Discrepancies Between Prototype International Data Centre, International Seismological Centre & USGS Seismic Magnitudes

摘要

A discrepancy between body-wave magnitudes, from the Prototype International Data Centre (PIDC) and the U.S. Geological Survey (USGS), has persisted since 1995, and amounts to a few tenths of a magnitude unit. Since 1999 we have studied the discrepancy between magnitudes published by different agencies and this final report is comprised of two sections. The first, is a stand-alone paper (published in the 2002 November/December issue of the Seismological Society of America's Seismological Review Letters) comparing the PIDC magnitudes with values assigned by a method that as closely as possible reproduces the Veith-Clawson protocol for reporting seismic body wave magnitudes. That protocol is the most clearly specified, or many different body- wave magnitude scales. The second section here, is a report which documents in detail the actual discrepancies between magnitudes assigned by three key agencies - namely, the USGS, the PIDC, and the International Seismological Centre (ISC).