An ML Scale in Tehran Seismic Network

Investigation of archived data between 1996 to August 2002 in Tehran seismic network shows that magnitude values in the database have not been determined using a single formulae or a specific method. Comparison of magnitude values in the database with those values that have been published in the ISC Bulletin shows that magnitude values in the Tehran network are underestimated. By using magnitude values in the database and corresponding mb ISC values, a local-magnitude scale as ML=log(v/4π)+2.5log(Δ)-1.8 is derived, where v is peak-to-peak amplitude in micrometer/second and Δ is epicentral distance in kilometers. Using this formula gives a better estimate for the magnitude of earthquakes in comparison with the formula that is presently used in the Tehran network.