Rate of seismic deformation in the Gulf of Aqaba inferred from moment-tensor summation
- PDF / 648,561 Bytes
- 16 Pages / 475.945 x 680.426 pts Page_size
- 10 Downloads / 167 Views
ABSTRACT This study aims to quantify the rate of coseismic deformation in the Gulf of Aqaba. Earthquake catalogue, Gutenberg-Richter relationship and fault plane solutions were integrated to measure the size and shape of deformation using the moment-tensor summation technique. First, the Gutenberg-Richter relationship was established using seismicity data from the period of 19642019. Then, the moment-tensor summation based on 44 focal mechanism solutions was used to calculate the shape of deformation. The eigenvalues of moment-tensor reflect the diversity of focal mechanism solutions that alternate from normal to strike-slip fault styles in the deformation zone. The analysis reveals a dominant shear deformation in the Gulf of Aqaba that extends in a direction of N42.2E at a rate of 2.6 ± 0.04 mm yr1 and shortens in the direction of N305.2E at a rate of 2.0 ± 0.02 mm yr1. These results suggest that the active deformation occurring in the Gulf of Aqaba is due to the relative tectonic movements between the Arabian and African plates, as well as Sinai subplate. K e y w o r d s : focal mechanism, Gulf of Aqaba, Gutenberg-Richter law, moment magnitude, crustal deformation
1. INTRODUCTION The Dead Sea fault is one of the transform plate boundaries in the world, formed by the relative tectonic movements of the African and Arabian plates, as well as the key role of Sinai subplate. The Gulf of Aqaba represents a transition zone that connects the Dead Sea fault with a sinistral offset and the Red Sea rifting (Garfunkel, 1981; Salamon et al., 1996). The Gulf of Aqaba is formed by three structural basins that are typically bounded to the east and west by longitudinal faults (Ben-Avraham, 1985). The main fault is characterized at several locations by left-handed stepovers that continue as parallel faults with sinistral displacement, generating pull-apart basins (Daggett et al., 1986). The longitudinal basins and the en-echelon faults are shown later. Previous studies have used various datasets to indicate that this movement initiated during the late Miocene at ~1411 Ma (Garfunkel, 1981). The slip rate based on geodetic estimates indicates leftlateral deformation at 4.4 0.3 mm yr1 along the Gulf of Aqaba-Dead Sea transform
Stud. Geophys. Geod., 64 (2020), DOI: 10.1007/s11200-020-1028-7, in print © 2020 Inst. Geophys. CAS, Prague
i
S. Almadani
fault (Mahmoud et al., 2005), whereas the sinistral motion of 5.6 10 mm yr1 was determined for the southernmost segment of the Aqaba fault (McClusky et al., 2003). The low recurrence rate of earthquakes with magnitudes greater than six implies that the total horizontal slip rate of 24 mm yr1 is accommodated to the north of the western side of the Gulf of Aqaba (Makovsky et al., 2008). A kinematic study by Jestin et al. (1994) indicated that tectonic processes produced a seismogenic zone characterized by extensional-to-shear deformation, which revealed that seismicity in the Gulf is due to relative plate motion between the African and Arabian plates. This relative plate mo
Data Loading...
