Static and dynamic fault parameters of the Saitama earthquake of July 1, 1968     

Katsuyuki Abe   《Tectonophysics》1975,27(3):223-238

The source mechanism of the Saitama earthquake (36.07°N,139.40°E, M_s = 5.4) of July 1, 1968, is studied on the basis of P-wave first motion, aftershock, long-period surface-wave data and low-magnification long-period seismograms recorded in the nearfield. A precise location of the aftershocks is made using P and S—P time data obtained by a micro-earthquake observatory network. The synthetic near-field seismograms based on the Haskell model are directly compared with the observed near-field seismograms for wave form and amplitude to determine the dynamic fault parameters. The results obtained are as follows: source geometry, reverse dip slip with considerable right-lateral strike-slip component; dip direction, N6°E; dip angle 30°; fault dimension, 10 × 6 km²; rupture velocity, 3.4 km/sec in the direction S30°E; average dislocation, 92 cm; average dislocation velocity, 92 cm/sec; seismic moment, 1.9 · 10²⁵ dyn-cm; stress drop, 100 bar. The effective stress is about the same as the stress drop. For major earthquakes in the Japanese Islands, the dislocation velocity, .D, is found to be proportional to the stress drop, σ. This relation can be expressed by .D - (β/μ)σ, where β is the shear velocity and μ is the rigidity. This result has an importance in engineering seismology because the stress drop scales the seismic motion in the vicinity of an earthquake fault.  相似文献   

Source model of Noto-Hanto-Oki earthquake tsunami of 7 February 1993   总被引：1，自引：0，他引：1  

Kuniaki Abe  Masami Okada 《Pure and Applied Geophysics》1995,144(3-4):621-631

A source model was discussed for a small tsunami accompanied by the Noto-Hanto-Oki earthquake (M _s 6.6), striking Japan on 7 February, 1994. Assuming a fault model under the sea bottom, we estimated the focal parameters jointly, using synthesized tsunami source spectra as well as the tsunami numerical simulation. The fault proposed by this study consists of a plane sized 15×15 km, dipping N47°W with the dip angle of 42°, which is almost pure reverse fault (slip angle 87°) with a dislocation of 1 meter. The numerical simulation shows that the shallow sea in the source region caused a comparatively long recurring tsunami (the periods are 12–18 minutes) in spite of its small size. The model fault is corresponding to an aftershock area of this earthquake.  相似文献   

Physical state of the very early Earth   总被引：1，自引：0，他引：1  

Yutaka Abe 《Lithos》1993,30(3-4):223-235

The earliest surface environment of the Earth is reconstructed in accordance with the planetary formation theory. Formation of an atmosphere is an inevitable consequence of Earth's formation. The atmosphere near the close of accretion is composed of 200 300 bars of H₂ and H₂O, and several tens of bars of CO and CO₂. Either by the blanketing effect of the proto-atmosphere or heating by large planetesimal impacts a magma ocean is formed during accretion. We can distinguish three stages for the thermal evolution of the magma ocean and proto-crust. Stage 0 is characterized by a super-liquidus (or completely molten) regime near the surface. At this stage the surface of the Earth is covered by a super-liquidus magma ocean. No chemical differentiation is expected during this stage. Once the energy flux released by planet formation decreases to the 200 W/m² level the super-liquidus magma ocean then disappears within a time interval of 1 m.y. This is the transition from stage 0 to 1. Stage 1 is characterized by a partially molten magma ocean. In the magma ocean consisting of 20 30% partial melt, heat transport is controlled by melt-solid separation (a type of compositional convection) rather than thermal convection. Chemical differentiation of the mantle mainly occurs in this stage. Once the energy flux drops to the 160 W/m² level, more than 90% of water vapor in the proto-atmosphere condense to form the proto-oceans. Several tens of bars of CO and CO₂ remain in the atmosphere just after formation of the oceans. Water oceans are occasionally evaporated by large impacts. After each such event, recondensation of the ocean takes several hundred years. Although the surface is covered by a chilled proto-crust, it is short-lived because of extensive volcanic resurfacing activity as well as meteorite impacts resurfacing. This stage ends when the energy flux drops to 0.1 1 W/m² level. The duration time of stage 1 is estimated to be several hundred million years (the best estimate is about 400 m.y.). Stage 2 is characterized by solid state convection. This stage continues to the present day. One of the most important change on the proto-Earth is the transition from stage 1 to 2, which occurs several hundred million years after the Earth formation. Long-lived crust is formed only after this transition.  相似文献   

No Problems to Report     

Abe M. Kalaf 《Ground Water Monitoring & Remediation》1990,10(4):79-79

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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   

Global mapping of the degree of space weathering on asteroid 25143 Itokawa by Hayabusa/AMICA observations     

Masateru Ishiguro  Takahiro Hiroi  David J. Tholen  Sho Sasaki  Yuji Ueda  Tokuhiro Nimura  Masanao Abe  Beth E. Clark  Aya Yamamoto  Fumi Yoshida  Ryosuke Nakamura  Naru Hirata  Hideaki Miyamoto  Yasuhiro Yokota  Tatsuaki Hashimoto  Takashi Kubota  Akiko M. Nakamura  Robert W. Gaskell  Jun Saito 《Meteoritics & planetary science》2007,42(10):1791-1800

Abstract— We obtained color images of near‐Earth asteroid 25143 Itokawa by the Hayabusa multiband imaging camera to characterize the regional color properties. Images were obtained for the whole disk from the gate position (GP) and home position (HP) at a spatial resolution of 0.8–3.7 m/pixel. Whole‐disk spectra are adjusted to the telescopic data obtained by the University of Hawai'i's 88‐inch telescope using the Eight Color Asteroid Survey (ECAS) system. The disk‐resolved measurements show large variations in the three visible channels. We present a map of an index related to the degree of space weathering, which has been newly developed based on laboratory measurements. We find large variations in the degree of space weathering on Itokawa. Fresh materials are observed in regions of steep slopes and craters, whereas mature materials are ubiquitously distributed. This result suggests that pristine ordinary chondrite‐like materials have been exposed through weathered layers by excavation. By also examining close‐up images obtained during touchdown rehearsal, we find that most rocks in Itokawa's rough terrains are weathered. Instead of a regolith blanket, the surface of this small asteroid is covered with weathered rocks and gravels.  相似文献   

印度喀拉拉邦雨影区流域系统形态分析及其水文意义(英文)   总被引：1，自引：0，他引：1  

Jobin THOMAS  Sabu JOSEPH  K.P. THRIVIKRAMJI  George ABE 《地理学报(英文版)》2011,21(6):1077-1088

The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin (PRB) lies on the rain shadow region of the southern Western Ghats, India, where climate showed marked intra-basin variation. A morphometric analysis was done to evaluate the drainage characteristics of PRB using topographical maps and digital elevation data. PRB was divided into eighteen 4th order basins (SB1-SB18), distributed along various climatic gradients. Lower order streams mostly dominate PRB and drainage pattern is a function of relief and structure. The terrain is highly dissected and prone to soil erosion during heavy storms and the elongated shape of PRB enables easier flood management. The influence of climate on drainage characteristics was evidently emphasized in basin morphometry. Four distinctively different classes were identified based on the morphometric similarities. The significance of morphometric analysis on the hydrological characterization is discussed and the relevance of the present study in water harvesting has been explicated.  相似文献   

Near-infrared spectrophotometry of Asteroid 25143 Itokawa from NIRS on the Hayabusa spacecraft     

Kohei Kitazato  Beth E. Clark  Shinsuke Abe  Takahiro Hiroi  Paul A. Abell  Faith Vilas 《Icarus》2008,194(1):137-145

A photometric analysis of the S-type Asteroid 25143 Itokawa is performed over multiple wavelengths ranging from 0.85 to 2.10 μm based on disk-resolved reflectance spectra obtained with the Hayabusa near-infrared spectrometer (NIRS). We derive the global photometric properties of Itokawa in terms of Hapke's photometric model. We find that Itokawa has a single-scatter albedo that is 35-40% less than that of Asteroid 433 Eros. Itokawa also has a single-particle phase function that is more strongly back-scattering than that of Eros. Despite its hummocky surface strewn with large boulders, Itokawa exhibits an opposition effect. However, the total amplitude of the opposition surge for Itokawa was estimated to be less than unity while Eros and other S-type asteroids have been found to have model values exceeding unity. The wavelength dependence of the opposition surge width reveals that coherent backscatter contributes to the opposition effect on Itokawa's surface. The photometric roughness of Itokawa is well constrained to a value of 26° ± 1° which is similar to Eros, suggesting that photometric roughness models the smallest surface roughness scale for which shadows exist.  相似文献   

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   

Space weathered rims found on the surfaces of the Itokawa dust particles     

Takaaki Noguchi  Makoto Kimura  Takahito Hashimoto  Mitsuru Konno  Tomoki Nakamura  Michael E. Zolensky  Ryuji Okazaki  Masahiko Tanaka  Akira Tsuchiyama  Aiko Nakato  Toshinori Ogami  Hatsumi Ishida  Ryosuke Sagae  Shinichi Tsujimoto  Toru Matsumoto  Junya Matsuno  Akio Fujimura  Masanao Abe  Toru Yada  Toshifumi Mukai  Munetaka Ueno  Tatsuaki Okada  Kei Shirai  Yukihiro Ishibashi 《Meteoritics & planetary science》2014,49(2):188-214

On the basis of observations using Cs‐corrected STEM, we identified three types of surface modification probably formed by space weathering on the surfaces of Itokawa particles. They are (1) redeposition rims (2–3 nm), (2) composite rims (30–60 nm), and (3) composite vesicular rims (60–80 nm). These rims are characterized by a combination of three zones. Zone I occupies the outermost part of the surface modification, which contains elements that are not included in the unchanged substrate minerals, suggesting that this zone is composed of sputter deposits and/or impact vapor deposits originating from the surrounding minerals. Redeposition rims are composed only of Zone I and directly attaches to the unchanged minerals (Zone III). Zone I of composite and composite vesicular rims often contains nanophase (Fe,Mg)S. The composite rims and the composite vesicular rims have a two‐layered structure: a combination of Zone I and Zone II, below which Zone III exists. Zone II is the partially amorphized zone. Zone II of ferromagnesian silicates contains abundant nanophase Fe. Radiation‐induced segregation and in situ reduction are the most plausible mechanisms to form nanophase Fe in Zone II. Their lattice fringes indicate that they contain metallic iron, which probably causes the reddening of the reflectance spectra of Itokawa. Zone II of the composite vesicular rims contains vesicles. The vesicles in Zone II were probably formed by segregation of solar wind He implanted in this zone. The textures strongly suggest that solar wind irradiation damage and implantation are the major causes of surface modification and space weathering on Itokawa.  相似文献