Modeling of the runup heights of the Hokkaido-Nansei-Oki tsunami of 12 July 1993

The Hokkaido-Nansei-Oki earthquake (M _w 7.7) of July 12, 1993, is one of the largest tsunamigenic events in the Sea of Japan. The tsunami magnitudeM _t is determined to be 8.1 from the maximum amplitudes of the tsunami recorded on tide gauges. This value is larger thanM _w by 0.4 units. It is suggested that the tsunami potential of the Nansei-Oki earthquake is large forM _w . A number of tsunami runup data are accumulated for a total range of about 1000 km along the coast, and the data are averaged to obtain the local mean heightsH _n for 23 segments in intervals of about 40 km each. The geographic variation ofH _n is approximately explained in terms of the empirical relationship proposed byAbe (1989, 1993). The height prediction from the available earthquake magnitudes ranges from 5.0–8.4 m, which brackets the observed maximum ofH _n , 7.7 m, at Okushiri Island.     

A study of tropospheric wave disturbances over India in winter

The wave disturbances in the troposphere over north and central India during winter when the subtropical westerlies prevail in the upper air over the area have been investigated by power-and cross-spectrum analysis. The power-spectrum study revealed the existence of basically two systems of periods 10.0–12.5 days and 4.5–5.5 days in the middle and upper troposphere. Both the long-and short-period systems have been found to be propagating eastwards at rates 5° and 10° long./day respectively. In both the cases lower temperatures are found to the east of the troughs. It is also noted that these systems build up the meridional temperature gradient and hence strengthen the upper tropospheric westerlies. Synoptic study of the transient systems is presented.     

Three-dimensional elastic wave scattering and diffraction due to a rigid cylinder embedded in an elastic medium by a point source

The formal solutions of displacement field to the problem of elastic wave scattering and diffraction due to an infinitely long rigid cylinder embedded in an infinite elastic medium by an impulsive point source have been obtained in the integral form. The integrals for the reflected and the diffracted waves both in the shadow zone and in the illuminated zone are evaluated asymptotically for the early time motion by the Reisdue-Cagniard method and the Saddle-point-Cagniard method.Numerical results of the diffractedP, S andPS waves at a fixed circum-distance from the surface of the rigid cylinder show noticeably that (1) the energy partition for the diffractedS wave is small in comparison with that for the diffractedP wave, (2) the wave form of the diffractedS wave is broader and more diffused than that of the diffractedP wave, (3) the direction of the radial motions of the diffractedP andS waves varies as a function of the observational point, and (4) the energy partition for the diffractedP wave is much smaller than that for the direct or the reflectedP waves.This paper has been presented at the 46th Annual International Meeting of Society of Exploration Geophysicists in Houston, Texas, Oct. 28, 1976.     

Analysis of kinematic seismic response of tapered piles

In the present work, a two-phase analysis is used to assess the lateral movement of a tapered pile due to kinematic seismic loading resulted from earthquakes. First, the free-field horizontal displacement of the ground due to earthquake is estimated using available theory of wave propagation. Second, these estimated soil movements are imposed on the taper pile in a closed-form solution to compute the pile response. The governing differential equation for an arbitrary pile segment is obtained, which includes the free-field horizontal movement estimated from the first phase. The equation is solved explicitly to obtain the horizontal deflection. Parametric studies show that tapered piles tend to be more flexible than uniform piles of the same volume and length under earthquake loading, which is soundly interesting.     

双平方根单程波动方程叠前τ偏移方法

本文将常规双平方根（DSR）单程波动方程从深度域变换到双程垂直走时（τ）域，由此推导出可从数学上实现“沉降观测”的单程波DSR传播算子. 其递归波场延拓算法包含波数域针对常速背景的相移处理和空间域针对横向速度扰动的相位校正，可以应对上覆地层速度横向变化对构造成像的影响. 结合零炮检距、零时间成像条件，提出了在τ域进行波场延拓与成像的DSR方程叠前偏移新方法. 为了克服其全三维偏移算法在实际应用中可能面临的困难，本文采用稳相近似，在crossline常炮检距偏移理论基础上推导了实用的共方位角叠前τ偏移方法. 数值试验表明，DSR方程叠前τ偏移在强横向非均匀介质中的成像精度与分辨率优于传统的时间域成像技术.     

中层大气中重力波饱和机制的数值分析

通过对向上传播的重力波波包在中层大气中的非线性传播过程进行数值模拟,讨论中层大气中重力波的饱和机制.数值模拟结果表明,向上传播的重力波波包的扰动振幅在接近波包的本征水平相速度之前随高度单调增长,而当波振幅接近本征水平相速度时,在对流不稳定区域出现等位温面的翻转,同时波振幅的增长达到饱和（波振幅随高度不发生变化）.小尺度对流在等位温面的翻转和波饱和发生后产生,随后波包开始破碎,这些非线性过程的最终结果产生湍流.表明导致重力波饱和的关键因素是等位温面的翻转而不是诸如波破碎、湍流、波-流相互作用等其他的一些物理过程.     

波浪和海底底床的相互作用(1)-不同模型下的波浪衰减分析

分析了造成波浪衰减几种力学机制，并针对不同模型海底底床下的波浪衰减，以及有限深底床和无限深底床的波浪衰减进行了计算比较，认为造成波浪衰减的力学机制直接和底床砂质的性质相关。     

Elastic waves in visco-elastic half-space generated by various vehicle loads

In this paper, the response of a visco-elastic half-space subjected to moving loads with static and dynamic components is investigated. Four types of vehicle loads are considered, including the moving point load, uniformly distributed wheel load, elastically distributed wheel load, and a train load simulated as a sequence of elastically distributed wheel loads. In each case, the influence of the moving loads traveling in the subsonic, transonic and supersonic ranges on the dynamic responses of the half-space is studied. The parametric study conducted herein enables us to grasp insight into the mechanism of wave propagation for a visco-elastic half-space under moving loads.     

Wave propagation in a seven-story reinforced concrete building: I. Theoretical models

For transient, high frequency, and pulse like excitation of structures in the near field of strong earthquakes, the classical design approach based on relative response spectrum and mode superposition may not be conservative. For such excitations, it is more natural to use wave propagation methods. In this paper (Part I), we review several two-dimensional wave propagation models of buildings and show results for theoretical dispersion curves computed for these models. We also estimate the parameters of these models that would correspond to a seven-story reinforced concrete building in Van Nuys, California. Ambient vibration tests data for this building imply vertical shear wave velocity β_z=112 m/s and anisotropy factor β_x/β_z=0.55 for NS vibrations, and β_z=88 m/s and β_x/β_z=1 for EW vibrations. The velocity of shear waves propagating through the slabs is estimated to be about 2000 m/s. In the companion paper (Part II), we estimate phase velocities of vertically and horizontally propagating waves between seven pairs of recording points in the building using recorded response to four earthquakes.     

不同温压条件下弹性波在岩石中传播速度的实验研究

对以岩浆岩为主的岩石类型进行了不同温压条件下弹性波传播速度的实验研究，结果表明：（１）岩石的物质组成是决定弹性波传播速度的主要因素。以岩浆岩为例，由酸性到基性波速呈增加趋势；（２）岩石中弹性波的传播速度随环境条件改变而变化。一般说来，随温压条件的升高而升高