Development a local magnitude scale for South Egypt

A local magnitude (ML) scale for the southern Egypt region was developed using 3435 maximum amplitudes of 343 high-quality records of earthquakes recorded by the Egyptian National Seismic Network (ENSN). The analysis is started by the relocation of the recorded earthquakes, and then instrument responses were deconvolved from the recording and simulated on a standard Wood–Anderson torsion seismograph. Zero-to-peak amplitude of Sg or Lg waves in the two horizontal components is measured on each simulated Wood–Anderson seismograph. Events that were recorded by at least four stations and located at hypocentral distances between 10 and 1000 km and with a magnitude range of 1–4.5 are selected for preforming the analysis. The maximum recorded hypocentral depth was 40 km. The normalized amplitude decay shows two transition distances at 90 km, and 175 km yielding three segments. The trilinear regression model was adopted to retrieve three formulae that describe the local magnitude as follows: ML = log (A) + 1.4223*log(R) −0.0014*(R) +0.301 for R