If the PDE has a larger magnitude of completeness, isn't that the catalog that we should be using? We all know that magnitudes get adjusted with time. I'm also noticing that the NOA, or National Observatory of Athens, data is all in Ml.

At any rate, I went an ran a comparison of the NOA and PDE for the first four months of 1990. During this comparison I noticed that the min/max coordinates were a little different then the rough set of coordinates that I previously had used. So adjusting the coordinates to what was on the NOA for the first 4 months I got a new set of data. Leaving just the M4 events from the NOA and matching up the PDE to the NOA events I find that 7 of the events reported as M4 on the NOA are less then M4 on the PDE. Overall the PDE had a total of 89 M4+ events and 7 M3+ events while the NOA had 65 M4+ events. There were some differences in location and depth which are understandable. For example:

On the NOA: 1990 JAN 13 05 05 58.3 36.20 27.15 2 4.7
On the PDE: 1990 01 13 050559.47 36.11 27.19 43 4.70 MDATH .... .......

PDE depth was 43 while NOA depth was 2 which will cause the coordinates to be slightly off. The time is also off by about a second but that is also understandable depending on what recording stations were used when compiling this data.

Anyway, using the new set of coordinates, I get the following results for M4 events:

FILE CREATED: Mon Jun 5 18:00:55 2000
Geographic Grid Search Earthquakes= 1591
Latitude: 42.000N - 34.000N
Longitude: 27.500E - 19.500E
Catalog Used: PDE
Date Range: Year: 1990 - 1999 Month: 01/Day: 01 Month: 12/Day: 31
Magnitude Range: 4.0 - 5.0

So Greece gets an M4 every 2.29 days instead of every day.

If I had used the NOA, the number would be less.

Dennis