Earthquakes

Re-Evaluating the Seismicity of the Jordan-Dead Sea Transform System

Najib Abou Karaki

Dept. of Geology - Univ. of Jordan. Amman-Jordan

 

Abstract

The Jordan Dead Sea Transform System (JDT), is the major source of seismic hazard in the northwestern zone of the Arabian Plate and the entire Sinai-Palestine Plate. Many attempts to evaluate seismic hazard in the zone were based on catalogues of historical and instrumental seismicity of the region, which present important shortcomings. A critical revision of the seismicity of the region is made. We illustrate the methods employed by giving some examples, corresponding to the historical and instrumental periods. The revision process applied to the JDT seismicity data, minimizes error accumulation, helps in the identification of true events and improves the homogeneity and accuracy of the catalogues.

 

Conclusions

Up to date most of the seismic hazard studies made for the JDT, were based upon historical seismicity catalogues and routine epicentral distributions. As has been shown by the samples examined, the data contain serious uncertainties. Such seismic hazard analyses are bound to lead to distorted evaluations of the level of seismicity in the zone. This applies, in particular, to some of the frequency magnitude relationships proposed for segments of the JDT. The quality of such relationships and the seismic hazard evaluations is obviously dependent upon the quality of the basic data used to obtain them. We propose a simple formula to test the chronology assigned to historical earthquakes. A careful examination of instrumentally determined epicenters should be carried out by performing relative locations whenever it becomes possible. Focal mechanisms are scarce in the region. Therefore there is a need to estimates those of small events, which should be used in conjuction with neotectonic information and satellite imagery.

 

 

- References

 

- Source: Geology of Jordan and Adjacent Areas (Proceedings of the 5th Jordanian Geological conference & 3rd Conference on the Geology of the middle East GEOCOME III)

Amman 3-5 October 1994