The Use of Paleoseismic Data of Strong Earthquakes for Seismic Hazard Evaluations of the Dead Sea Transform.
Synthesis of paleoseismic data along the Dead Sea Transform shows that different segments have a specific pattern of time distribution of strong earthquake. It was found that during the last 20 ky the segments of the Arava and the Jordan valley have recurrence intervals of strong events, M > 6, of about 1 ky, while in the Hula valley the recurrence interval is 350 yr and in the Dead Sea segment it is 3-5 ky. However, despite differences between the segments some similarities can be shown, especially in the long time frame. At least two segments, the Arava and the Dead Sea, show a similar change in earthquake pattern over time. In both segments the probability of occurrence of strong earthquakes decreased gradually with time over the last 60 ky. In the southern Arava the magnitude range of earthquakes that occurred between 80 ka and 20 ka is M6.7 - M7 with average recurrence intervals of about 3 ky, whereas the magnitude range during the last 20 ky is M5.9 - M6.7 with average recurrence intervals of about 1 ky. Although the level of the recent seismic activity in these two segments is different, a similar trend of decrease in earthquake magnitudes with time was observed in the Dead Sea segment. Contrary to the paleoseismic evidences it is possible that the current seismic activity in the southern Arava, may point to a seismic gap. This may rely on the following observations: a. The temporal decrease in paleo- earthquake magnitude; b. The observation that the last large event occurred in A.D. 1068; c. The low rate of microseismicity recorded in the instrumental period since the early 1980's. In addition, these paleoseismological studies show that over the last 100 ka no evidence was found for earthquakes larger than M 7.5. It appears that there is an upper limit to the magnitude of the events that can be produced by the DST. It is suggested that this magnitude limit is an inherent characteristic of the DST which is controlled by the structure and the dimension of its segments.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 7221 Paleoseismology (8036);
- 7223 Earthquake interaction;
- and prediction (1217;
- 7230 Seismicity and tectonics (1207;