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A Probabilistic Liquefaction Hazard Assessment for Urban Regions Based on Dynamics Analysis Considering Soil Uncertainties

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Journal of Earth Science 2021年第5期32卷 1129-1138页

作者： Jian Chen Hideyuki O-tani Tomohide Takeyama Satoru Oishi Muneo Hori japan Agency for marine-Earth Science and technology Yokohama 236-0001Japan RIKEN center for Computational Science Kobe 650-0047Japan Department of Civil Engineering Kobe UniversityKobe 657-8501Japaw

Earthquake induced liquefaction is one of the main geo-disasters threating urban regions, which not only causes direct damages to buildings, but also delays both real-time disaster relief actions and reconstruction activities. It is thus important to assess liquefaction hazard of urban regions effectively and efficiently for disaster prevention and mitigation. Conventional assessment approaches rely on engineering indices such as the factor of safety(FS) against liquefaction, which cannot take into account directly the uncertainties of soils. In contrast, a physics simulation-based approach, by solving soil dynamics problems coupled with excess pore water pressure(EPWP) it is possible to model the uncertainties directly via Monte Carlo simulations. In this study, we demonstrate the capability of such an approach for assessing an urban region with over 10 000 sites. The permeability parameters are assumed to follow a base-10-lognormal distribution among 100 model analyses for each site. A dynamic simulation is conducted for each model analysis to obtain the EPWP results. Based on over 1 million EPWP analysis models, we obtained a probabilistic liquefaction assessment. Empowered by high performance computing, we present for the first time a probabilistic liquefaction hazard assessment for urban regions based on dynamics analysis, which consider soil uncertainties.

关键词： liquefaction hazard assessment soil uncertainties soil dynamics analysis automatic modeling high performance computing

Light is an Important Limiting Factor for the Vertical Distribution of the Largest Extant Benthic Foraminifer Cycloclypeus carpenteri

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Journal of Earth Science 2022年第6期33卷 1460-1468页

作者： Kazuhiko Fujita Yoji Kanda Takashi Hosono Department of Physics and Earth Sciences University of the RyukyusOkinawa903-0213Japan Tropical Biosphere Research center University of the RyukyusOkinawa903-0213Japan japan Agency for marine-Earth Science and technology(JAMSTEC) Global Oceanographic Data Center(GODAC)Kanagawa236-0001Japan

Cycloclypeus carpenteri is the largest extant benthic foraminifer,dwelling in the deep euphotic zone(a water depth between 60 and 130 m)of the warm oligotrophic Indo-West *** foraminifer harbors diatom endosymbionts and the foraminifer-microalgal association acts like a *** verify that light is an important limiting factor controlling the vertical(depth)distribution of living Cycloclypeus holobionts,their physiological responses to light intensity were examined by short-term metabolic measurements and long-term *** oxygen production(OP)rates measured under different light levels using an oxygen microelectrode indicate that Cycloclypeus holobionts are daily net primary producers adapted to low light levels,with slight photoinhibition(reduced net OP rates relative to a light-saturated rate)over 100μmol photons m^(−2)s^(−1).Long-term growth increments of asexually reproduced juveniles incubated for two months at different light levels ranging from 0 to 100μmol photons m^(−2)s^(−1) show that Cycloclypeus holobionts are adapted to a low light level(∼5μmol photons m^(−2)s^(−1)),but can be acclimatized to a certain low light ranges(<50μmol photons m^(−2)s^(−1)).These experimental results confirm that light is an important environmental gradient affecting the vertical distribution of Cycloclypeus holobionts.

关键词： algal symbiosis diatom large benthic foraminifer oxygen production photosynthesis

Geochemical and Grain-Sized Implications for Provenance Variations of the Central Yellow Sea Muddy Area Since the Middle Holocene

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Journal of Ocean University of China 2020年第3期19卷 577-588页

作者： AI Lina HAN Zongzhu WU Xiao SAITO Yoshiki WANG Houjie College of marine Geosciences/Key Laboratory of Submarine Geosciences and Prospecting Techniques MOEOcean University of ChinaQingdao 266100China Laboratory of marine Geology Qingdao National Laboratory of Marine Science and TechnologyQingdao 266237China Estuary Research center Shimane UniversityMatsue 690-8504Japan Geological Survey of japan AISTTsukuba 305-8567Japan

Based on high-resolution analysis to a 280-cm long sediment core obtained from the muddy area in the central Yellow Sea, we examined the provenance of muddy sediments and discussed the changing marine sedimentary environment since the middle Holocene. The results indicated that fine-grained sediments in the muddy area were mainly derived from the Huanghe(Yellow River) and Changjiang(Yangtze River) with considerable stepwise variations during the past 6.6 kyr. The Yellow Sea Warm Current was initiated at 6 kyr when the sea level was high together with the enhanced East Asian Winter Monsoon. These in combination established the framework of shelf circulation in the Yellow Sea that began to trap the river-derived fine-grained sediments. From 4.9 kyr to 2.8 kyr, both the Kushiro Current and East Asian Monsoon were significantly weakened, reducing the delivery of Changjiang sediments to the muddy area. As a result, the sediments were mainly originated from the Huanghe. From 2.8 kyr to 1.5 kyr the continuously weakened East Asian Winter Monsoon and enhanced Yellow Sea Warm Current entrapped more fine-grain sediments. Whereas the enhanced East Asian Winter Monsoon and the human caused increase in sediment load of the Huanghe since 1.5 kyr, and direct delivery of Huanghe sediments to the Yellow Sea during 1128–1855 AD might dominated the sedimentation in the study area. The stepwise variations of the sediment provenance and composition of the Central Yellow Sea muddy sediments are of importance to understanding the formation of muddy deposit in the central Yellow Sea and the associated variations of marine environment since the middle Holocene.

关键词： sediment provenance rare earth elements grain size central Yellow Sea mud middle Holocene

Sedimentary processes and development of the Zenisu deep-sea channel, Philippine Sea

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Chinese Science Bulletin 2003年第B6期48卷 92-97页

作者： WU Shiguo~(1,2) & Sakamoto Izumi~3 1. Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China 2. Kiy Laboratory of marine Sedimentology and Environmental Geology, State Oceanic Administration. Qingdao 266061, China 3. japan Marinc Science & technology center. Yokosuka 2370061. japan Institute of Oceanology Chinese Academy of Sciences Qingdao China Key Laboratory of marine Sedimentology and Environmental Geology State Oceanic Administration Qingdao China japan marine Science & technology center Yokosuka Japan

Zenisu deep-sea channel originated from a volcanic arc region, Izu-Ogasawara Island Arc, and vanished in the Shikoku Basin of the Philippine Sea. According to the swath bathymetry, the deep-sea channel can be divided into three segments. They are Zenisu canyon, E-W fan channel and trough-axis channel. A lot of volcanic detritus were deposited in the Zenisu Trough via the deep-sea channel because it originated from volcanic arc settings. On the basis of the swath bathymetry, submersible and seismic reflection data, the deposits are characterized by turbidite and debrite deposits as those in the other major deep-sea channels. Erosion or few sediments were observed in the Zenisu canyon,whereas a lot of turbidites and debrites occurred in the E-W channel and trough axis channel. Cold seep communities,active fault and fluid flow were discovered along the lower slope of the Zenisu Ridge. Vertical sedimentary sequences in the Zenisu Trough consist of the four post-rift sequence units of the Shikoku Basin, among which Units A and B are two turbidite units. The development of Zenisu canyon is controlled by the N-S shear fault, the E-W fan channel is related to the E-W shear fault, and the trough-axis channel is related to the subsidence of central basin.

关键词：沉积过程菲律宾海海沟海洋沉积学四国盆地海洋深测术火山碎石地震数据浊流岩

High-Resolution Modeling Study of the Kuroshio Path Variations South of japan

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Advances in Atmospheric Sciences 2014年第5期31卷 1233-1244页

作者： LI Rui ZHANG Zuowei WU Lixin Physical Oceanography Laboratory/Qingdao Collaborative Innovation center of marine Science and technology Ocean University of China

A high-resolution ocean general circulation model （OGCM） is used to investigate the Kuroshio path variations south of japan. The model reproduces many important features of the Kuroshio system including its interannual bimodal variability south of japan. A decreasing trend of the spatial averaged relative vorticity is detected when the Kuroshio takes the non-large meander （NLM） path, and during the transition period from the NLM to the large meander （LM）, a sudden release of velocity shear corresponds well to the weakening of the Shikoku recirculation gyre （SRG）, which plays a key role in modulating the Kuroshio path variations. Analysis of eddy energetics indicates that baroclinic instability is mainly responsible for the formation of the LM. In addition, further analysis shows that the strength of the SRG could be largely influenced by the baroclinic Rossby wave adjustment process, forced by the wind stress curl anomalies in the North Pacific basin, based on the model investigation. It is suggested that the cyclonic disturbances might account for the weakening of the SRG, and act as a remote trigger for the baroclinic instability of the Kuroshio south of japan.

关键词： OGCM Kuroshio path variations large meander Rossby wave

Simulation of Storm Surge and Wave Due to Typhoon Isewan(5915)

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China Ocean Engineering 2015年第4期29卷 473-488页

作者： Jin-Hee YUK Kyeong Ok KIM Han Soo LEE Byung Ho CHOI Disaster Management HPC technology Research center Korea Institute of Science and Technology Information marine Radionuclide Research center Korea Institute of Ocean Science & Technology Graduate School of Science and Engineering Saitama University Department of Civil and Environmental Engineering Sungkyunkwan University

An integrally coupled wave-tide-surge model was developed and then applied to the simulation of the wave-typhoon surge for the typhoon Isewan （typhoon Vera （5915））, which is the strongest typhoon that has struck japan and caused incalculable damage. An integrally coupled tide-surge-wave model using identical and homogeneous meshes in an unstructured grid system was used to correctly resolve the physics of wave-circulation interaction in both models. All model components were validated independently. The storm surge and wave properties such as the surge height, the significant wave height, wave period and direction were reproduced reasonably under the meteorological forcing, which was reprocessed to be close to the observations. The resulting modeling system can be used extensively for the prediction of the storm surge and waves and the usual barotropic forecast.

关键词： typhoon Isewan storm surge wave tide coupled wave-tide-surge model

Variations of alkenone temperature in the Sea of japan during the last 170 ka and its paleoceanographic implications

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Chinese Science Bulletin 2014年第33期59卷 4498-4509页

作者： Yanguang Liu Jiaojie Chen Jinxia Chen Lei Xing Jianjun Zou Zhengquan Yao Key Laboratory of marine Sedimentology and Environmental Geology First Institute of Oceanography State Oceanic Administration Key Laboratory of marine Chemistry Theory and technology Ministry of Education/Qingdao Collaborative Innovation Center of Marine Science and Technology Ocean University of China

Two sediment cores, KCES1 and ODP797,which were recovered from the Sea of japan(JS), were measured for alkenone-derived sea surface temperatures(UK037-SSTs). Our results revealed that the SSTs closely follow the glacial-interglacial cycles during the last 170 ka,except in the last glacial maximum(LGM), during which the SST was higher than in the Holocene. The anomalous high temperature in the LGM is considered as an effect of the intrusion of a low salinity water mass into the JS when the sea level was almost below 130 m. On the glacialinterglacial to orbital timescale, the UK037-SSTs record in the JS correlated well with the benthic foraminiferal d18 O record and solar insolation, which suggests the dominant control of solar insolation and its related sea ice development on the SST in the JS. On the sub-orbital/millennial timescale, reduced SST corresponds to an enhanced east asian winter monsoon(EAWM) during the last glacial period(MIS3 and MIS4), indicating the dominant control of sea ice expansion due to the enhanced EAWM on the SST in the JS. In contrast, during the last interglacial period(MIS5), the SST in the JS was controlled by variations in the east Asian summer monsoon. These results highlight the key role of solar insolation and associated glacialinterglacial conditions in the variations of the SST in the JS since the last 170 ka.

关键词：海表温度日本海古海洋学烯酮末次间冰期太阳辐射 SST 末次盛冰期

Sensitivity study of subgrid scale ocean mixing under sea ice using a two-column ocean grid in climate model CESM

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Frontiers of Earth Science 2015年第4期9卷 594-604页

作者： Meibing JIN Jennifer HUTCHINGS Yusuke KAWAGUCHI International Arctic Research center University of Alaska Fairbanks AK 99775 USA College of Earth Ocean and Atmospheric Sciences Oregon State University OR 97331 USA japan Agency for marine-Earth Science and technology Yokosuka 237-0061 Japan

Brine drainage from sea ice formation plays a critical role in ocean mixing and seasonal variations of halocline in polar oceans. The horizontal scale of brine drainage and its induced convection is much smaller than a climate model grid and a model tends to produce false ocean mixing when brine drainage is averaged over a grid cell. A two-column ocean grid （TCOG） scheme was implemented in the Community Earth System Model （CESM） using coupled sea ice-ocean model setting to explicitly solve the different vertical mixing in the two sub- columns of one model grid with and without brine rejection. The fraction of grid with brine rejection was tested to be equal to the lead fraction or a small constant number in a series of sensitivity model runs forced by the same atmospheric data from 1978 to 2009. The model results were compared to observations from 29 ice tethered profilers （ITP） in the Arctic Ocean Basin from 2004 to 2009. Compared with the control run using a regular ocean grid, the TCOG simulations showed consistent reduction of model errors in salinity and mixed layer depth （MLD）. The model using a small constant fraction grid for brine rejection was found to produce the best model comparison with observations, indicating that the horizontal scale of the brine drainage is very small compared to the sea ice cover and even smaller than the lead fraction. Comparable to models using brine rejection parameterization schemes, TCOG achieved more improvements in salinity but similar in MLD.

关键词： climate model sea ice mixed-layer depth,ocean mixing brine drainage

CLIMATE PREDICTION EXPERIMENT FOR TROPICAL CYCLONE GENESIS FREQUENCY USING THE LARGE-SCALE CIRCULATION FORECAST BY A COUPLED GLOBAL CIRCULATION MODEL

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Journal of Tropical Meteorology 2014年第2期20卷 103-111页

作者：贾小龙陈丽娟罗京佳 National Climate center Laboratory for Climate Studies China Meteorological Administration Collaborative Innovation center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Climate Variation Predictability and Applicability Research Program Research Institute for Global Change Japan Agency for Marine-Earth Science and TechnologyJapan

Based on an analysis of the relationship between the tropical cyclone genesis frequency and large-scale circulation anomaly in NCEP reanalysis, large-scale atmosphere circulation information forecast by the JAMSTEC SINTEX-F coupled model is used to build a statistical model to predict the cyclogenesis frequency over the South China Sea and the western North Pacific. The SINTEX-F coupled model has relatively good prediction skill for some circulation features associated with the cyclogenesis frequency including sea level pressure, wind vertical shear, Intertropical Convergence Zone and cross-equatorial air flows. Predictors derived from these large-scale circulations have good relationships with the cyclogenesis frequency over the South China Sea and the western North Pacific. A multivariate linear regression(MLR) model is further designed using these predictors. This model shows good prediction skill with the anomaly correlation coefficient reaching, based on the cross validation, 0.71 between the observed and predicted cyclogenesis frequency. However, it also shows relatively large prediction errors in extreme tropical cyclone years(1994 and 1998, for example).

关键词： CGCM large-scale circulation tropical cyclone climate prediction