Strain and tilt fields due to the fault spreading over several layers in a multi-layered medium are investigated.
Using the matrix method, integral representations for the strain and tilt filds caused by a dislocation with an arbitrary orientation, at any depth, in a multi-layered medium are obtained from the analytical expressions of the static displacement fields derived by SATO (1971).
Machine program for the static deformations (displacements, strains and tilts) is completed, by which contour or vector map of each component can also be obtained. Some numerical examples by using this program are Presented for the purpose of elucidating the effect of multi-layered structure on the strain and tilt fields at the surface.
It is concluded that the effect caused by soft layer at the surface (representing sedimentary cover) is significant on both the magnitudes of the deformation fields and their patterns.

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Clear multiple core phases from east Russian deep earthquakes with epicentral distance about 9 degrees are recorded at the Dodaira observatory. Through the spectral analysis of these core phases such as ScS and sScS group the attenuation factor Q for the upper 600km and the whole mantle is determined. The average Q value in the whole mantle is estimated at 290 for the frequency range 0.015-0.035cps, and that of the upper 600km is estimated at 150, 220, 260 for the range 0.015-0.035, 0.035-0.095 and 0.30-0.80cps, respectively.

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Integrating a point source solution derived in the preceding paper by KAWASAKI et al. (1973), theoretical surface displacements due to various types of propagating faults located in a semi-infinite medium are obtained and compared with those for an infinite medium. General features of wave forms are summarized as follows;
(1) Except for SP wave and Rayleigh wave portions, horizontal components U_r and U_φ of free surface displacement are approximately given by doubling the corresponding displacements for an infinite medium. The vertical component U_z is much disturbed by the free surface.
(2) The SP wave has an appreciable amplitude comparable to that of P wave as pointed out for a point source case by KAWASAKI et al. (1973). Especially in such cases as shallow sources propagate upward, the SP wave becomes a remarkably marked phase. Hence, careful examinations for SP wave are required on analysing the near-field seismograms, especially for shallow focus earthquakes.

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A Model in which the plate (lithosphere) is thickening with time away from oceanic ridges is presented here and details of numerical experiments are reported. In this model, the plate develops on the balance of the heat budget between input heat flow from asthenosphere, release of solidification heat at the plate-asthenosphere boundary, and cooling from the surface. It is demonstrated that the thickening plate model is fully consistent with the various geophysical observations such as gravity anomalies, surface heat flow, water depth in ocean basins and physical properties of the asthenosphere and the lithosphere.

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Ttransmission coefficients at the entrance of an estuary were calculated for lateral incidence of periodic waves along a coast. At particular values of kd=(n+1)π or (n+1/2)π(k, wave number; d, half width of a channel and n, non-negative integers), there exists a relation ζ^(m)_c=δ_{m, n+1} or ζ^(m)_B=-i. δ_{m, n}, where m=0, 1, 2, etc., ζ^(m)_c (ζ^(m)_s) denotes symmetric (anti-symmetric) mode in channel and δ_{m, n} is Kronecker delta. Using the calculated transmission coefficients, the transmitted energy into a channel is estimated. Am-Plitude and phase distribution in the vicinity of an estuary entrance were calculated. These results show the concentration of energy along the leeward bank of a channel. Using an approximate method, we obtained a simple and convenient relation between the transmission coefficient for lateral incidence and that for incidence with arbitrary angle.

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Detailed laboratory experiments have been performed on the frictional characteristics of various rocks. Frictional behavior greatly depends not only upon rock type, but upon such surface condition as roughness. The behavior of soft rock is more influenced by roughness than that of hard rock. Frictional behavior is classified into the four types: (1) the behavior characterized by both the predominant force drop at initial sliding and stable sliding subsequent to the predominant force drop, (2) the behavior characterized by both the predominant force drop at initial sliding and a series of sticks and slips, (3) frictional sliding occurring stably without any sudden slip, and (4) the behavior characterized only by a series of sticks and slips. The intermediate behavior between type 3 and type 4 is also observed: stable sliding precedes stick-slip.
Frictional force increases with displacement (displacement hardening). This is attributed to the development of adhesive or abrasive wear (gouge) particles on sliding surfaces with increasing displacement at an applied constant normal force, The scatter of the measured values of friction on nominally identical specimens under nominally identical conditions is related to the difference in the amount of wear particles developed on sliding surfaces between runs. The experimental relation between friction and the amount of gouge particles is analyzed from a theoretical viewpoint. It is found that stick-slip occurs only when the amount of wear particles is small, and that frictional sliding takes place stably when the gouge is developed abundantly over the whole of the sliding surfaces. The controlling mechanism of friction for uniform soft rocks, such as limestone and marble, is distinctly different from that for such rocks as granite and monzonite which contain various minerals of different hardness. The effects of normal stress and loading rate on friction are also investigated.

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