW Calexico, CA
12/12/2002 9:03:43 PM 4.21 28 SE Calexico, CA
12/22/2002 12:55:33 PM 3.48 12 N Indio, CA
12/27/2002 12:01:48 PM 3.17 36 SSE Calexico, CA
12/29/2002 7:36:07 PM 3.15 17 NW Tehachapi, CA