Readme for Catalog "cdmg2000"

1.	This catalog is an update from the CDMG 1996 catalog (Petersen et al., 1996).
The updating was done in two steps.  The first step was to extend the 1996 catalog, 
which went to 1994, to 2000.  To do the extension, we used the 1994 to 2000 catalog 
for northern California from Dr. Oppenheimer of USGS and the catalog for southern 
California from Drs. Kagan, Jackson, and Rong of UCLA.  The catalog for northern 
California is from a merge of the USGS and UC Berkeley catalogs.  The catalog for 
southern California is from a merge of the CIT and other catalogs.  We then merged 
the above two catalogs for northern and southern California to get an extended 
catalog, which goes to 2000.  The second step was to merge the extended catalog with 
the recently published catalog for magnitude equal to and greater than 5.5 by 
Toppozada, Branum, Petersen, Hallstrom, Cramer, and Reichle (CDMG map sheet 
49, 2000).  (This catalog has been updated by Toppozada and Branum (IASPEI, 
2002, in press) and by Toppozada et al. (2002, submitted to BSSA)).  This merge 
added about 50 pre-1932 events of M to the catalog. 

2.	One column in the catalog is for the source institutions.  In the above updating 
process, we have used the names of the institutions, such as USGS and UCLA, who 
did the merging for northern and southern California before our merging for the 
whole of California.  The source institutions that should be credited are to be found in 
the USGS and UCLA catalogs that we used.  For many large historical events this 
source column has been listed as CDMG because we used the information from 
Toppozada et al. (1978, 1981, 2000, 2002) who in turn credited the proper institutions 
or persons.

3.	For some early events the occurrence dates are available but not the hours and 
minutes and seconds.  In the 1996 catalog, 0.00 was placed at those locations for 
hours, minutes, or seconds to indicate that the number was not available.  When 
updated by Toppozada et al.'s recent work, we have used a number 99 to indicate that 
time is not available.  On the other hand, 0.00 is still a possible minute or second but 
not 99.

4.	We found that there was a rounding problem for the last digits of the latitude and 
longitude when the USGS catalog was reformatted and merged into the 1996 catalog.  
This has been corrected.

5.	The cut-off magnitude for this catalog is 4.0.  The completeness at M~4 or greater is 
after 1932 for southern California and after 1942 for northern California.  The catalog 
extends ~100 km beyond the state borders to include M  events in neighboring 
states or offshore that could cause damage in California.  The magnitudes for M 6 or 
larger are moment magnitude.

(12/21/01)