Seismic response analysis of laterally inhomogeneous ground with emphasis on strains     

M. Kamiyama  T. Satoh 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):877-884

The objective of this paper is to make it clear how strain behaviors are affected by the lateral inhomogeneity of ground based on both theoretical simulation and array observation of earthquake motions. We use a two-dimensional pseudo-spectral method to numerically obtain strain motions as well as acceleration motions. We applied the method to some model grounds, which have typical inhomogeneity in the horizontal direction, to estimate general features of strains and accelerations. In addition, the technique was also applied to a site where subsurface irregularity is typically found and an array observation system of earthquake motions was densely deployed. In the latter application of the method, we placed emphasis on comparisons between the observed and simulated motions.  相似文献   

Small-Amplitude Disturbances In A Radiating And Scattering Grey Medium Ii. Solutions Of Given Real Wave Number <Emphasis Type="BoldItalic">k</Emphasis>     

Noboru?KanekoEmail author  Kazuhiko?Morita  Tetsuya?Satoh  Kimitake?Hayasaki 《Astrophysics and Space Science》2005,299(3):263-306

We study the fundamental modes of radiation hydrodynamic waves arising from one-dimensional small-amplitude initial fluctuations with wave number k in a radiating and scattering grey medium using the Eddington approximation. The dispersion relation analyzed is the same as that of Paper I (Kaneko et al., 2000), but is solved as a quintic in angular frequency ω while a quadratic in k ² in Paper I. Numerical results reveal that wave patterns of five solutions are distinguished into three types of the radiation-dominated and type 1 and type 2 matter-dominated cases. The following wave modes appear in our problem: radiation wave, conservative radiation wave, entropy wave, Newtonian-cooling wave, opacity-damped and cooling-damped waves, constant-volume and constant-pressure diffusion modes, adiabatic sound wave, cooling-damped and drag–force-damped isothermal sound waves, isentropic radiation-acoustic wave, and gap mode. The radiation-dominated case is characterized by the gap between the isothermal sound and isentropic radiation-acoustic speeds within which there is not any acoustic wave propagating with real phase speed. One of the differences between type 1 and type 2 matter-dominated cases is the connectivity of the constant-volume diffusion mode, which originates from the radiative mode in the former case, while from the Newtonian-cooling wave in the latter case. Analytic solutions are derived for all wave modes to discuss their physical significance. The criterion, which distinguishes between radiation-dominated and type 1 matter-dominated cases, is given by Γ₀ = 9, where Γ₀ = C _p ^(tot)/C _V ^(tot) is the ratio of total specific heats at constant pressure and constant volume. Waves in a scattering grey medium are also analyzed, which provides us some hints for the effects of energy and momentum exchange between matter and radiation.  相似文献   

Paleoenvironmental interpretations of Quaternary reef deposits based on comparisons of 10 selected modern and fossil larger foraminifera from the Ryukyu Islands, Japan     

Kazuhiko  Fujita  Hiroaki  Shimoji  Koichi  Nagai 《Island Arc》2006,15(4):420-436

Abstract A new method for reconstructing depositional environments of larger foraminifera‐bearing limestones is proposed. First, depth and spatial distributions of empty tests of 10 foraminiferal taxa in a 1–2 mm size fraction were examined using 32 surface sediment samples collected from depths shallower than 200 m, located to the west of Miyako Island, Ryukyu Islands, northwest Pacific. Distributional ranges of empty tests in the 1–2 mm size fraction appear to be more limited than those including other size fractions in previous reports, partly because larger empty tests of each taxon are less easily transported than smaller ones. Multivariate analyses (Q‐mode cluster analysis and non‐metric multidimensional scaling ordination) based on binary (presence/absence) data of the 10 taxa delineate four sample groups, each of which corresponds to different depositional environments: nearshore zone/bay inlet; back‐reef to fore‐reef; outer shelf to shelf slope; and shelf slope distant from coral reefs. Next, these modern data were applied to reconstruct the depositional environment of a rock section distributed in the Shiratorizaki area (Irabu Island, Ryukyu Islands), which consists of larger foraminiferal limestone of the Pleistocene Ryukyu Group. Multivariate analyses were performed on the fossil plus the modern foraminiferal data to explore the possible relationship of the fossil associations with variations in modern associations, demonstrating that the fossil foraminiferal associations resemble the modern outer shelf associations. The modern analog technique was also applied to estimate paleobathymetry using fossil foraminiferal data. The results indicate that the section studied was deposited in outer shelf environments at depths between 53.5 and 98.6 m. These paleoenvironmental interpretations are consistent with previous studies based on sedimentary facies and the computer‐based expert system. The modern dataset and methods used in our work would be particularly useful for paleoenvironmental reconstructions of Quaternary reef and shelf carbonates along active margins of the northwest Pacific.  相似文献   

Synthetic Silica Glass for Trace Aluminium Determination in Quartz by Electron Microprobe     

Naoya Miyoshi  Hisao Satoh  Yoshiaki Yamaguchi  Harue Masuda 《Geostandards and Geoanalytical Research》2003,27(1):91-98

Five synthetic silica glasses have been prepared for microprobe determination of trace aluminium in quartz. The glasses were synthesized from tetraethoxysilane (TEOS) into which between 0 and 1431 μg g-¹ aluminium had been doped. The aluminium concentrations of the glasses were independently determined by ICP-AES analysis. X-ray wavelength shift in the Al Kα peak was minimised relative to unknown quartz samples when these glasses were used for calibration. A set of these five glasses yielded a linear calibration line, and are available for trace aluminium analysis of quartz in routine microprobe systems.  相似文献   

Compressional wave velocity of granite and amphibolite up to melting temperatures at 1 GPa   总被引：2，自引：0，他引：2  

Yoshitaka Aizawa  Kazuhiko Ito  Yoshiyuki Tatsumi 《Tectonophysics》2002,351(3):4108

Compressional wave velocities (V_P) at above-solidus temperatures and at 1 GPa were obtained for a granite and amphibolite, which are considered to be major constituents of the continental crust. The temperature variation of velocities showed that the V_P values of granite decreased with rising temperature, but substantially increased beyond the melting temperature (850–900 °C). Such an increase may be caused by the α–β transition of quartz. The velocities of amphibolite decreased linearly with increasing temperature and dropped sharply at temperatures above the solidus (700 °C), indicating that partial melting of amphibolite acts to significantly lower the seismic velocities.  相似文献   

Crustal structure and tectonics of the Hidaka Collision Zone, Hokkaido (Japan), revealed by vibroseis seismic reflection and gravity surveys     

Kazunori Arita  Takashi Ikawa  Tanio Ito  Akihiko Yamamoto  Matsuhiko Saito  Yasunori Nishida  Hideyuki Satoh  Gaku Kimura  Teruo Watanabe  Takeshi Ikawa  Toru Kuroda 《Tectonophysics》1998,290(3-4):197-210

This study is the first integrated geological and geophysical investigation of the Hidaka Collision Zone in southern Central Hokkaido, Japan, which shows complex collision tectonics with a westward vergence. The Hidaka Collision Zone consists of the Idon'nappu Belt (IB), the Poroshiri Ophiolite Belt (POB) and the Hidaka Metamorphic Belt (HMB) with the Hidaka Belt from west to east. The POB (metamorphosed ophiolites) is overthrust by the HMB (steeply eastward-dipping palaeo-arc crust) along the Hidaka Main Thrust (HMT), and in turn, thrusts over the Idon'nappu Belt (melanges) along the Hidaka Western Thrust (HWT). Seismic reflection and gravity surveys along a 20-km-long traverse across the southern Hidaka Mountains revealed hitherto unknown crustal structures of the collision zone such as listric thrusts, back thrusts, frontal thrust-and-fold structures, and duplex structures. The main findings are as follows. (1) The HMT, which dips steeply at the surface, is a listric fault dipping gently at a depth of 7 km beneath the eastern end of the HMB, and cutting across the lithological boundaries and schistosity of the Hidaka metamorphic rocks. (2) A second reflector is detected 1 km below the HMT reflector. The intervening part between these two reflectors is inferred to be the POB, which is only little exposed at the surface. This inference is supported by the high positive Bouguer anomalies along the Hidaka Mountains. (3) The shallow portion of the IB at the front of the collision zone has a number of NNE-dipping reflectors, indicative of imbricated fold-and-thrust structures. (4) Subhorizontal reflectors at a depth of 14 km are recognized intermittently at both sides of the seismic profile. These reflectors may correspond to the velocity boundary (5.9–6.6 km/s) previously obtained from seismic refraction profiling in the northern Hidaka Mountains. (5) These crustal structures as well as the back thrust found in the eastern end of the traverse represent characteristics of collisional tectonics resulting from the two collisional events since the Early Tertiary.  相似文献   

A direct numerical approach to the Chandrasekhar'sH-functions for arbitrary characteristic functions     

Kiyoshi Kawabata  Takehiko Satoh  Sueo Ueno 《Astrophysics and Space Science》1991,182(2):249-260

The purpose of this paper is to present a numerical technique to directly compute the Chandrasekhar'sH ()-function for anisotropic scattering in terms of the roots of the characteristic equations as well as the quadrature points of a certain degreen employed to approximate the definite integral involved in the basic equation. The principal feature of the algorithm proposed here is a compact computer code to enumerate _n C _m combinations ofn distinct integers {1,...,n} takenm at a time. With these quantities available, the coefficients of the polynomial equation of the characteristics equation can be readily computed for any given characteristic function, so that a standard technique such as the Laguerre method can be applied to find all the roots.It is shown that the results obtained for some representativeH()-functions using the present technique with relatively low-order formula (e.g.,n=7) are sufficiently accurate for all practical purposes.  相似文献   

The tsunami of 3 February 1605     

Hisashi Miyoshi  Kaname Satoh  Yoshinobu Tsuji 《Journal of Oceanography》1989,45(3):174-180

Whether the origins of the tsunami of 3 February 1605 were separated ones or a joined one, is one of the most important problems for Japanese society. When the marine knowledge has not been popularized, it has been considered that the damage pattern on Hachijo Island (including Kojima) was an important key to solving this question.It resembles the situation that the reports concerning the tsunami of 1 April 1946 were introduced to Japanese society under an internal disturbance just after the war, and we overlooked the most important consideration on the combination of tsunami and storm waves caused by the trade wind, and received this tsunami as an extraordinarily huge one.We studied the statistics of recent wind directions around Hachijo Island in January and February 1973, 1974, 1977, 1983, 1984, 1985, 1986 and 1987. And we believed that the probability was high that we could explain well that the damage pattern on Hachijo Island in 1605 was due to the combination of tsunami and storm waves caused by the monsoon.We need not, therefore, look back the damage pattern on Hachijo Island when we consider the fact that the necrologies of many temples in Shizuoka Prefecture record no death on 3 February 1605, proves to be the key to infer that the origins were separated ones.  相似文献   

Improving Representation of Tropical Cloud Overlap in GCMs Based on Cloud-Resolving Model Data     

Xianwen Jing  Hua Zhang  Masaki Satoh  Shuyun Zhao 《Acta Meteorologica Sinica》2018,32(2):233-245

The decorrelation length (L_cf) has been widely used to describe the behavior of vertical overlap of clouds in general circulation models (GCMs); however, it has been a challenge to associate L_cf with the large-scale meteorological conditions during cloud evolution. This study explored the relationship between L_cf and the strength of atmospheric convection in the tropics based on output from a global cloud-resolving model. L_cf tends to increase with vertical velocity in the mid-troposphere (w₅₀₀) at locations of ascent, but shows little or no dependency on w₅₀₀ at locations of descent. A representation of L_cf as a function of vertical velocity is obtained, with a linear regression in ascending regions and a constant value in descending regions. This simple and dynamic-related representation of L_cf leads to a significant improvement in simulation of both cloud cover and radiation fields compared with traditional overlap treatments. This work presents a physically justifiable approach to depicting cloud overlap in the tropics in GCMs.  相似文献   

Control algorithm for estimating future responses of active variable stiffness structure     

Kazuhiko Yamada  Takuji Kobori 《地震工程与结构动力学》1995,24(8):1085-1099

A control algorithm has been developed for controlling Active Variable Stiffness (AVS) structures. This algorithm analyses information of an observed seismic excitation, estimates the future structural responses and determines how to alter the structure stiffness. An objective structure is assumed to possess N on-off elements whose states are controlled by the proposed algorithm. That is, at a given moment t_k, (1) seismic excitation information is expressed by an Auto Regressive (AR) model as the identification model; (2) future excitation information is predicted using the AR model; (3) future responses due to predicted excitation are estimated; (4) based on the initial condition at t_k, the responses of 2^N possible structural states from t_k, to t_k+L are calculated; (5) the state which minimizes the input energy during t_L is selected; and (6) immediately after t_k, on-off elements are set up and subjected to the selected states. The effectiveness of the induced algorithm is confirmed by numerical experiments on a model of a three-storey building under sine and seismic excitations.  相似文献