A state-of-the-art seismic source model for the United Arab Emirates

Abstract

Despite the United Arab Emirates (UAE) is characterized by low to moderate local seismicity, the country is within close proximity to be affected by the surrounding seismically-active regions, mainly, the Zagros and the Makran regions. Appreciable ground shaking levels were felt in many parts of UAE during the past 15 years. A new seismic source model for UAE was specifically developed herein, as a first and significant step towards a critical re-evaluation of the seismic hazard in the UAE. Updated earthquake and focal mechanism catalogs have been incorporated in the definition and characterization of the seismic sources. This was done after unifying magnitudes, seismicity declustering, as well as performing completeness checks. Geological, tectonic, active faults, and crustal thickness information were considered in the delimitation of the source’s boundaries. The proposed seismic source model consists of a total of 12 area seismic sources, i.e., 10 shallow-depth (h ≤ 35 km) and 2 intermediate-depth zones (35 < h ≤ 70 km) spanning the potential seismic regions which may contribute to the UAE seismic hazard. This work is the first in which intermediate-depth seismicity is included in a zoning model for the region. Separate earthquake and focal mechanism sub-catalogs were generated after the delimitation of each defined seismic source. The seismicity occurrence parameters (b-value, annual rate of earthquakes above Mw 4.0, and the maximum possible magnitude) were computed individually for each source. A predominant stress regime was also assigned to each seismic source based on the inversion of the available focal-mechanism data.