Hmmm, checked with NEIC serach engine. For Mag:

"Setting the magnitude range is optional. To retrieve all earthquakes, including those without assigned magnitudes, leave these fields blank. The data base contains earthquakes with known magnitude values from 0.1 to 9.9. To restrict the data selection to a specific magnitude range, set the Minimum and Maximum Magnitude values to the appropriate limits. The Minimum Magnitude must be 1.0 or greater."

So maybe 1.0 to 9.9 might be a good starting point.

With regards to Intensity:

"Setting the intensity range is optional. To retrieve all intensities, set the Minimum and Maximum Intensity values to 0 or leave the fields blank. Intensity values range from 1 to 12. Most earthquakes do NOT have intensity values associated with them."

Wonder how usefull intensity is. Wadda ya think?

What about Depth, should we add that? Maybe a depth range as an option?

Type I've got Ml, Mb, Ms, Mw ... Any others anybody ?

M