Double seismic zone beneath the middle of Hokkaido, Japan, in the southwestern side of the Kurile Arc     

Sadaomi Suzuki  Tsutomu Sasatani  Yoshinobu Motoya 《Tectonophysics》1983,96(1-2)

The vertical section of microearthquakes, determined accurately by using the Hokkaido University network, shows two dipping zones (the double seismic zone) 25–30 km apart in the depth range of 80–150 km beneath the middle of Hokkaido in the southwestern side of the Kurile arc. Hypocentral distribution of large earthquakes (m_b > 4) based on the ISC (International Seismological Centre) bulletin also shows the double seismic zone beneath the same region. The hypocentral distribution indicates that the frequency of events occurring in the lower zone is four times greater than that in the upper zone. The difference in seismic activity between the two zones beneath Hokkaido is in contrast with the region beneath northeastern Honshu in the northeastern Japan arc.Composite focal mechanisms of microearthquakes and individual mechanisms of large events mainly characterize the down-dip extension for the lower zone as is observed beneath northeastern Honshu. For the upper zone, however, the stress field is rather complex and not necessarily similar to that beneath northeastern Honshu. This may be considered to indicate the influence of slab contortion or transformation in the Hokkaido corner between the Kurile and the northeastern Japan arcs.  相似文献   

CHIME age dating of monazites from metamorphic rocks and granitic rocks of the Ryoke belt in the Iwakuni area, Southwest Japan   总被引：2，自引：0，他引：2  

Kazuhiro  Suzuki  Mamoru  Adachi Terukazu  Nureki 《Island Arc》1996,5(1):43-55

Abstract CHIME (chemical Th-U-total Pb isochron method) ages were determined for monazite from gneisses and granitoids of the Ryoke belt in the Iwakuni area. The CHIME monazite ages are 99.6 ± 2.4, 98.9 ± 2.1 and 98.2 ± 5.7 Ma for the Ryoke gneiss, 90.7 ± 2.2, 89.7 ± 2.0 and 89.3 ± 2.2 Ma for the Tajiri Granite, 91.0 ± 3.2, 90.6 ± 3.2 and 89.9 ± 3.2 Ma for the Namera Granite, 89.3 ±3.3 and 88.6 ± 5.6 Ma for a small stock at Shimizu, and 87.3 ± 1.6 and 86.6 ± 2.1 Ma for the post-tectonic Shimokuhara Granite. The CHIME monazite ages, interpreted as the time of the first attainment at the amphibolite facies conditions for the gneisses and as the time of emplacement for the granites, respectively, agree with the field intrusive sequence. The present dating documented that the Ryoke metamorphism in the Iwakuni area reached the amphibolite facies conditions at ∼98 Ma, was complete at -87 Ma, the time of emplacement of the post-tectonic Shimokuhara Granite.  相似文献   

Moment tensors of earthquakes in and near the Tibetan Plateau and their scaling law     

Si-Hua Zheng  Ziro Suzuki 《地震学报(英文版)》1993,6(2):365-377

Moment tensors of eleven major earthquakes in the Tibetan Plateau and its surrounding region from 1966 to 1980 are estimated by generalized inverse technique. The seismic source time function and focal depth are immediately determined in the inversion. The results show that moment tensors of some events differ significantly from double couple, the deviation increases with decreasing plunge angle of null axis. All these events occurred in the upper crust, much shallower than those reported so far, for example, in NEIS Bulletin. Focal mechanism solution obtained from the moment tensors are consistent with the idea that the Indian plate collides northwards with the Eurasian plate and that an eastward spreading exists in the crust of the Tibetan Plateau. The stress drops for earthquakes of intraplate are systematically higher than those of earthquakes in suture zone. The source process duration becomes longer with seismic moment, but for the same seismic moment, the process duration for earthquakes in suture zone is about 1.4 times of those for intraplate event, these results suggest that the earthquakes near suture zone may be of a special characteristics in source process differently from those in intraplate. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 423 – 434, 1992.  相似文献   

A FE–BE method for dynamic analysis of dam–foundation–reservoir systems in the time domain     

Terumi Touhei  Tatsuo Ohmachi 《地震工程与结构动力学》1993,22(3):195-209

By coupling FEM and BEM, a numerical method was developed for dynamic response analyses of dam–foundation–reservoir systems in the time domain. During formulation, the weighted residual procedure was applied to the coupling of several equations of motion for solid and fluid in the FE and BE regions, and an algorithm similar to the Newmark beta procedure was finally obtained. The algorithm is advantageous in that it takes into account all the effects of dam–foundation, dam–reservoir and reservoir–foundation interactions, as well as of the absorption of both elastodynamic and hydrodynamic waves at the boundaries of the foundation and the reservoir. To demonstrate the validity of the present method, the impulsive response of a dam–foundation–reservoir system was calculated using the algorithm, and showed a good agreement with the existing results obtained by other researchers.  相似文献   

Dust Trails of 8P/Tuttle and the Unusual Outbursts of the Ursid Shower     

P. JenniskensE. Lyytinen  M.C. de LignieC. Johannink  K. JobseR. Schievink  M. LangbroekM. Koop  P. GuralM.A. Wilson  I. YrjöläK. Suzuki  H. OgawaP. de Groote 《Icarus》2002,159(1):197-209

We calculate the position of dust trails from comet 8P/Tuttle, in an effort to explain unusual Ursid meteor shower outbursts that were seen when the comet was near aphelion. Comet 8P/Tuttle is a Halley-type comet in a 13.6-year orbit, passing just outside of Earth's orbit. We find that the meteoroids tend to be trapped in the 12:14 mean motion resonance with Jupiter, while the comet librates in a slightly shorter period orbit around the 13:15 resonance. It takes 6 centuries to decrease the perihelion of the meteoroid orbits enough to intersect Earth's orbit, during which time the meteoroids and comet separate in mean anomaly by 6 years, thus explaining the 6-year lag between the comet's return and Ursid outbursts. The resonances also prevent dispersion along the comet orbit and limit viewing to only one year in each return. We identified past dust trail encounters with dust trails from 1392 (Dec. 1945) and 1378 (Dec. 1986) and predicted another outburst on 2000 December 22 at around 7:29 and 8:35 UT, respectively, from dust trails dating to the 1405 and 1392 returns. This event was observed from California using video and photographic techniques. At the same time, five Global-MS-Net stations in Finland, Japan, and Belgium counted meteors using forward meteor scatter. The outburst peaked at 8:06±07 UT, December 22, at zenith hourly rate ∼90 per hour, and the Ursid rates were above half peak intensity during 4.2 h. We find that most Ursid orbits do scatter around the anticipated positions, confirming the link with comet 8P/Tuttle and the epoch of ejection. The 1405 and 1392 dust trails appear to have contributed similar amounts to the activity profile. Some orbits provide a hint of much older debris being present as well. This work is the strongest evidence yet for the relevance of mean motion resonances in Halley-type comet dust trail evolution.  相似文献   

The Properties of Supernova 1997cy Associated with GRB 970514     

Turatto M  Suzuki T  Mazzali PA  Benetti S  Cappellaro E  Danziger IJ  Nomoto K  Nakamura T  Young TR  Patat F 《The Astrophysical journal》2000,534(1):L57-L61

The extraordinary SN 1997cy associated with GRB 970514 has been observed photometrically and spectroscopically for nearly 2 yr. At the time of discovery, SN 1997cy was the brightest supernova (SN) ever observed (MV相似文献   

Os, Pb, and Nd isotope geochemistry of the Permian Emeishan continental flood basalts: Insights into the source of a large igneous province   总被引：4，自引：0，他引：4  

Ji-Feng Xu  Katsuhiko Suzuki  Yi-Gang Xu  Jie Li 《Geochimica et cosmochimica acta》2007,71(8):2104-2119

The nature of the source of continental flood basalts (CFB) is a highly debated topic. Proposed mantle sources for CFBs, including both high- and low-Ti basalts, include subcontinental lithospheric mantle (SCLM), asthenospheric mantle, and deep, plume-related mantle. Re-Os isotope systematics can offer important constraints on the sources of both ocean island basalts (OIB) and CFB, and may be applied to distinguish different possible melt sources. This paper reports the first Re-Os isotope data for the Late Permian Emeishan large igneous province (LIP) in Southwest China. Twenty one CFB samples including both low- and high-Ti basalts from five representative sites within the Emeishan LIP have been analyzed for Os, Nd, and Pb isotopic compositions. The obtained Os data demonstrate that crustal assimilation affected Os isotopic compositions of some Emeishan basalt samples with low Os concentrations but not all of the samples, and the Emeishan basalts with high Os contents likely experienced the least crustal contamination. The low and high-Ti basalts yield distinct Os signatures in terms of ¹⁸⁷Os/¹⁸⁸Os and Os content. The low-Ti basalt with the highest Os concentration (400 ppt) has a radiogenic Os isotopic composition (γOs(t), +6.5), similar to that of plume-derived OIB. Because the Os isotopic composition of basalts with relatively high Os concentrations (typically >50 ppt) likely represents that of their mantle source, this result implies a plume-derived origin for the low-Ti basalts. On the other hand, the high-Ti basalts with high Os concentration (over 50 ppt) have unradiogenic Os isotopic signatures (γOs(t) values range from −0.8 to −1.4), suggesting that a subcontinental lithosphere mantle (SCLM) component most likely contributed to the generation of these magmas. Combining Pb and Nd isotopic tracers with the Os data, we demonstrate that the low-Ti basaltic magmas in the Emeishan CFB were mainly sourced from a mantle plume reservoir, whereas the high-Ti basaltic magmas were most likely derived from a SCLM reservoir or were contaminated by a significant amount of lithospheric mantle material during plume-related magma ascent through the SCLM.  相似文献   

Hybridization of the probability perturbation method with gradient information     

Kent Johansen  Jef Caers  Satomi Suzuki 《Computational Geosciences》2007,11(4):319-331

Geostatistically based history-matching methods make it possible to devise history-matching strategies that will honor geologic knowledge about the reservoir. However, the performance of these methods is known to be impeded by slow convergence rates resulting from the stochastic nature of the algorithm. It is the purpose of this paper to introduce a method that integrates qualitative gradient information into the probability perturbation method to improve convergence. The potential of the proposed method is demonstrated on a synthetic history-matching example. The results indicate that inclusion of qualitative gradient information improves the performance of the probability perturbation method.  相似文献   

Double-planed deep seismic zone and anomalous structure in the upper mantle beneath northeastern Honshu (Japan)   总被引：1，自引：0，他引：1  

Akira Hasegawa  Norihito Umino  Akio Takagi  Ziro Suzuki 《Tectonophysics》1979,57(1):1-6

Seismicity located by using the most recent data obtained from the high-gain seismograph network of Tohoku University shows that the deep seismic zone beneath northeastern Honshu, Japan, is composed of two thin planes which are parallel to each other and are 30–40 km apart. Focal mechanisms derived from the earthquakes in the upper plane are reverse-faulting, or, some of them, down-dip compression. As a contrast, those in the lower plane are down-dip extension. The location of the upper boundary of the descending lithospheric slab, inferred from the arrival-time difference between ScS and ScSp waves and from the travel-time anomaly of intermediate-depth earthquakes observed at the small-scale seismic array, coincides exactly with the upper plane of the double-planed deep seismic zone. Anelasticity (1/Q) structure of the upper mantle consists of three distinct zones: a high-Q (Qs− 1500) inclined lithospheric slab, an intennediate-Q (Qs−350) land-side mantle between the Pacific coast and the volcanic front, and a low-Q (Qs − 100) land-side mantle between the volcanic front and the coast of the Japan Sea.The evidence obtained here provides valuable information as to the definition of the type of mechanism producing the plate motion beneath island arcs.  相似文献   

Experimental study of the alteration process of labradorite in acid hydrothermal solutions     

Yoshiro Tsuzuki  Kazuhiro Suzuki 《Geochimica et cosmochimica acta》1980,44(5):673-683

Labradorite was altered artificially by HC1 solution ranging from M = 1 to M = 0.003 at 245 and 230°C. The products of alteration were examined by X-ray diffraction, electron microscopy, electron diffraction, infrared spectroscopy and the electron microprobe and the solution was analyzed chemically.Amorphous silica only was formed in solutions with M_HCl = 1 and M_HCl = 0.3. In a solution with M_HCl = 0.2, amorphous silica was initially formed, later dissolved and replaced by kaolinite. A mixture of microcrystalline boehmite and amorphous aluminosilicate was formed, altering to kaolinite in solutions with M_HCl = 0.1 and 0.3. Small amounts of kaolinite were initially formed but the alteration soon stopped in solution with M_HCl = 0.003. Relationships between the alteration processes and pH of the solutions can be roughly explained by using solubility diagrams assuming the congruent dissolution of labradorite and precipitation of the products in partial equilibrium. However, these assumptions are not valid with strongly acid solutions.The rate of dissolution of labradorite is controlled not only by its surface area, but also by the diffusion of matter through the layer of alteration products.  相似文献