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Abstract. The amplitude attenuation and phase dispersion for Love and Rayleigh waves in the period range 50 to 300 sec is determined from two earthquakes by digital techniques.A distribution of Q, or anelasticity, is determined for the upper mantle which satisfies the amplitude decay data for Love and Rayleigh waves and which is consistent with available body wave data. An argument is made for a longitudinal wave Q of about 2.4 to 2.6 times the Q for shear waves. This implies that very small losses are im·olved in pure compre~sion compared to the losses in shear. This is an argument against the importance of certain mechanisms, such as thermoelastic losses, in the mantle. The Q for shear waves in the upper 400 km of the mantle seems to vary from about 50 to about 150. The Q for mantle Rayleigh waves is greater than the Q for mantle Love waves, both theoretically and experimentally. HoweYer, it is predicted that QR becomes less than QL at some period shorter than 50 sec, the crossover period being diagnostic of the thickness of the 'Q crust' or lithosphere.

Body waves from a finite moving source are investigated. Ray theory is used to obtain a long‐range approximation for the surface displacements from a buried horizontal force. A weak velocity gradient in the medium is assumed, and the curvature of the earth is replaced by an equivalent additional velocity gradient. The displacements are then integrated over a finite line to simulate a disturbance moving with constant speed. Results indicate that the finiteness of the source is manifested in a factor of the form e‐iXsinX/X and that the derivation of the fault length and the velocity of rupture of earthquakes from the spectra of body waves is possible. The results are similar to those obtained earlier for seismic surface waves, except that for body waves X depends on both polar coordinates of the station with respect to the source. The method can be extended to other types of common faulting.

A study of major earthquake occurrence along the Dead Sea transform (35.50-36.50 E; 27.20-37.50 N) during the past four millenia has been attempted. Geological, archaeological, biblical, historical, and seismologicaJ evidence were integrated in an effort to quantify the space-time distribution of seismicity in the said province. The ovcrM1 earthquake activity in the conterminous Near East indicates a stable pattern and appeared to have been stationary over the examined time window. About 110 earthquakes in the magnitude range 6.7 < ML _• 8.3 affected the area during the past 2500 years. Of these, 42 originated along the Dead Sea fault system itself, while 68 were imported from the Helenic-Cyprian arcs and the Anatolian-Elburz-Zagros fault systems. These events were responsible for the repeated destruction of many cultural centers. In the Dead Sea region proper, the major seismic activity since 2100 B.C.E. (Before Christian Era), has been confined to the vicinity of its eastern shore with extremal seismicity at its southern tip near the prehistorical site of Bab-a-Dara'a (31 ø 15'N, 35 o 32'E). This may constitute the first solid evidence that the Biblical "cities of the Plain" (Sodom, Gommorah, etc.) were located there. Recent studies of earthquake deformations in the Lisan deposits near Bab-a-Dara'a, agree with our findings. At the present time, a magnitude 6• earthquake is pending at the northern edge of the Levant rift, with its average recurrence interval (83 years) exceeded by one standard deviation (32 years). INTRODUCTIONThe Near East is probably the only region on Earth where evidence for earthquake activity has been documented in one way or another over the past four millenia. The interpretation of these valuable data, in the light of current tectonic models [Freund, 1965; Ben-Menahem and A boodi, 1971, Ben-Menahem et al., 1976] and with the aid of tools provided by modern seismology, calls for a comparative analysis of all available geological, historical, archaeological, and seismological findings. The present study reports results from these four complementary disciplines. Our well-defined geological province extends along some 1140 kin: from offshore southern tip of the Sinai peninsula to the collision zone between Arabia and Anatolia and the East Anatolian fault system at the Kara-Su junction. Major earthquakes with epicenters outside this region, such as the Zagros and north Anatolian faultsystems, Aegean Sea, Crete, Greece, and the eastern Mediterranean basin, were also felt and even caused severe damage in the Near East. A schematic map of the region is shown in Figure 1. The numbers giving the displacements represent their cummulative values over a period of about 10 my. Figure 2 shows epicenters of earthquakes with ML >_ 7.4 (solid circles) that were felt in Jerusalem The main sources of this epoch are Talmudic and post-Talmudic literature. Roman, Arabic and medieval literature, reports and books of pilgrims, historians, chronologists, travellers, and priests; eyewitness reports of the effects ...

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