Examination of mineral assemblage and chemical composition in the fracture zone of the Nojima Fault at a depth of 1140 m: Analyses of the Hirabayashi NIED drill cores     

Tatsuo Matsuda  Takashi Arai  Ryuji Ikeda  Kentaro Omura  Kenta Kobayashi  Hiroyuki Sano  Takashi Sawaguchi  Hidemi Tanaka  Tomoaki Tomita  Naoto Tomida  Satoshi Hirano  Akiko Ymazaki 《Island Arc》2001,10(3-4):422-429

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Hardened foliated fault gouge from the Nojima Fault zone at Hirabayashi: Evidence for earthquake lightning accompanying the 1995 Kobe earthquake?   总被引：2，自引：0，他引：2  

Yuji Enomoto  Fumio Asuke  Zhong Zheng  Hiroyuki Ishigaki 《Island Arc》2001,10(3-4):447-456

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NIED seismic moment tensor catalogue for regional earthquakes around Japan: quality test and application   总被引：4，自引：0，他引：4  

Atsuki Kubo  Eiichi Fukuyama  Hiroyuki Kawai  Kenichi Nonomura 《Tectonophysics》2002,356(1-3)

We have examined the quality of the National Research Institute for Earth Science and Disaster Prevention (NIED) seismic moment tensor (MT) catalogue obtained using a regional broadband seismic network (FREESIA). First, we examined using synthetic waveforms the robustness of the solutions with regard to data noise as well as to errors in the velocity structure and focal location. Then, to estimate the reliability, robustness and validity of the catalogue, we compared it with the Harvard centroid moment tensor (CMT) catalogue as well as the Japan Meteorological Agency (JMA) focal mechanism catalogue. We found out that the NIED catalogue is consistent with Harvard and JMA catalogues within the uncertainty of 0.1 in moment magnitude, 10 km in depth, and 15° in direction of the stress axes. The NIED MT catalogue succeeded in reducing to 3.5 the lower limit of moment magnitude above which the moment tensor could be reliably estimated. Finally, we estimated the stress tensors in several different regions by using the NIED MT catalogue. This enables us to elucidate the stress/deformation field in and around the Japanese islands to understand the mode of deformation and applied stress. Moreover, we identified a region of abnormal stress in a swarm area from stress tensor estimates.  相似文献   

Chemical Features of White Micas from the Piemonte Calc-schists, Western Alps and Implications for K–Ar Ages of Metamorphism     

Hiroyuki Takeshita  Chitaro Gouzu  Tetsumaru Itaya   《Gondwana Research》2004,7(2):457-466

Anomalously large chemical ranges in muscovite-paragonite and muscovite-celadonite systems are observed in white micas from the Piemonte calcschists in the Chisone valley area, internal western Alps. The petrographical and chemical observations on white mica strongly suggest that most mica crystals with high Na/K ratios in the chlorite zone are of detrital origin, and were derived from the pre-Alpine high-temperature metamorphic sequence such the Caledonian and/or Variscan. Submicroscopic muscovite (Ms) - paragonite (Pg) composite aggregates occur in the chlorite zone and their EPMA analyses give an apparent chemical composition range from Ms_0.6Pg_0.4 to Ms_0.2Pg_0.8. In the rutile zone, the paragonite content of the white micas is less than 20%, suggesting that the white micas have been homogenized during the Alpine metamorphism even if detrital white micas existed.Metamorphic mica is also very heterogeneous. The total range in Si content becomes wider with increasing of metamorphic grade: 3.22–3.39 pfu for the chlorite zone, 3.07–3.45 pfu for the chloritoid zone and 3.06–3.59 pfu for the rutile zone. This clearly indicates that the micas have experienced significant retrogressive chemical reactions during cooling and exhumations of the host schists.The detrital white mica in the chlorite zone has not reset well in its K-Ar system during the Alpine subduction-related metamorphism. The wide range of the white mica K-Ar ages from 115 to 41 Ma must be due to a mixture of various amounts of detrital white mica in the separates. This feature is also observed in the chloritoid zone though the age variation is not so large as that in the chlorite zone. In contrast, the mica in the rutile zone, which was higher than 450°C, has been reset completely during Alpine HP metamorphism.  相似文献   

Symmetropy of Fault Patterns: Quantitative Measurement of Anisotropy and Entropic Heterogeneity     

Kazuyoshi Z. Nanjo  Hiroyuki Nagahama  Eiji Yodogawa 《Mathematical Geology》2005,37(3):277-293

The purpose of the effort in this paper is to show symmetropy of fault patterns. This quantity can be considered as a measure of entropic heterogeneity and anisotropy. We describe this measure based on the discrete Walsh transform. The specific results of its applications are obtained as follows. When a rock specimen undergoes creep in a laboratory experiment, the fault propagation can be monitored by the decrease of symmetropy. Moreover, in a fault model with self-organized criticality, fault patterns of critical states and subcritical states are distinguished by the behavior of the symmetropy: subcritical fault patterns show almost constant value of symmetropy but it takes various values during critical states. These results demonstrate that symmetropy idea can be used for the quantification of fault patterns.  相似文献   

Late Quaternary faulting along the western margin of the Poronaysk Lowland in central Sakhalin, Russia     

Hiroyuki Tsutsumi  Yasuhiro Suzuki  Andrei I. Kozhurin  Mihail I. Strel'tsov  Takeyuki Ueki  Hideaki Goto  Koji Okumura  Rustam F. Bulgakov  Hiroyuki Kitagawa 《Tectonophysics》2005,407(3-4):257-268

Sakhalin Island straddles an active plate boundary between the Okhotsk and Eurasian plates. South of Sakhalin, this plate boundary is illuminated by a series of M_w 7–8 earthquakes along the eastern margin of the Sea of Japan. Although this plate boundary is considered to extend onshore along the length of Sakhalin, the location and convergence rate of the plate boundary had been poorly constrained. We mapped north-trending active faults along the western margin of the Poronaysk Lowland in central Sakhalin based on aerial photograph interpretation and field observations. The active faults are located east of and parallel to the Tym–Poronaysk fault, a terrane boundary between Upper Cretaceous and Neogene strata; the active faults appear to have reactivated the terrane boundary at depth in Quaternary time. The total length of the active fault zone on land is about 140 km. Tectonic geomorphic features such as east-facing monoclinal and fault scarps, back-tilted fluvial terraces, and numerous secondary faults suggest that the faults are west-dipping reverse faults. Assuming the most widely developed geomorphic surface in the study area formed during the last glacial maximum at about 20 ka based on similarities of geomorphic features with those in Hokkaido Island, we obtain a vertical component of slip rate of 0.9–1.4 mm/year. Using the fault dip of 30–60°W observed at an outcrop and trench walls, a net slip rate of 1.0–2.8 mm/year is obtained. The upper bound of the estimate is close to a convergence rate across the Tym–Poronaysk fault based on GPS measurements. A trenching study across the fault zone dated the most recent faulting event at 3500–4000 years ago. The net slip associated with this event is estimated at about 4.5 m. Since the last faulting event, a minimum of 3.5 m of strain, close to the strain released during the last event, has accumulated along the central portion of the active strand of the Tym–Poronaysk fault.  相似文献   

Source process of a long-period event at Kilauea volcano, Hawaii   总被引：1，自引：0，他引：1  

Hiroyuki Kumagai  Bernard A. Chouet  Phillip B. Dawson 《Geophysical Journal International》2005,161(1):243-254

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Calculation of Surface Waves For A Thin Basin Structure Using A Direct Boundary Element Method With Normal Modes   总被引：1，自引：0，他引：1  

Hiroyuki Fujiwara  Hiroshi Takenaka 《Geophysical Journal International》1994,117(1):69-91

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Diurnal variations of the planetary boundary layer observed with anL-band clear-air doppler radar     

Hiroyuki Hashiguchi  Manabu D. Yamanaka  Toshitaka Tsuda  Mamoru Yamamoto  Takuji Nakamura  Tatsuhiro Adachi  Shoichiro Fukao  Toru Sato  Daniel L. Tobing 《Boundary-Layer Meteorology》1995,74(4):419-424

Based on continuous observations of the planetary boundary layer (PBL) with anL-band (1357.5 MHz) boundary-layer radar (BLR) at a hilly location in Japan, we have discovered that on clear days, a thin enhanced echo layer corresponding to the top of the PBL (or mixed layer) appeared at about 500 m height in the morning and ascended to about 1500 m in the afternoon. Strong upward velocities were observed below the echo layer (or inside the PBL), reaching 1500 m in the afternoon.  相似文献   

Sedimentary humic acid and fulvic acid as surface active substances     

Kohji Hayase  Hiroyuki Tsubota 《Geochimica et cosmochimica acta》1983,47(5):947-952

Surface tension of sedimentary fulvic acid (FA) and humic acid (HA) with molecular weight from < 10,000 to > 300,000 was measured at 5°C and 25°C, over a wide range of concentrations (0.114-107.4 g/l) at pH 8. HA was in the form of sodium humate. Surface tension decreases with an increase in HA and FA concentration and both HA and FA were found to be surface active materials with FA exhibiting the lowest surface tension (31 dynes/cm).Plots of surface tension vs. log concentration gave two straight lines with a break at a certain concentration similar to surfactants. From the concentration at the break point, aggregation concentration (AGC) was determined. For HA with molecular weight above 10,000, the AGC decreased with an increase in molecular weight. The more hydrophobic the HA, the greater was the tendency to form aggregates. Surface excess (surface concentration) was determined (2.3 × 10^?10?5.5 × 10^?10mol/cn²) from the slope of the plot of surface tension vs. log concentration for concentrations lower than the AGC. Adsorption of HA into the surface layer increased with increasing molecular weight of HA.  相似文献