Rupture Process Characteristics of August 1993 Aqaba Earthquake Sequence
Ali Kamel Abdel Fattah;
Abstract
This study is focused on the earthquake source process for the Gulf of Aqaba mainshock 1993 by examining its aftershock characteristics such as relocation, focal mechanisms, variation of their source parameters and their scaling source parameters. The purpose of this study concerns to investigate the characteristics of the mainshock rupture initiation, propagation and termination in relation to the aftershock characteristics.
The hypocenters relocated using P- and S- wave arrival times at several Egyptian seismic stations in addition to some collected arrivals of the Israeli, Jordanian and Saudi Arabia bulletins. The epicentral distribution of aftershocks concentrates as a cluster around a small area between
28.5°N-28.7°N and 34.5°E-34.7°E. The area of aftershock concentrations is considered to be a high stress accumulation patch. This patch may be interpreted in terms of asperity or barrier.
The focal mechanisms of the mainshock and five events of its aftershocks were derived from the stereographic projection using polarity readings of P- wave first motions of local, regional and teleseismic stations. The present focal mechanisms represent normal faulting mechanisms with minor left lateral strike slip component. For most of the events, the nodal planes selected as the fault imply high similarity in strike and dip. They are related to a local striking NW- SE fault trend and dipping to the SW. The selected fault planes are in a good agreement with the aftershock distribution. The observation of similar striking aftershock fault plane solutions over the entire fault plane can be explained by the inhomogeneous source model.
Most of the relocated events which represent large stress drops in this sequence are clustered around the small area of the aftershock distribution. This clustering of aftershocks with large stress drops with respect to the mainshock marks an apparent stress concentration, possibly associated with the arrest of the main shock rupture propagation by a fracture barrier. Also, the geographic stress drop distribution of aftershocks shows another one of high stress released area located close to the location of the Gulf of Aqaba mainshock 1995.
The hypocenters relocated using P- and S- wave arrival times at several Egyptian seismic stations in addition to some collected arrivals of the Israeli, Jordanian and Saudi Arabia bulletins. The epicentral distribution of aftershocks concentrates as a cluster around a small area between
28.5°N-28.7°N and 34.5°E-34.7°E. The area of aftershock concentrations is considered to be a high stress accumulation patch. This patch may be interpreted in terms of asperity or barrier.
The focal mechanisms of the mainshock and five events of its aftershocks were derived from the stereographic projection using polarity readings of P- wave first motions of local, regional and teleseismic stations. The present focal mechanisms represent normal faulting mechanisms with minor left lateral strike slip component. For most of the events, the nodal planes selected as the fault imply high similarity in strike and dip. They are related to a local striking NW- SE fault trend and dipping to the SW. The selected fault planes are in a good agreement with the aftershock distribution. The observation of similar striking aftershock fault plane solutions over the entire fault plane can be explained by the inhomogeneous source model.
Most of the relocated events which represent large stress drops in this sequence are clustered around the small area of the aftershock distribution. This clustering of aftershocks with large stress drops with respect to the mainshock marks an apparent stress concentration, possibly associated with the arrest of the main shock rupture propagation by a fracture barrier. Also, the geographic stress drop distribution of aftershocks shows another one of high stress released area located close to the location of the Gulf of Aqaba mainshock 1995.
Other data
| Title | Rupture Process Characteristics of August 1993 Aqaba Earthquake Sequence | Other Titles | خصائص عملية ا لكسر لتتابع زلازل العقبة أغسطس ( 1993 ) | Authors | Ali Kamel Abdel Fattah | Issue Date | 1997 |
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