Origin of the Palau and Yap trench-arc systems     

Kazuo Kobayashi 《Geophysical Journal International》2004,157(3):1303-1315

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Data archives of seismic fault-induced damage   总被引：1，自引：0，他引：1  

Kazuo Konagai   《Soil Dynamics and Earthquake Engineering》2005,25(7-10):559-570

The study of earthquake engineering requires an understanding of various processes by which structures are seriously damaged. For this, archiving available data in a systematic way will be quite necessary. Taskforces of both Japan Society of Civil Engineers (JSCE) and Japan Geotechnical Society (JGS), with a mission of establishing remedial measures for fault-inflicted damage to civil infrastructures, have been investigating previous examples of fault-related damages. Some of their important activities were further expanded as a subject of EqTAP project (Development of Earthquake and Tsunami Disaster Mitigation Technologies and Their Integration for the Asia-Pacific Region). This paper introduces some examples from the JSCE/JGS/EqTAP Data Archives, which can give some hints for rational remedial or design measures for civil-infrastructures whose constructions across faults were/are unavoidable.  相似文献   

Correcting the Smoothing Effect of Ordinary Kriging Estimates   总被引：2，自引：0，他引：2  

Jorge Kazuo Yamamoto 《Mathematical Geology》2005,37(1):69-94

The smoothing effect of ordinary kriging is a well-known dangerous effect associated with this estimation technique. Consequently kriging estimates do not reproduce both histogram and semivariogram model of sample data. A four-step procedure for correcting the smoothing effect of ordinary kriging estimates is shown to be efficient for the reproduction of histogram and semivariogram without loss of local accuracy. Furthermore, this procedure provides a unique map sharing both local and global accuracies. Ordinary kriging with a proper correction for smoothing effect can be revitalized as a reliable estimation method that allows a better use of the available information.  相似文献   

Quantitative assessment on the influence of heavy rainfall on the crystalline schist landslide by monitoring system -case study on Zentoku landslide, Japan   总被引：2，自引：1，他引：2  

Yong Hong  Hiromasa Hiura  Kazuo Shino  Kyoji Sassa  Hiroshi Fukuoka 《Landslides》2005,2(1):31-41

On Shikoku Island, which is one of the four main islands of Japan, a large number of large-scale crystalline schist landslides have been revealed and are being monitored by an observation system. Seasonal heavy rainfall is the most active meteorological factor that can threaten the stability of this kind of site-specific landslide. In this paper, on the basis of the study of the rainfall-related behavior of a typical crystalline schist landslide, the Zentoku landslide, by analyzing the precisely and continuously observed piezometric and movement data, a method was developed to quantitatively assess the effect of heavy rainfall on a large-scale landslide. The results indicated that heavy rainfall-induced landslide displacement shows good correlation with the variation of groundwater levels. Variations of groundwater level have been simulated with the use of a tank model. The simulation using this model permits the change in water levels for future rainfall events to be predicted. By combining the predicted results with the empirical relation between displacements and water levels, rainfall-induced landslide movement during extreme rainfall events can be estimated in advance. The effect of heavy rainfall on sliding behavior can be quantified in terms of the change in displacement. Thus warning information or advisories for the local residents can be provided.  相似文献   

Mineralogy and geochemistry of granitoids from Kinnaur region,Himachal Higher Himalaya,India: Implication on the nature of felsic magmatism in the collision tectonics     

Brajesh Singh  Santosh Kumar  Masao Ban  Kazuo Nakashima 《Journal of Earth System Science》2016,125(7):1329-1352

Felsic magmatism in the southern part of Himachal Higher Himalaya is constituted by Neoproterozoic granite gneiss (GGn), Early Palaeozoic granitoids (EPG) and Tertiary tourmaline-bearing leucogranite (TLg). Magnetic susceptibility values (<3 ×10^?3 SI), molar Al₂ O ₃/(CaO + Na₂ O + K ₂O) (≥1.1), mineral assemblage (bt–ms–pl–kf–qtz ± tur ± ap), and the presence of normative corundum relate these granitoids to peraluminous S-type, ilmenite series (reduced type) granites formed in a syncollisional tectonic setting. Plagioclase from GGn (An₁₀–An₃₁) and EPG (An₁₅–An₃₃) represents oligoclase to andesine and TLg (An₂–An₁₅) represents albite to oligoclase, whereas compositional ranges of K-feldspar are more-or-less similar (Or₈₈ to Or₉₅ in GGn, Or₈₆ to Or₉₇ in EPG and Or₈₇ to Or₉₄ in TLg). Biotites in GGn (Mg/Mg + Fe^t= 0.34–0.45), EPG (Mg/Mg + Fe^t= 0.27–0.47), and TLg (Mg/Mg + Fe^t= 0.25–0.30) are ferribiotites enriched in siderophyllite, which stabilised between FMQ and HM buffers and are characterised by dominant 3Fe\(\rightleftharpoons \)2Al, 3Mg\(\rightleftharpoons \)2Al substitutions typical of peraluminous (S-type), reducing felsic melts. Muscovite in GGn (Mg/Mg + Fe^t=0.58–0.66), EPG (Mg/Mg + Fe^t=0.31?0.59), and TLg (Mg/Mg + Fe^t=0.29–0.42) represent celadonite and paragonite solid solutions, and the tourmaline from EPG and TLg belongs to the schorl-elbaite series, which are characteristics of peraluminous, Li-poor, biotite-tourmaline granites. Geochemical features reveal that the GGn and EPG precursor melts were most likely derived from melting of biotite-rich metapelite and metagraywacke sources, whereas TLg melt appears to have formed from biotite-muscovite rich metapelite and metagraywacke sources. Major and trace elements modelling suggest that the GGn, EPG and TLg parental melts have experienced low degrees (～13, ～17 and ～13%, respectively) of kf–pl–bt fractionation, respectively, subsequent to partial melting. The GGn and EPG melts are the results of a pre-Himalayan, syn-collisional Pan-African felsic magmatic event, whereas the TLg is a magmatic product of Himalayan collision tectonics.  相似文献   

Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region          下载免费PDF全文

Dan M. Arriesgado  Hiroyuki Kurokochi  Yuichi Nakajima  Yu Matsuki  Wilfredo H. Uy  Miguel D. Fortes  Wilfredo L. Campos  Kazuo Nadaoka  Chunlan Lian 《Marine Ecology》2016,37(4):786-800

Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (F_ST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change.  相似文献   

Dynamic evolution of nutrient discharge under stormflow and baseflow conditions in a coastal agricultural watershed in Ishigaki Island,Okinawa, Japan     

Ariel C. Blanco  Kazuo Nadaoka  Takahiro Yamamoto  Koichi Kinjo 《水文研究》2010,24(18):2601-2616

Excessive terrestrial nutrient loadings adversely impact coral reefs by primarily enhancing growth of macroalgae, potentially leading to a phase‐shift phenomenon. Hydrological processes and other spatial and temporal factors affecting nutrient discharge must be examined to be able to formulate effective measures for reducing nutrient export to adjacent reefs. During storm events and baseflow periods, water samples were obtained from the tropical Todoroki River, which drains an intensively agricultural watershed into Shiraho coral reef. In situ nutrient analyzers were deployed for 6 months to hourly measure dissolved nutrient (NO₃⁻‐N and PO₄³⁻‐P) concentrations. Total phosphorus (TP) and suspended solid concentration (TSS) were increased by higher rainfall intensity (r = 0·94, p < 0·01) and river discharge Q (r = 0·88, p < 0·01). In contrast, NO₃⁻‐N concentration tends to decrease drastically (e.g. from 3 to 1 mg l⁻¹) during flood events. When base flow starts to dominate afterwards, NO₃⁻‐N manifested an increasing trend, but decreases when baseflow discharge becomes low. This counter‐clockwise hysteresis for NO₃⁻‐N highlights the significant influence of groundwater discharge. N delivery can therefore be considered a persistent process compared to sediment and P discharge, which are highly episodic in nature. Based on GIS analysis, nutrient concentration along the Todoroki River was largely affected by the percentage of sugarcane/bare areas and bedrock type. The spatial distribution of N concentration in the river reflects the considerable influence of subsurface geology—higher N levels in limestone‐dominated areas. P concentrations were directly related to the total length of artificial drainage, which enhances sediment transport. The use of high‐resolution monitoring data coupled with GIS‐based spatial analysis therefore enabled the clarification of control factors and the difference in the spatio‐temporal discharge characteristics between N and P. Thus, although erosion‐reduction schemes would reduce P discharge, other approaches (e.g. minimize fertilizer) are needed to reduce N discharge. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Subgrade model for transient response analysis of multiple embedded bodies     

Kazuo Konagai  Toyoaki Nogami 《地震工程与结构动力学》1994,23(10):1097-1114

During the dynamic response of multiple partially or fully embedded structures, the subgrade medium at the sides of the structures not only generates the soil-structure interaction forces but also transmits the motions from one structural body to others. With Winkler's hypothesis, these forces and motions are formulated in the time-domain in a simple form utilizing the frequency-domains formulations. The validity of the developed formulations is examined using small-scale-model test results obtained for piles in a synthetic ground. A numerical example is provided to demonstrate the approach proposed and the formulations developed. The simplified time-domain formulations are found to be numerically efficient and yet capable of predicting the behaviour reasonably well.  相似文献   

Glacio-geophysical implication of an NNSS positioning in and around Syowa Station, East Antarctica     

Kazuo Shibuya 《Journal of Geodynamics》1986,6(1-4)

Utilization of the two-wave NNSS receiver drastically improved the positioning accuracy on the ice sheet of Antarctica. The NNSS positioning gives us 3 m three-dimensional convergence with 25 accepted satellite passes, and is most useful for the measurement of ice flow velocity. The flow velocity vectors along Route S-H-Z on Mizuho plateau, East Antarctica were obtained by estimating positional change of glaciological traverse stations after 7 years' interval. The transformation of the coordinate system was necessary before the comparison of the positioning in 1973 by the geodetic traverse method on the Bessel Reference Ellipsoid with that in 1980 by the satellite Doppler method on the NWL-8E Ellipsoid. NNSS receiving experiments at astronomical datum point in Syowa Station enabled us to estimate the translation of the coordinate origin of the Bessel Reference Ellipsoid against the geocentric NWL-8E Ellipsoid and correction terms for coordinate transformation. The obtained flow velocity is 15 m/a at H17 of around 1000 m a.s.l. and 70 m/a at Z2 of around 2000 m a.s.l. with ±6% uncertainty, and is too large to be explained only by the laminar flow of the ice sheet. The obtained velocity vectors are found to be mostly parallel to the maximum slope of the free-air gravity anomaly contours and can be interpreted as the ice sheet sliding down the slope of the subglacial mound of 2400 m relative height from the average subglacial bedrock topography. If such bedrock sliding occurrs over the whole region of Mizuho Plateau, the related thinning of the ice sheet may be detected by the precise measurement of the height change of the same marker station. By dynamically modelling the ice sheet and substituting the observed parameters such as precipitation, principal strain rate, etc., into the equation of ice thickness change the submergence velocity of around −1 m/a is expected and will be detected by carefully designed repetitive NNSS receiving experiments after several year's interval.  相似文献   

An aeromagnetic survey around Syowa station, East Antarctica     

Kazuo Shibuya  Katsutada Kaminuma 《Journal of Geodynamics》1986,6(1-4)

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