一种初始涡旋重定位方法及热带气旋路径数值模拟试验   总被引：6，自引：3，他引：3  

袁金南  宋丽莉  黄燕燕  陈子通  刘春霞  丁伟钰 《热带气象学报》2010,26(3):257-263

采用平滑滤波和柱形滤波技术,从背景场中分离出初始涡旋环流和大尺度环境场,然后把分离出的涡旋环流进行平移和再植入到观测位置,最终得到一种初始涡旋重定位方法。针对2006—2007年7个热带气旋共23个时次,采用背景场直接加入热带气旋bogus模型和背景场进行初始涡旋重定位后加入热带气旋bogus模型2种方案,分别进行了对比模拟试验。结果表明:对背景场进行初始涡旋重定位后加入热带气旋bogus模型的方案模拟的24和48小时热带气旋路径平均误差都相对较小,初始涡旋重定位方法可以减小热带气旋模式因热带气旋初始位置偏差而引起的误差,有助于提高热带气旋模式的路径预报水平,有较好的业务应用前景。  相似文献   

2015年河北滦县震群发震机理分析   总被引：10，自引：1，他引：9       下载免费PDF全文

谭毅培  邓莉  曹井泉  单连君 《地球物理学报》2016,59(11):4113-4125

震群发震机理研究是近年来地震学研究的热点之一,其中基于观测现象对不同发震机理模型的分析和讨论是研究焦点.本文以2015年河北滦县震群为研究对象,首先通过模板匹配方法检测震群活动期间目录遗漏地震事件,得到更为完整的地震目录.再通过波形互相关震相检测技术标定地震事件在记录台站的震相到时,依据标定的震相到时,利用双差定位方法对震群进行精定位,基于地震精定位结果分析震群的震中扩展特征.最后通过波形互相关系数和破裂面重合程度检测震群中是否存在重复地震活动.通过计算共检测到目录遗漏地震事件103个.地震精定位结果显示发震构造为北东向断层,震中扩展表现出迁移速率先快后慢的两阶段线性扩展特征.震群活动期间共检测到两组重复地震活动,其中第一组发生在震中扩展的第一阶段,第二组发生在震中扩展的第二阶段.在三种常见的震群发震机理模型——级联触发模型、断层慢滑动模型和流体侵入模型中,断层慢滑动模型能够解释我们观测到的重复地震活动和震中线性扩展现象,因此认为此次滦县震群活动可能伴随断层的慢滑动,断层慢滑动可能对滦县震群的触发和持续活动起到一定作用.  相似文献   

瑞昌-阳新4.6级地震序列震源位置及震源机制研究     

董非非  邓辉  胡睿  李正 《大地测量与地球动力学》2016,36(12):1047-1051

基于江西省及邻区数字地震台网资料,对瑞昌-阳新4.6级地震序列进行重新定位,反演该序列里较大地震的震源机制解,探讨该地震序列的空间分布特征以及发震构造,并对震区内两次中强地震之间的关系进行讨论。结果表明,瑞昌-阳新4.6级地震序列走向约为NE60°,主震发震构造为郯庐断裂带分支垄塘-皮家山隐伏断裂带;瑞昌-阳新4.6级地震序列与九江-瑞昌5.7级地震序列时空分布特点密切相关。  相似文献   

Book Reviews     

《Singapore journal of tropical geography》2002,23(1):123-130

Book Reviewed:
Mike Davis, Late Victorian Holocausts: El Niño Famines and the Making of the Third World
Hans-Dieter Evers and Rüdiger Korff, Southeast Asian Urbanism: The Meaning and Power of Social Space
Peter Boomgaard and Ian Brown (eds.), Weathering the Storm: The Economies of Southeast Asia in the 1930s Depression
Lisa Law, Sex Work in Southeast Asia: The Place of Desire in a Time of AIDS  相似文献   

航片判译茅台赤水河沿岸的滑坡     

乔建平 《贵州地质》1992,9(1):53-58

作者采用1:1.5万黑白航片判译茅台赤水沿岸滑坡共41个；其中体积大于1．5万m^3的滑坡16个，判译准确率达88％，漏、错判2个；体积大于10万m^3的滑坡12个，判译准确率达94％，漏判1个；体积大于30万m^3的滑坡6个，判译准确率达100％；判译验证不稳定蠕动体2个，体积的大于或等于5万m^3。对区内滑坡的发育规律及破坏模式作了分析研究。  相似文献   

LIMITATION OF CURRENT TECTONIC DEFORMATION MODES IN THE WESTERN MARGIN OF ORDOS BASED ON SEISMIC ACTIVITY CHARACTERISTICS          下载免费PDF全文

ZHAN Hui-li  ZHANG Dong-li  HE Xiao-hui  SHEN Xu-zhang  ZHENG Wen-jun  LI Zhi-gang 《地震地质》1979,42(2):346-365

Due to the interaction between the Tibetan plateau, the Alxa block and the Ordos block, the western margin of Ordos(33.5°~39°N, 104°~108°E)has complex tectonic features and deformation patterns with strong tectonic activities and active faults. Active faults with different strikes and characteristics have been developed, including the Haiyuan Fault, the Xiangshan-Tianjingshan Fault, the Liupanshan Fault, the Yunwushan Fault, the Yantongshan Fault, the eastern Luoshan Fault, the Sanguankou-Niushoushan Fault, the Yellow River Fault, the west Qinling Fault, and the Xiaoguanshan Fault. In this study, 7 845 earthquakes(M≥1.0)from January 1st, 1990 to June 30th, 2018 were relocated using the double-difference location algorithm, and finally, we got valid locations for 4 417 earthquakes. Meanwhile, we determined focal mechanism solutions for 54 earthquakes(M≥3.5)from February 28th, 2009 to September 2nd, 2017 by the Cut and Paste(CAP)method and collected 15 focal mechanism solutions from previous studies. The spatial distribution law of the earthquake, the main active fault geometry and the regional tectonic stress field characteristics are studied comprehensively. We found that the earthquakes are more spatially concentrated after the relocation, and the epicenters of larger earthquakes(M≥3.5) are located at the edge of main active faults. The average hypocenter depth is about 8km and the seismogenic layer ranges from 0 to 20km. The spatial distributions and geometry structures of the faults and the regional deformation feature are clearly mapped with the relocated earthquakes and vertical profiles. The complex focal mechanism solutions indicate that the arc-shaped tectonic belt consisting of Haiyuan Fault, Xiangshan-Tianjingshan Fault and Yantongshan Fault is dominated by compression and torsion; the Yellow River Fault is mainly by stretching; the west Qinling Fault is characterized by shear and compression. The structural properties of the fault structure are dominated by strike-slip and thrust, with a larger strike-slip component. The near-north-south Yellow River Fault is characterized by high angle NW dipping and normal fault motion. Based on small earthquake relocation and focal mechanism solution results, and in combination with published active structures and geophysical data in the study area, it is confirmed that the western margin of Ordos is affected by the three blocks of the Tibetan plateau, the Alax and the Ordos, presenting different tectonic deformation modes, and there are also obvious differences in motion among the secondary blocks between the active faults. The area south of the Xiangshan-Tianjingshan Fault has moved southeastward since the early Quaternary; the Yinchuan Basin and the block in the eastern margin of the Yellow River Fault move toward the SE direction.  相似文献   

STUDY ON SOURCE PARAMETERS OF THE 8 AUGUST 2017 M7.0 JIUZHAIGOU EARTHQUAKE AND ITS AFTERSHOCKS,NORTHERN SICHUAN          下载免费PDF全文

WU Wei-wei  WEI Ya-ling  LONG Feng  LIANG Ming-jian  CHEN Xue-fen  SUN Wei  ZHAO Jing 《地震地质》1979,42(2):492-512

On August 8, 2017, a strong earthquake of M7.0 occurred in Jiuzhaigou County, Aba Prefecture, northern Sichuan. The earthquake occurred on a branch fault at the southern end of the eastern section of the East Kunlun fault zone. In the northwest of the aftershock area is the Maqu-Maqin seismic gap, which is in a locking state under high stress. Destructive earthquakes are frequent along the southeast direction of the aftershocks area. In Songpan-Pingwu area, only 50~80km away from the Jiuzhaigou earthquake, two M7.2 earthquakes and one M6.7 earthquake occurred from August 16 to 23, 1976. Therefore, the Jiuzhaigou earthquake was an earthquake that occurred at the transition part between the historical earthquake fracture gap and the neotectonic active area. Compared with other M7.0 earthquakes, there are few moderate-strong aftershocks following this Jiuzhaigou earthquake, and the maximum magnitude of aftershocks is much smaller than the main shock. There is no surface rupture zone discovered corresponding to the M7.0 earthquake. In order to understand the feature of source structure and the tectonic environment of the source region, we calculate the parameters of the initial earthquake catalogue by Loc3D based on the digital waveform data recorded by Sichuan seismic network and seismic phase data collected by the China Earthquake Networks Center. Smaller events in the sequence are relocated using double-difference algorithm; source mechanism solutions and centroid depths of 29 earthquakes with M_L≥3.4 are obtained by CAP method. Moreover, the source spectrum of 186 earthquakes with 2.0≤M_L≤5.5 is restored and the spatial distribution of source stress drop along faults is obtained. According to the relocations and focal mechanism results, the Jiuzhaigou M7.0 earthquake is a high-angle left-lateral strike-slip event. The earthquake sequence mainly extends along the NW-SE direction, with the dominant focal depth of 4~18km. There are few shallow earthquakes and few earthquakes with depth greater than 20km. The relocation results show that the distribution of aftershocks is bounded by the M7.0 main shock, which shows obvious segmental characteristics in space, and the aftershock area is divided into NW segment and SE segment. The NW segment is about 16km long and 12km wide, with scattered and less earthquakes, the dominant focal depth is 4~12km, the source stress drop is large, and the type of focal mechanism is complicated. The SE segment is about 20km long and 8km wide, with concentrated earthquakes, the dominant depth is 4~12km, most moderate-strong earthquakes occurred in the depth between 11~14km. Aftershock activity extends eastward from the start point of the M7.0 main earthquake. The middle-late-stage aftershocks are released intensively on this segment, most of them are strike-slip earthquakes. The stress drop of the aftershock sequence gradually decreases with time. Principal stress axis distribution also shows segmentation characteristics. On the NW segment, the dominant azimuth of P axis is about 91.39°, the average elevation angle is about 20.80°, the dominant azimuth of T axis is NE-SW, and the average elevation angle is about 58.44°. On the SE segment, the dominant azimuth of P axis is about 103.66°, the average elevation angle is about 19.03°, the dominant azimuth of T axis is NNE-SSW, and the average elevation angle is about 15.44°. According to the fault profile inferred from the focal mechanism solution, the main controlling structure in the source area is in NW-SE direction, which may be a concealed fault or the north extension of Huya Fault. The northwest end of the fault is limited to the horsetail structure at the east end of the East Kunlun Fault, and the SE extension requires clear seismic geological evidence. The dip angle of the NW segment of the seismogenic fault is about 65°, which may be a reverse fault striking NNW and dipping NE. According to the basic characteristics of inverse fault ruptures, the rupture often extends short along the strike, the rupture length is often disproportionate to the magnitude of the earthquake, and it is not easy to form a rupture zone on the surface. The dip angle of the SE segment of the seismogenic fault is about 82°, which may be a strike-slip fault that strikes NW and dips SW. The fault plane solution shows significant change on the north and south sides of the main earthquake, and turns gradually from compressional thrust to strike-slip movement, with a certain degree of rotation.  相似文献   

Residential relocation under market-oriented redevelopment: the process and outcomes in urban China   总被引：3，自引：0，他引：3  

Fulong Wu 《Geoforum》2004,35(4):453-470

Residential displacement by urban regeneration in western economies and forced relocation in the Third World countries are contentious issues. This paper, based on a household survey in Shanghai, examines the process and outcomes of residential relocation under market-oriented urban redevelopment in China. The results show that commodification of the socialist tenancy right helped to initiate large-scale urban redevelopment. First, there has been a complicated process of negotiation during residential relocation, involving residents, development companies, and government agencies. The de facto right of public housing tenants is considered by a pragmatic attitude in urban redevelopment in the early years. Second, residential relocation is accompanied by the changes in housing tenure, housing conditions, and the improved built form of planned residential districts. Nevertheless, the social conflict has become intensified recently because the deepening of commodification began to favour property developers by constraining the compensation standard for relocated households.  相似文献   

Isolated deep earthquakes beneath the North Island of New Zealand     

T. Boddington  C. J. Parkin  D. Gubbins 《Geophysical Journal International》2004,158(3):972-982

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New constraints on seismicity in the Wellington region of New Zealand from relocated earthquake hypocentres   总被引：1，自引：0，他引：1  

Wen-xuan Du  Clifford H. Thurber  Martin Reyners  Donna Eberhart-Phillips  Haijiang Zhang 《Geophysical Journal International》2004,158(3):1088-1102

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