Magnitude of completeness for the Northern stations of the Egyptian National Seismological Network
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S. I. SCJGE-1 2019
Magnitude of completeness for the Northern stations of the Egyptian National Seismological Network H. E. Abdel Hafiez 1 & Mostafa Toni 2 Received: 24 January 2020 / Accepted: 18 May 2020 # Saudi Society for Geosciences 2020
Abstract After the occurrence of an earthquake near Cairo on October 1992 (Mw 5.8), the Egyptian authorities established the Egyptian National Seismological Network (ENSN), which was targeted to monitor the seismic activity in and around Egypt. The ENSN started operation in 1997 with 66 stations installed by the National Research Institute of Astronomy and Geophysics (NRIAG). Almost 55,000 events were recorded up until 2018 since the time of ENSN’s operation. After more than 20 years of establishing ENSN, a scientific project was funded to review the detectability of the stations by different methods; so, the goal of this research is to evaluate the magnitude of completeness (Mc) which represents an important parameter for instrumental catalog studies using different catalog-based methods. The Mc is calculated based on deflection from the linear relation of frequency-magnitude of the recorded events in ENSN’s catalog. Calculation of Mc is indispensable for knowing and clarifying the seismicity parameters such as the b value in the Gutenberg-Richter equation. Three different methods were used, i.e., maximum curvature method (MAXC), b value stability approach (MBS), and entire magnitude range method (EMR). The results determine the variations among different methods, up to 0.5 magnitudes unit is observed. The importance of this study comes from its concentrate on the detectability of ENSN’s stations to show their efficiency for recording seismic events with high accuracy and for contributing in evaluation of seismic hazard in Egypt, in seismic engineering applications to mitigate earthquake risk, and in changing the position of bad recording stations to a quieter place with minimum noise level. Keywords Earthquake catalog . ENSN . Magnitude of completeness . Detectability of seismic networks
Introduction The magnitude of completeness (Mc) is an indispensable parameter for most of seismicity and seismic hazard studies. Theoretically, Mc is the smallest magnitude at which all of the earthquakes in a space-time volume are detected (Rydelek and Sacks 1989). In most earthquake catalogs, the Mc keeps changing with time usually decreasing due to establishment more seismographs and advancement in analysis. The seismic activity of Egypt is known to be moderate to small and obThis article is part of the Topical Collection on Current Advances in Geological Research of Egypt * Mostafa Toni [email protected] 1
National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo 11421, Egypt
2
Geology Department, Faculty of Science, Helwan University, Cairo, Egypt
served as a result of the relative movements between the African, Arabian, and Eurasian plates. The maximum earthquake activities are reported in the eastern portion of Egypt, i.e., the Gulf of Aqab
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