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Modeling the Contemporary Stress Field and Deformation Pattern of Eastern Mediterranean

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Journal of Earth Science 2010年第4期21卷 365-381页

作者： S K Dwivedi D Hayashi simulation tectonics laboratory Faculty of ScienceUniversity of the Ryukyus

The contemporary stress field in the earth＇s crust is important and provides insights into mechanisms that drive plate motions. In this study, elastic plane stress finite element modeling incorporating realistic rock parameters was used to calculate the stress field, displacement field, and defor- mation of the plate interactions in the eastern Mediterranean. Modeled stress data for the African- Arabian-Anatolian plate interactions with fixed European platform correlate well with observed contemporary stress indicator from the world stress map （WSM） and focal mechanism of earthquakes; while displacement field agrees qualitatively well with GPS vectors and sense of motion indicated by focal mechanisms for large crustal earthquakes （Ms〉6） and plate motion models. Modeling result shows the direction of maximum horizontal compressive stress （σHmax） toward the direction of absolute motion of these plates. Large perturbations in σHmax orientations are shown to occur in and around tectonic boundaries between those plates. It is observed that, although the African plate acts mostly as indenter, which transmits the collisional motion from the Arabian plate to the Anatolian plate, in the current situation, the far-field stress, probably from the subduction in Aegean Arc, is needed to satisfy the contemporary stress field in Anatolia.

关键词： finite element model maximum horizontal stress seismieity crustal deformation Anatolia eastern Mediterranean.

Numerical modeling of the development of southeastern Red Sea continental margin

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Earthquake Science 2009年第3期22卷 239-249页

作者： Sunil Kumar Dwivedi Daigoro Hayashi simulation tectonics laboratory Faculty of Science University of the Ryukyus

The Red Sea continental margin （RSCM） corresponds to a wide hinge zone between Red Sea and Arabian plate. This margin has been studied through geological and geophysical observations primarily in regard to the evolution of Red Sea rift. This margin is characterized by occurrence of thin sediments, significant onshore uplift, tectonic subsidence of the offshore sedimentary basin, active faulting and seismicity. Studies indicate that sedimentary sequences of the margin are deformed by faults and folds resulting from at least two phases of extension and a phase of uplift. During the two phases of extension due to regional plate stress the sequence was cut by set of extensional faults. While during the phase of uplift the sequence was deformed by folding and faulting. The present paper aims to clear the structural development of RSCM during these tectonic episodes, taken as particular tectonic event, by two-dimensional finite element modeling on plane strain condition. Elastic theology is assumed for the oceanic, continental and transitional crust along with syntectonic deposits. Stress field, shear stress and fault distribution suggests that mantle plume weakened the crust following rifting due to regional stress and developed the margin. These results are well consistent with those from present seismicity, active faulting and neotectonic studies.

关键词： Red Sea rift continental margin numerical modeling seismicity neotectonics

Numerical Modeling of Neotectonic Movements and State of Stresses in the Central Seismic Gap Region,Garhwal Himalaya

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Journal of Mountain Science 2008年第4期5卷 279-298页

作者： Ganesh Raj JOSHI Daigoro HAYASHI simulation tectonics laboratory Faculty of ScienceUniversity of the RyukyusOkinawa 903-0213Japan

This paper presents finite element modeling （FEM） to simulate the present-day stress field and crustal deformation using NE-SW structural section in the central Seismic Gap region of the Garhwal Himalaya. Our study deals with the effect of geometrical characteristics and rock layer parameters on the upper crust. Modeling results show that two types of tectonic regimes developed in the central Seismic Gap region： the geotectonics of the northern part has been controlled by regional compression, whereas southern part is characterized by regional extension. Correspondingly, thrust faults are induced in the northern part and normal faults are extensively developed in the southern front. Those evidences noticeably indicate that the compressive tectonic environment of the Himalaya becomes change into the extensional tectonic regime in its front. The computed shear stress accumulation along the northern fiat of Main Himalayan Thrust （MHT） implies that considerable amount of interseismic stress is building up along the MHT system in the Himalaya, which ultimately release through the possible future great Himalayan earthquake （M 〉 8）. The comparison between our modeled stress field, faulting pattern and horizontal shortening rate with the distribution of the microseismic events, focal mechanism solutions, active faulting and GPS data in the central Seismic Gap region shows good agreement.

关键词： Neotectonic deformation stress distribution FE modeling central Seismic Gap NW-Himalaya

Applicability of Two Newmark Models in the Assessment of Coseismic Landslide Hazard and Estimation of Slope-Failure Probability: An Example of the 2008 Wenchuan M_w 7.9 Earthquake Affected Area

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Journal of Earth Science 2019年第5期30卷 1020-1030页

作者： Siyuan Ma Chong Xu Key laboratory of Active tectonics and Volcano Institute of Geology China Earthquake Administration

This paper presents the landslide hazard assessment and slope-failure function using two Newmark displacement models regressed by regional and global station records. Taking the 2008 Wenchuan M_w 7.9 earthquake area as an example, based on the topographic and geological data of the study area, we prepared a factor-of-safety(Fs) map and a critical acceleration(ac) map, respectively. Then using these two simplified Newmark models, two displacement maps were compiled by combining the ac map and peak ground acceleration(PGA) map. By virtue of the actual landslide inventory of the Wenchuan earthquake, we constructed the slope-failure probability curves of the two Newmark models. The results show that the abilities to predict landslide occurrence of the two simplified Newmark models are largely identical, by which the assessment results can well delineate the macroscopic distribution of coseismic landslides, and most predicted landslide cells are distributed on the two sides of the Beichuan-Yingxiu fault, especially Pengguan complex rock mass in the hanging wall of this fault. The probability equations of two Newmark models are roughly the same, though the parameters vary slightly. The probability equation proposed in this paper can be applied to the Wenchuan region and other areas with similar tectonic environments.

关键词： Wenchuan earthquake seismic landslides Newmark displacement peak ground acceleration(PGA)

Photocatalytic degradation of fipronil in water by silver-modified lithium vanadium phosphate spheres under visible light irradiation

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Science China Chemistry 2015年第12期58卷 1912-1917页

作者： Lifeng Yin Lili Xie Yueping Bao Junfeng Niu State Key laboratory of Water Environment simulation

A novel visible light-driven photocatalyst, lithium vanadium phosphate sphere(LVPS), was prepared by a ball-milling method. For enhancing the photocatalytic performance, LVPS was further modified with silver(ALVPS) by a UV-light photo- reduction method. After modification, the crystalline phase of LVPS did not change, however, the UV-Vis diffuse reflectance spectrum of ALVPS was extended to 656 nm, which greatly improved its photoabsorptivity for visible light and enhanced its electron donating capacity. Under the irradiation of sunlight or visible light(>400 nm), ALVPS can rapidly remove fipronil(a persistent organic pollutant, 5 mg L?1) from aqueous solution. More than 99.7% of fipronil was removed by ALVPS after 0.5 h of irradiation, yielding a much higher removal rate than those achieved by nano-Ti O2 and Bi2O3. Photo-generated carrier trapping experiments were conducted to elucidate the photocatalytic degradation mechanism further. Hydrogen peroxide and potassium bromate suppressed the photocatalytic activity of ALVPS, while superoxide dismutase and sodium azide reinforced it, verifying that photo-generated electrons played a key role in the photochemical reaction.

关键词： lithium vanadium phosphate sphere visible light irradiation photocatalysis degradation

Define the Energy Cone Threshold and Extent of Tianchi Volcano

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Journal of Earth Science 2012年第5期23卷 768-774页

作者：万园许建东潘波 Key laboratory of Active tectonics and Volcano Institute of GeologyChina Earthquake Administration

Energy cone is a unique but characteristic slope that describes the extent of deposits left around a volcano by various fiowage phenomena, usually regarded as the boundary of pyroclastic and the source region of lahar. The energy cone value is determined as 0.07 by the energy-Hne model com- bined with the parameters of plume height and gradient, and the energy cone spread extent is defined by the numerical simulation method LAHARZ to simulate with this value based on the 1 ： 50 000 digi-tal elevation model of Tianchi （天池） Volcano, and the source region profiles in the north and south slope can prove the correctness of this threshold. This energy cone threshold and extent can be used as the reference of pyroelastic flow and lahar simulation.

关键词： energy cone energy-line pyroclastic lahar LAHARZ.

Magmatic Processes of Ashi Volcano, Western Kunlun Mountains, China

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Acta Geologica Sinica(English Edition) 2014年第2期88卷 530-543页

作者： YU Hongmei XU Jiandong ZHAO Bo SHEN Huanhuan LIN Chuanyong Key laboratory of Active tectonics and Volcano Institute of GeologyChina Earthquake Administration

The Ashikule volcanic cluster （AVC） in western Kunlun Mountains is located in a graben region at the convergence of the Altun and Kangxiwa fault zones,and consists of more than 10 main volcanoes and dozens of *** Ashi volcano lies in the central part of the volcanic *** lithology,chemical composition and texture of Ashi volcanic rocks were studied in detail,and their implication in magmatic processes was *** phenocrysts in Ashi volcanic rocks consist mainly of plagioclase and pyroxene,and the statistical results of phenocryst contents show that the rocks can be subdivided into two *** group A,the content of pyroxene phenocrysts is generally higher than that of plagioclase phenocrysts,but an inverse relation occurs in group *** TAS diagram,the compositions of both groups fall into the trachyandensite field,but they are obviously concentrated into two *** two clusters exist also in the oxide *** pyroxene phenocrysts comprise augite,bronzite and hypersthene,and their Mg# histogram shows two *** phenocrysts with reaction rim are observed in rocks of both *** An values of the core are generally 30-40,and those of the rim are 44-48,which are closer to those of euhedral *** bronzites are in equilibrium with the melt,and two sets of magma depths,i.e.,18-25 km and 13-18 km,can be estimated by using thermobarometer proposed by *** hypersthenes are not in equilibrium with the melt,and can be assigned to *** crystal size distribution （CSD） curves of plagioclase appear as kinked lines indicative of magma *** above analyses show that two magma pockets might exist beneath the Ashi *** is likely that they are connected with each *** one has more evolved and contains more acidic magma,and the other is a trachyandensite magma pocket characterized by *** magma from the upper part of the trachyandensite magma pocket might mix with more acidic magma,r

关键词： texture chemical composition crystal size distribution Ashi volcano Ashikule volcanic cluster

Preparation of earthquake-triggered landslide inventory maps using remote sensing and GIS technologies:Principles and case studies

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Geoscience Frontiers 2015年第6期6卷 825-836页

作者： Chong Xu Key laboratory of Active tectonics and Volcano Institute of GeologyChina Earthquake Administration

Inventory maps of earthquake-triggered landslides can be constructed using several methods,which are often subject to obvious differences due to lack of commonly accepted criteria or principles,To solve this problem,the author describes the principles for preparing inventory maps of earthquake-triggered landslides,focusing on varied methods and their criteria,The principles include the following key points：all landslides should be mapped as long as they can be recognized from images;both the boundary and source area position of landslides should be mapped;spatial distribution pattern of earthquake-triggered landslides should be continuous;complex landslides should be divided into distinct groups;three types of errors such as precision of the location and boundary of landslides,false positive errors,and false negative errors of earthquake-triggered landslide inventories should be controlled and reduced;and inventories of co-seismic landslides should be constructed by the visual interpretation method rather than automatic extraction of satellite images or/and aerial photographs,In addition,selection of remote sensing images and creation of landslides attribute database are also discussed in this paper,Then the author applies these principles to produce inventory maps of four events：the 12 May 2008 Wenchuan,China M_w 7.9,14 April 2010 Yushu,China M_w 6,9,12 January 2010 Haiti M_w7.0,and 2007 Aysen Fjord,Chile M_w 6.2,The results show obvious differences in comparison with previous studies by other researchers,which again attest to the necessity of establishment of unified principles for preparation of inventory maps of earthquake-triggered landslides.

关键词： Earthquake-triggered landslides Inventory Principle GIS Aerial photographs Satellite images

Constructing ECOC based on confusion matrix for multiclass learning problems

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Science China(Information Sciences) 2016年第1期59卷 135-148页

作者： Jindeng ZHOU Yun YANG Mingjie ZHANG Haibo XING Science and Technology on Complex Aviation Systems simulation laboratory

In the pattern recognition field, error-correcting output codes(ECOC) are a powerful tool to fuse any number of binary classifiers to model multiclass problems, and the research of encoding based on data is attracting more and more attention. In this paper, we are going to propose a new encoding method for constructing subclass Error-Correcting Output Codes, which was first introduced by Escalera et al. To achieve this goal, we first obtain the correlation between each pair of classes with the help of confusion matrix. Then,we select the most easily separated subclasses for classification by following Fisher's principle. At last, we were able to obtain binary partitions based on subclasses. After finishing this work, a new data-driven coding matrixSubclass ECOC will be achieved. Experimental results on University of California Irvine data sets and three kinds of high resolution range profile data sets with logistic linear classifier and support vector machine as the binary classifiers show that our approach can provide a better performance and the robustness of classification with a little longer but acceptable code length.

关键词： machine learning multiclass classification error correcting output codes subclass partition confusion matrix