Tsunami and mechanism of great earthquakes     

Katsuyuki Abe 《Physics of the Earth and Planetary Interiors》1973,7(2):143-153

The relation between tsunamis and sea-bottom deformations associated with the Kurile Islands earthquake of 1969 and the Tokachi-Oki earthquake of 1968 is studied on the basis of a fairly complete set of seismological and tsunami data. The seismic results are included in the calculation of static crustal deformations. The calculated deformations are compared with the tsunami source area as obtained by the inverse refraction diagram, the first motion of tsunami waves, and the height of the sea-level disturbance at the source. It is found that such deformations as predicted by the seismic results can quantitatively explain the source parameters of tsunamis. These findings strongly favor the idea that tsunamis are generated by tectonic deformations rather than by large submarine landslides and slumps. This conclusion is supported by additional analyses for the 1964 Niigata, 1944 Tonankai, 1933 Sanriku earthquakes. For the 1946 Nankaido earthquake, the source deformation responsible for the tsunami generation is of much greater magnitude than that for seismic waves.  相似文献   

Formation of a ‘magma ocean’ on the terrestrial planets due to the blanketing effect of an impact-induced atmosphere     

Takafumi Matsui  Yutaka Abe 《Earth, Moon, and Planets》1986,34(3):223-230

We show that the surface of a planet growing by planetesimal impact is heated over the melting temperature of the surface materials due to the blanketing effect of an impact induced H₂O atmosphere with the present H₂O abundance of the Earth even when the accretion time is as long as 10⁸ years. Hence, a magma ocean covering the entire surface was formed on the Earth and Moon and other terrestrial planets during their formations.  相似文献   

Distribution of maximum water levels due to the Japan Sea Tsunami on 26 May 1983     

Kuniaki Abe  Hiroshi Ishii 《Journal of Oceanography》1987,43(3):169-182

By measuring the maximum water level of the traces attained by the Japan Sea Tsunami on 26 May 1983, we obtained the distribution along the west coast of the northeast Japan. The level reaches a maximum at the coast eastward of the epicenter and decreases with the relationship 8.6e ^–0.017x (m) with distancex (km) measured from the coast nearest to the epicenter. A small increase of levels was observed at coasts to the south of the tsunami source having distance larger than 200 km. With the aid of tide gauge records we revealed an excitation of edge wave which brought about the small increase of levels at the southern coast. In comparison with the decrease with distance obtained on the coasts of the main islands of Japan, some noticeable peaks were observed at several small islands. It is suggested that the reason why a short period component is predominant for the initial wave motion of tsunami is that the source region has depth of 3, 000 meters. The feature of wave period is discussed in comparison with that of the 1964 Niigata Tsunami.  相似文献   

Fighting pollution     

Abe H. Siemens 《Marine Policy》1977,1(1):70-71

The role of the US Coast Guard in protecting the marine environment. A policy statement by the Chief of the Office of Research and Development of the US Coast Guard.¹  相似文献   

A pump-sampler as a method of collecting plankton and its preliminary operation     

Akihiko Kuwahara  Tsuneyuki Abe  Masayuki Shimono  Makoto Kashiwai  Masatosi Sinoda 《Journal of Oceanography》1973,29(3):106-112

A pump-sampler was designed to study the distribution of marine plankton and its possible relationship with the temperature and salinity of the water. Sea water was pumped up through a 2 inch diameter hose and plankton contained in it was collected on a filter cup (2 inches in diameter, 139 meshes/inch) without being damaged. The filter cup, when clogged by plankton organisms, was washed by spraying with about 100 cu. cm of water. The differences between two continuous with an interval of more than 3–4 seconds could be detected.A preliminary operation along a 2.82 km course in Maizuru Bay was carried out simultaneously with temperature-salinity measurements at sampling intervals of 30 m. Temperature was measured by a thermistor resistance thermometer, and salinity was measured by a salinometer with a subsample of water which was collected from an additional opening of the pump-sampler. The temperature-salinity record showed that four zones of water were characterized.It was found that wide variation of plankton counts indicated dense concentrations of particular species or group of species, and on the mesoscale it was possible to examine the size of the aggregation.  相似文献   

Implementation of Particle-scale Rotation in the 3-D Lattice Solid Model     

Yucang Wang  Steffen Abe  Shane Latham  Peter Mora 《Pure and Applied Geophysics》2006,163(9):1769-1785

In this study, 3-D Lattice Solid Model (LSMearth or LSM) was extended by introducing particle-scale rotation. In the new model, for each 3-D particle, we introduce six degrees of freedom: Three for translational motion, and three for orientation. Six kinds of relative motions are permitted between two neighboring particles, and six interactions are transferred, i.e., radial, two shearing forces, twisting and two bending torques. By using quaternion algebra, relative rotation between two particles is decomposed into two sequence-independent rotations such that all interactions due to the relative motions between interactive rigid bodies can be uniquely decided. After incorporating this mechanism and introducing bond breaking under torsion and bending into the LSM, several tests on 2-D and 3-D rock failure under uni-axial compression are carried out. Compared with the simulations without the single particle rotational mechanism, the new simulation results match more closely experimental results of rock fracture and hence, are encouraging. Since more parameters are introduced, an approach for choosing the new parameters is presented.  相似文献   

Seismic structure and seismogenesis off Sanriku region, northeastern Japan   总被引：2，自引：0，他引：2  

Narumi Takahashi  Shuichi Kodaira  Tetsuro Tsuru  Jin-Oh Park  Yoshiyuki Kaneda  Kiyoshi Suyehiro  Hajimu Kinoshita  Shintaro Abe  Minoru Nishino  Ryota Hino 《Geophysical Journal International》2004,159(1):129-145

  相似文献   

Simulation of the Micro-physics of Rocks Using LSMearth   总被引：4，自引：0，他引：4  

D. Place  F. Lombard  P. Mora  S. Abe 《Pure and Applied Geophysics》2002,159(9):1911-1932

-- The particle-based Lattice Solid Model (LSM) was developed to provide a basis to study the physics of rocks and the nonlinear dynamics of earthquakes (M0ra and Place, 1994; Place and Mora, 1999). A new modular and flexible LSM approach has been developed that allows different micro-physics to be easily included in or removed from the model. The approach provides a virtual laboratory where numerical experiments can easily be set up and all measurable quantities visualised. The proposed approach provides a means to simulate complex phenomena such as fracturing or localisation processes, and enables the effect of different micro-physics on macroscopic behaviour to be studied. The initial 2-D model is extended to allow three-dimensional simulations to be performed and particles of different sizes to be specified. Numerical bi-axial compression experiments under different confining pressure are used to calibrate the model. By tuning the different microscopic parameters (such as coefficient of friction, microscopic strength and distribution of grain sizes), the macroscopic strength of the material and can be adjusted to be in agreement with laboratory experiments, and the orientation of fractures is consistent with the theoretical value predicted based on Mohr-Coulomb diagram. Simulations indicate that 3-D numerical models have different macroscopic properties than in 2-D and, hence, the model must be recalibrated for 3-D simulations. These numerical experiments illustrate that the new approach is capable of simulating typical rock fracture behaviour. The new model provides a basis to investigate nucleation, rupture and slip pulse propagation in complex fault zones without the previous model limitations of a regular low-level surface geometry and being restricted to two-dimensions.  相似文献   

Modelling three‐dimensional non‐linear seismic performance of elevated bridges with emphasis on pounding of girders     

Ping Zhu  Masato Abe  Yozo Fujino 《地震工程与结构动力学》2002,31(11):1891-1913

Unseating of bridge girders/decks during earthquakes is very harmful to the safety and serviceability of bridges. Evidence from recent severe earthquakes indicates that in addition to damage along longitudinal direction, lateral displacement and rotation of bridge girders caused by pounding to adjacent girders can also lead to unseating. To simulate this effect, 3D modelling of the dynamic performance of whole bridge structures, including pounding, is needed strongly. This paper presents a 3D model that is practically suitable to precisely analyse pounding between bridge girders. Experiments have been conducted to verify the proposed pounding model. The 3D non‐linear modelling of steel elevated bridges is also discussed. A general‐purpose dynamic analysis program for bridges, namely dynamic analysis of bridge systems (DABS) has been developed. Seismic analyses on a chosen three‐span steel bridge are conducted for several cases including pounding as a case study. The applicability of the proposed pounding model is illustrated by the computations. The effects of poundings on the response of bridge girders are discussed and the computation results are given. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Tectonic implications of the large shioya-oki earthquakes of 1938     

Katsuyuki Abe 《Tectonophysics》1977,41(4):269-289

The tectonic processes taking place along the southern part of the Japan trench are discussed on the basis of the focal mechanism of the 1938 Shioya-Oki event which consists of the five large earthquakes of M_s = 7.4, 7.7, 7.8, 7.7 and 7.1. Detailed analyses of seismic waves and tsunamis are made for each of these earthquakes, and the dislocation parameters are obtained. The total seismic moment amounts to 2.3 · 10²⁸ dyn.cm. The five earthquakes are grouped into either a low-angle thrust type or a nearly vertical normal-fault type. These mechanisms are common with other great earthquakes of the northwestern Pacific belt, and can be explained in terms of the interaction between the oceanic and continental plates. The vertical displacement inferred from the seismic results is in approximate agreement with the precise level data over the period from 1939 and 1897. This agreement suggests that the rate of the strain accumulation at the preseismic time is very small in the epicentral area. Repeated levelings at the postseismic time reveal a large-scale recovery of the coseismic subsidence. The postseismic deformation is one-third to one-half of the coseismic displacement. The time constant of the recovery is estimated to be 5 years or less. This type of deformation may be a manifestation of viscoelasticity of a weak zone underlying the continent. The amount of dislocation, together with the longterm seismicity, suggests a seismic slip rate of about 0.4 cm/year, which is one order of magnitude smaller than that for the adjacent regions. This suggests that a large part of the plate motion is taking place aseismically in this region. The tectonic process now taking place in the southern Japan trench can be considered to represent a stage just prior to a complete detachment of the sinking portion of the oceanic plate.  相似文献