New local magnitude scales for Egypt

Area of Science:

• Seismology
• Earthquake Engineering

Background:

• Accurate earthquake magnitude estimation is crucial for seismic hazard assessment.
• Existing local magnitude (M_L) scales may not fully represent the complex seismotectonic setting of Egypt.

Purpose of the Study:

• To develop and validate new local magnitude (M_L) scales tailored for Egypt.
• To improve the consistency and accuracy of earthquake magnitude determinations across different regions of Egypt.

Main Methods:

• Utilized a dataset of 14,453 Wood-Anderson amplitudes from 1670 earthquakes recorded by the Egyptian National Seismic Network (ENSN).
• Applied a trilinear geometrical scattering model and singular value decomposition to determine distance and station correction terms.
• Divided Egypt into four sub-tectonic regions (South, North, Red Sea, Mediterranean) to account for regional variations in attenuation.

Main Results:

• Developed new M_L scales for Egypt, incorporating regional attenuation characteristics with transition distances at 90 km and 175 km.
• Achieved unbiased M_L magnitude estimates over a wide distance range (10-1000 km).
• Demonstrated improved consistency in magnitude estimates from the ENSN network.

Conclusions:

• The newly derived M_L scales provide more reliable earthquake magnitude assessments for Egypt.
• These scales enhance the understanding of seismic wave propagation and attenuation within Egypt's diverse tectonic environments.
• The findings contribute to more accurate seismic hazard analysis and risk management in the region.