Evaluating the susceptibility of landslide landforms in Japan using slope stability analysis: a case study of the 2016 Kumamoto earthquake     

Chi-Wen Chen  Hongey Chen  Lun-Wei Wei  Guan-Wei Lin  Tomoyuki Iida  Ryuji Yamada 《Landslides》2017,14(5):1793-1801

This study analyzed 267 landslide landforms (LLs) in the Kumamoto area of Japan from the database of about 0.4 million LLs for the whole of Japan identified from aerial photos by the National Research Institute for Earth Science and Disaster Resilience of Japan (NIED). Each LL in the inventory is composed of a scarp and a moving mass. Since landslides are prone to reactivation, it is important to evaluate the sliding-recurrence susceptibility of LLs. One possible approach to evaluate the susceptibility of LLs is slope stability analysis. A previous study found a good correlation (R ² = 0.99) between the safety factor (F _s ) and slope angle (α) of F _s  = 17.3α ^?0.843. We applied the equation to the analysis of F _s for 267 LLs in the area affected by the 2016 Kumamoto earthquake (M _j  = 7.3). The F _s was calculated for the following three cases of failure: scarps only, moving mass only, and scarps and moving mass together. Verification with the 2016 Kumamoto earthquake event shows that the most appropriate method for the evaluation of LLs is to consider the failure of scarps and moving mass together. In addition, by analyzing the relationship between the factors of slope of entire landslide and slope of scarp for LLs and comparing the results with the Aso-ohashi landslide, the largest landslide caused by the 2016 Kumamoto earthquake, we also found that morphometric analysis of LLs is useful for forecasting the travel distance of future landslides.  相似文献   

Subduction of mantle wedge peridotites: Evidence from the Higashi-akaishi ultramafic body in the Sanbagawa metamorphic belt   总被引：1，自引：0，他引：1  

Keiko  Hattori  Simon  Wallis  Masaki  Enami  Tomoyuki  Mizukami 《Island Arc》2010,19(1):192-207

The Higashi-akaishi garnet-bearing ultramafic body in the Sanbagawa metamorphic belt, Southwest Japan, represents a rare example of oceanic-type ultrahigh-pressure metamorphism. The body of 2 km × 5 km is composed mostly of anhydrous dunite with volumetrically minor lenses of clinopyroxene-rich rocks. Dunite samples contain high Ir-type platinum group elements (PGE) and Cr in bulk rocks, high Mg and Ni in olivine, and high Cr in spinel. On the other hand, clinopyroxene-rich rocks contain low concentrations of Ir-type PGE and Cr, high concentrations of fluid-mobile elements in bulk rocks, and low Ni and Mg in olivine. Clinopyroxene is diopsidic with low Al₂O₃. The compositions of bulk rocks and mineral chemistry of spinel, olivine, and clinopyroxene suggest that the olivine-dominated rocks are residual mantle peridotites after high degrees of influx partial melting, and that the clinopyroxene-rich rocks are cumulates of subduction-related melts. Thus, the Higashi-akaishi ultramafic body originated from the interior of the mantle wedge, most likely the forearc upper mantle. It was then incorporated into the Sanbagawa subduction channel by a mantle flow, and underwent high pressure metamorphism to a depth greater than 100 km. Such a strong active flow in the mantle wedge is likely facilitated by the lack of serpentinites along the interface between the slab and the overlying mantle, as it was too hot for serpentine. These unusually hot conditions and strong active mantle flow may reflect conditions in the earliest stage of development of subduction, and may have been maintained by massive upwelling and subsequent eastward flow of asthenospheric mantle in the northeastern Asian continent in Cretaceous time when the Sanbagawa belt began to form.  相似文献   

Three-dimensional non-linear soil–building interaction analysis in the lakebed zone of Mexico city during the hypothetical Guerrero earthquake     

Masahiro Iida 《地震工程与结构动力学》1998,27(12):1483-1502

The 1985 Michoacan earthquake (M=8·1) caused very severe damage to mid-rise buildings in the lakebed zone of Mexico City, which is approximately 400 km from the epicentre in the Pacific Ocean. In the present study, we perform a three-dimensional (3-D) non-linear soil–building interaction analysis for several types of low- to high-rise buildings during the hypothetical Guerrero earthquake, and try to understand the real cause of heavy damage to mid-rise buildings in the lakebed zone during the 1985 Michoacan earthquake. We make a reasonable estimation of the input earthquake motions and the local site effects. The non-linear soil-building interaction analysis explains the damage pattern observed during the 1985 earthquake, although other analyses do not. We realize that all the factors from the earthquake source to the building superstructure must be taken into account adequately. © 1998 John Wiley & Sons, Ltd.  相似文献   

Throughfall partitioning by trees     

Delphis F. Levia  Kazuki Nanko  Hiromasa Amasaki  Thomas W. Giambelluca  Norifumi Hotta  Shin'ichi Iida  Ryan G. Mudd  Michael A. Nullet  Naoki Sakai  Yoshinori Shinohara  Xinchao Sun  Masakazu Suzuki  Nobuaki Tanaka  Chatchai Tantasirin  Kozo Yamada 《水文研究》2019,33(12):1698-1708

Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and throughfall drop size, what was unknown until now is the relative proportion of each throughfall type (free throughfall, splash throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million throughfall drops, we found that the type, number, and volume of throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total throughfall volume) and slightly smaller diameter splash throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D_{50_DR}, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D_{50_DR} of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D_{50_DR} of 5.92 mm) than leafed broadleaved trees. Based on throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from <0.001 to 0.005). These findings are partly attributable to differences in canopy structure and plant surface characteristics between plant functional types and canopy state (leaf, leafless), among other factors. Hence, our results demonstrating the importance of drop‐size‐dependent partitioning between coniferous and broadleaved tree species could be useful to those requiring more detailed information on throughfall fluxes to the forest floor.  相似文献   

Influence of the Atmospheric Model on Hanle Diagnostics     

Ryohko Ishikawa  Han Uitenbroek  Motoshi Goto  Yusuke Iida  Saku Tsuneta 《Solar physics》2018,293(5):74

We clarify the uncertainty in the inferred magnetic field vector via the Hanle diagnostics of the hydrogen Lyman-\(\upalpha\) line when the stratification of the underlying atmosphere is unknown. We calculate the anisotropy of the radiation field with plane-parallel semi-empirical models under the nonlocal thermal equilibrium condition and derive linear polarization signals for all possible parameters of magnetic field vectors based on an analytical solution of the atomic polarization and Hanle effect. We find that the semi-empirical models of the inter-network region (FAL-A) and network region (FAL-F) show similar degrees of anisotropy in the radiation field, and this similarity results in an acceptable inversion error (e.g., \({\sim}\, 40~\mbox{G}\) instead of 50 G in field strength and \({\sim}\,100^{\circ}\) instead of \(90^{\circ}\) in inclination) when FAL-A and FAL-F are swapped. However, the semi-empirical models of FAL-C (averaged quiet-Sun model including both inter-network and network regions) and FAL-P (plage regions) yield an atomic polarization that deviates from all other models, which makes it difficult to precisely determine the magnetic field vector if the correct atmospheric model is not known (e.g., the inversion error is much larger than 40% of the field strength; \({>}\,70~\mbox{G}\) instead of \(50~\mbox{G}\)). These results clearly demonstrate that the choice of model atmosphere is important for Hanle diagnostics. As is well known, one way to constrain the average atmospheric stratification is to measure the center-to-limb variation of the linear polarization signals. The dependence of the center-to-limb variations on the atmospheric model is also presented in this paper.  相似文献   

Interaction between runoff – bedrock groundwater in a steep headwater catchment underlain by sedimentary bedrock fractured by gravitational deformation          下载免费PDF全文

Cristobal Padilla  Yuichi Onda  Tomoyuki Iida 《水文研究》2015,29(20):4398-4412

Recent studies have suggested the importance of the bedrock groundwater (BG) contribution in storm runoff in headwater catchments. However, few such studies have been conducted, and the study of different types of bedrock conditions is still ongoing. The role of BG in storm runoff is still poorly understood, particularly in headwater catchments underlain by relatively deep fractured bedrock. This study aims to clarify this role using hydrometric and hydrochemical observations of BG via boreholes and catchment discharge. The responses of the BG to rainfall are demonstrated to be fast and independent of the sediment cover. The BG exhibits different responses and flow paths that are largely controlled by the bedrock fracture system. The storm runoff in the studied catchment is characterized by rapid discharge response generally followed by a delayed discharge response. The peak of the delayed discharge is much faster than that observed in previous studies, and it is well correlated with the BG levels. A hydrograph separation was performed for two storm events using three end members: rainfall, shallow BG and deep BG. The results demonstrate that the delayed discharge is primarily composed of deep BG. Moreover, a significant contribution of shallow BG is observed during large precipitation events. Although we observed no physical evidence of direct contributions of BG in the catchment, the calculations presented in this study demonstrate that the BG controls the hydrological and hydrogeological response of the catchment to rainfall events. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Population genetic structure of the endangered limpet Cymbula nigra in a temperate Northern hemisphere region: influence of palaeoclimatic events?     

Free Espinosa  Tomoyuki Nakano  Jose M. Guerra‐García  Jose C. García‐Gómez 《Marine Ecology》2011,32(1):1-5

Cymbula nigra (da Costa L, 1771) is the largest limpet in Europe and it is at present considered an endangered species. Nevertheless, its biology is poorly understood and there is a lack of knowledge about population genetic structure. A total of 61 C. nigra specimens were sampled and studied for a fragment of the mitochondrial gene cytochrome c oxidase subunit I. The low genetic diversity, the absence of geographic structure, the significant values reported by measures to test for a recent population expansion and a star‐shaped phylogeny pattern are here interpreted as forming a hypothesis concerning the influence of palaeoclimatic events in the genetic pool of limpets, considering also the information available on different limpet species.  相似文献   

Selective detection of Fe and Mn species at mineral surfaces in weathered granite by conversion electron yield X-ray absorption fine structure     

Takaaki Itai  Yoshio Takahashi  Tomoya Uruga  Hajime Tanida  Atsuo Iida 《Applied Geochemistry》2008

A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-μm scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO₂ and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 × 5 μm²) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-μm scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction.  相似文献   

Alteration and mass transfer inferred from the Hirabayashi GSJ drill penetrating the Nojima Fault, Japan     

Koichiro Fujimoto  Hidemi Tanaka    Takayuki Higuchi  Naoto Tomida  Tomoyuki Ohtani  Hisao Ito 《Island Arc》2001,10(3-4):401-410

Abstract Mineralogical and geochemical studies on the fault rocks from the Nojima–Hirabayashi borehole, south-west Japan, are performed to clarify the alteration and mass transfer in the Nojima Fault Zone at shallow depths. A complete sequence from the hornblende–biotite granodiorite protolith to the fault core can be observed without serious disorganization by surface weathering. The parts deeper than 426.2 m are in the fault zone where rocks have suffered fault-related deformation and alteration. Characteristic alteration minerals in the fault zone are smectite, zeolites (laumontite, stilbite), and carbonate minerals (calcite and siderite). It is inferred that laumontite veins formed at temperatures higher than approximately 100°C during the fault activity. A reverse component in the movement of the Nojima Fault influences the distribution of zeolites. Zeolite is the main sealing mineral in relatively deep parts, whereas carbonate is the main sealing mineral at shallower depths. Several shear zones are recognized in the fault zone. Intense alteration is localized in the gouge zones. Rock chemistry changes in a different manner between different shear zones in the fault zone. The main shear zone (MSZ), which corresponds to the core of the Nojima Fault, shows increased concentration of most elements except Si, Al, Na, and K. However, a lower shear zone (LSZ-2), which is characterized by intense alteration rather than cataclastic deformation, shows a decreased concentration of most elements including Ti and Zr. A simple volume change analysis based on Ti and Zr immobility, commonly used to examine the changes in fault rock chemistry, cannot account fully for the different behaviors of Ti and Zr among the two gouge zones.  相似文献   

The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus)     

Kang  Donhyug; Mukai  Tohru; Iida  Kohji; Hwang  Doojin; Myoung  Jung-Goo 《ICES Journal of Marine Science》2005,62(4):779-789

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