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1.
A GIS (Geographic Information Systems) model was developed for Bolu Province in Turkey primarily for earthquake disaster mitigation purposes. The model served as the basis for investigating earthquake disaster vulnerability of existing settlements and identifying areas for new settlements in the Bolu Provincial Center and its counties. The set of criteria investigated in the GIS model was the following: distance from the main fault, ground acceleration, geologic basement type and terrain slope. Based on these criteria, a settlement suitability map was created, which classified the province into low, medium and high settlement suitable areas. This map was then augmented with other criteria for refinement purposes. These included the land use capability classes map of the province, the contemporary land use map derived from satellite images and the historical and contemporary earthquake occurrences within the region. Finally, the road network of the province derived from satellite images was overlaid on the settlement suitability map so that the provincial administrators could leave an evacuation zone of 200 m around the roads. This settlement suitability map is also intended to assist provincial administrators in making plans for reinforcement of existing settlements in low settlement suitable regions and opening new areas for urbanization and industrialization in high settlement suitable regions.  相似文献   

2.
王海军  孔祥冬  张勃 《冰川冻土》2016,38(5):1440-1446
以黑河山区为研究区域,利用Logic回归模型和空间分析技术对山区土地利用进行适宜性评价.以2011年土地利用现状数据作为背景值,构建气温、降水、海拔、坡度、人口密度、水系、交通网、村镇分布8种因子的评价指标体系.采用多尺度训练的方法确定适宜性评价最佳模拟尺度,对土地利用数据和评价因子进行Logic回归分析,得到评价因子对土地利用适宜性的影响程度.利用Spatial Analyst模块对对黑河山区土地适宜性进行评价,为区域土地资源合理利用提供科学参考.结果表明:(1)适宜性评价最佳尺度为210 m(ROC=0.79).(2)Logic回归结果显示,坡度、气温(βTemp=1.11)、降水对林地、草地的影响程度较高,同时距道路距离、人口密度(βPop=-0.555)对其分布也有重要影响.(3)山区土地利用适宜性排序为:Max林地=Max耕地 > Max建设用地 > Max裸地 > Max草地 > Max水域,林地与耕地最高,适宜性达到0.99.  相似文献   

3.
Land suitability evaluation is prerequisite for assessing the limitations for sustainable land use planning. We used ten site specific criteria (rainfall, texture, drainage, soil depth, slope, distance to major road, distance to nearest sugar mill, erosion hazard, risk of flooding and pH) and applied weighted multi-criteria evaluation (MCE) technique in a geographic information system (GIS) environment to evaluate land suitability for sugarcane cultivation in Bijnor district, India. The weightage of all the parameters was calculated through fuzzy analytical hierarchy process. Sugarcane suitability map was prepared integrating various parameters through weighted overlay analysis. The map was categorized as highly suitable (S1), moderately suitable (S2), marginally suitable (S3) and unsuitable (N). The analysis revealed that of the total cultivable land of the district, largest area (61%) was highly suitable followed by moderately suitable (24%), marginally suitable (7%) and unsuitable (8%) for sugarcane cultivation. Nagina, Najibabad and Bijnor sub-districts need attention of land managers and policy makers to remove the limitations and increase the suitability of sugarcane in such areas. Only 7% area was unsuitable for sugarcane cultivation. Slope, soil depth and erosion hazard were the major limiting factors making the land unsuitable for sugarcane cultivation. Therefore, these areas should be given priority for land and soil restoration efforts. The study showed effectiveness of integrated GIS and MCE approach for land suitability analysis of sugarcane.  相似文献   

4.
Recent studies have suggested the involvement of highly saline deep formation waters that modified preexisting Cu assemblages to form atacamite during supergene oxidation of Cu deposits in the Atacama region. In this report, we document the occurrence of (Ag–I) inclusions hosted by supergene chalcocite from Mantos de la Luna, an argentiferous Upper Jurassic stratabound Cu deposit in the Coastal Range of northern Chile. The presence of this unusual mineral assemblage indicates that iodargyrite precipitated from reducing iodine-rich waters, suggesting that the fluids involved in supergene enrichment of Cu deposits in the Coastal Range were more complex than previously thought. This suggests the prevalence of hyperarid conditions during the latest stages of supergene enrichment of the Mantos de la Luna Cu deposit in the Atacama region, supporting the notion that supergene enrichment processes in hyperarid areas are dynamic in nature and do not exclusively require the presence of meteoric water.  相似文献   

5.
The Asian Houbara is vulnerable species, the population of which is dwindling. Its protection must be prioritized in conservation programs. In this study, maximum entropy models were developed in four seasons to evaluate habitat suitability and factors affecting Asian Houbara in the Center and East Iran. Environmental variables used in modeling and evaluating the niche consisted of 24 environmental and climate variables for Gharetapeh hunting prohibited region and 36 environmental and climate variables for Petregan protected area. Also, seasonal overlap area was obtained using the ENM TOOLS software. The results showed that the most important factors affecting habitat suitability of the Asian Houbara in all seasons included the ratio of distance to the type of Artemisia sieberiZygophyllum eurypterum, distance to the slope 2–5%, distance to the type of Seidlitzia rosmarinus in the Gharetapeh hunting prohibited region, distance to the type of Artemisia aucheri, distance to the land passion, and distance to the dry land farming in the Petregan region. In summer and fall–winter, the most suitable habitat is Gharetapeh but is Petergan during fall–winter. There is maximum overlap in fall and winter, and the least overlap in the spring in these areas.  相似文献   

6.
In most large and fast growing urban areas, finding suitable lands for construction of landfill is one of the serious problems in environmental management. Land fill site selection process depends on different factors, regulations and constraints. Ignoring each of these parameters may cause miscalculations and lead to selection of an inappropriate landfill site which could have negative environmental, economical, and ecological impacts. Therefore, this process must be accomplished by taking into account all of the related criterions and variables. In this study, landfill site selection is performed by combining geographic information system (GIS) and analytical hierarchy process (AHP) in Hamedan province, west of Iran. In relation to landfill site selection, ten different criteria including Geology, surface water, aquifer, land use, elevation, slope, and distance to main roads, residential areas, faults and sinkholes were investigated. Using AHP each criterion was weighted, then geographic information system (Arc GIS 9.3 software) was used to manipulate and present spatial data. Finally, suitability map was prepared by overlay analyses and most suitable and suitable areas were identified and checked in field. The results indicate that 60.4 % of the area in the Hamedan province (11,631 km2) is unsuitable, 33 % (6,257.7 km2) moderately suitable and 6.6 % (1,344 km2) most suitable for construction of landfill.  相似文献   

7.
本文选择东南沿海地区具有典型降雨型滑坡的淳安县作为研究区,在完成全县地质灾害详细调查的基础上,选取高程、坡度、坡向、曲率、工程地质岩组、距断层距离、距道路距离、土地利用和植被等9个滑坡影响因子,利用GIS技术与确定性系数分析方法,对这9个影响因子开展敏感性分析。研究结果表明:(1) 寒武、震旦、石炭和白垩系是滑坡易发地层,侵入岩组、紫红色砂岩、碳酸盐岩夹碎屑岩、碳酸盐岩为主的岩组是滑坡高敏感性岩组;滑坡受断层影响总体上随着距离断层由近及远逐渐降低;(2) 坡度范围10°~35°是滑坡的易发坡度,30°~35°滑坡数量达到峰值;SE和S等朝南坡向是滑坡最易发坡向;高程范围为100~200m是滑坡最易发区间;凹坡最易发生滑坡,而凸坡则滑坡敏感性最差;非林地、茶叶、竹林和经济林等是滑坡高敏感植被类型;(3) 住宅用地、耕地、园地等与人类活动密切相关的用地类型是滑坡易发地类;距道路距离因子对滑坡敏感性低,相关性不明显。上述各滑坡影响因子最利于滑坡发生的数值区间确定,将为研究区进一步开展降雨型滑坡区域易发性评价及预测奠定基础。  相似文献   

8.
The Central Andean gravity high, a relic of an old subduction complex?   总被引:1,自引:0,他引:1  
The Central Andean gravity high (CAGH) is a positive anomaly in isostatic residual gravity with its center located at the western flank of the Central Andes at about 24°S. The gravity was analyzed by various methods to draw quantitative conclusions about the sources of this anomaly and their process of formation. Methods include the analysis of the gravity gradients, power spectrum, wavelength filters, and Euler deconvolution.Numerical investigations of gravity field in the area of the CAGH indicate the presence of a dense body of nearly 400 km length and about 100–140 km width, that masses lie at varying depths between 10 and 38 km. A correlation between the location of the residual anomalies and the topographic lows in the area between the Salars de Atacama and Pipanaco is observed, which indicates the strong influence of the anomalous-causing rocks of the CAGH within the formation process of the Andean orogen. An influence of these causing bodies of rock on the trend of Holocene volcanic arc is likely. Genesis of the anomalous dense formations of rock could be traced back to Ordovician–Silurian time when a pre-Andean subduction zone is postulated in the region of northern Chile with its corresponding volcanic arc in the region of the CAGH.

Zusammenfassung

El campo de gravedad alto de los Andes Centrales (CAGH) consiste en una pronunciada anomalía positiva de la gravedad isostática, cuyo centro se encuentra en el borde oeste de los Andes Centrales a los 24°S. En este estudio se analizó el campo de gravedad mediante distintos métodos, de manera de poder establecer conclusiones cuantitativas sobre el causante de esta anomalía y el proceso de formación de este causante.La investigación numérica de las anomalías gravimétricas del CAGH indica la presencia de un cuerpo de alta densidad con aproximadamente 400 km de largo y 100–140 km de ancho, que se encuentra a profundidades variables entre 10 y 38 km. Se observa una correlación entre la posición de la anomalía residual y los bajos topográficos en los areas de Salares de Atacama, Arizaro, Antofalla y Pipanaco, la cual indica una fuerte influencia de rocas productoras de la anomalía en el CAGH, dentro del proceso de formación del orógeno andino. Es probable que estos cuerpos de rocas causantes de la anomalía tengan incluso influencia en el alineamiento del arco volcánico holocénico. La generación de cuerpos de rocas con una densidad anómala puede remontarse al Ordovícico–Silúrico, tiempo para el que postula una subducción pre-Andina en la región del norte de Chile y que corresponde con el arco volcánico en la región del CAGH.  相似文献   

9.
The Central Andes host some of the world’s largest porphyry copper deposits. The economic viability of these deposits is dependent on the size and quality of their supergene enrichment blanket. Published models that have strongly influenced exploration policy suggest that supergene enrichment ceased at 14 Ma due to an increase in aridity. Here we discuss these models using published geochronological, geomorphological and geological data. Geochronological data indicate that supergene oxidation and enrichment has been active between 17 and 27°S across the forearc of northern Chile and southern Peru from 44 to 6 Ma, and on the Bolivian Altiplano and Eastern Cordillera of Argentina from 11 Ma to present. There is evidence for cessation at 20, 14 and 6 Ma. However, a major problem is that as more geochronological data become available the age ranges and periods of enrichment increase. This suggests that the full spectrum of enrichment ages may not have been sampled. The relationship between supergene enrichment and the age of regional pediplain surface development is not well constrained. Only in two areas have surfaces related to enrichment been directly dated (southern Peru and south of 26°S in Chile) and suggest formation post 14 Ma. Sedimentological data indicate that a fluctuating arid/semi-arid climate prevailed across the Atacama Desert until between 4 and 3 Ma, climatic conditions that are thought to be favourable for supergene enrichment. The balance between uplift, erosion, burial and sufficient water supply to promote enrichment is complex. This suggests that a simple model for controlling supergene enrichment is unlikely to be widely applicable in northern Chile. General models that involve climatic desiccation at 14 Ma related to rainshadow development and/or the presence of an ancestral cold-upwelling Humboldt Current are not supported by the available geological evidence. The integration of disparate sedimentological, geomorphological and supergene age data will be required to fully understand the controls on and distribution of supergene oxidation and enrichment in the Central Andes.  相似文献   

10.
Groundwater is a valuable natural resource for drinking, domestic, livestock use, and irrigation, especially in arid and semi-arid regions like the Garmiyan belt in Kurdistan region. The Awaspi watershed is located 50 km east of Kirkuk city, south Kurdistan, Iraq; and covers an area of 2146 km2. The paper presents result of a study aimed at: (1) mapping and preparing thematic layers of factors that control groundwater recharge areas, and (2) determination of sites suitable for groundwater recharge. We used available data such as geological map, groundwater depth map, digital elevation model (DEM), Landsat 8 imagery, and tropical rainfall measuring mission (TRMM) data for this study. These data, supplemented by slope features, lithology, land use land cover, rainfall, groundwater depth, drainage density, landform, lineament density, elevation and topographic position index, were utilized to create thematic maps to identify suitable areas of groundwater recharge, using GIS and remote sensing techniques. Analytic hierarchy process (AHP) was applied to weight, rank, and reclassify these maps in the ArcGIS 10.3 environment, to determine the suitable sites for groundwater recharge within the Awaspi watershed. Fifty-five percent of the total area of the watershed was found to be suitable for groundwater recharge; whereas 45% of the area was determined to have poor suitability for groundwater recharge, but can be used for surface water harvesting.  相似文献   

11.
Major bodies of fresh water are extremely scarce in the dry Atacama region. Unlike the Salar de Atacama, which has no outlet, the Salar de Punta Negra (24$ 35′ S, 3000 m elevation) used to spill north into the Atacama drainage. Archaeological survey of the beaches and spillway above today's salar indicates late-glacial human use of the 800 km2 lake and environs under a contrasting climate regime. The histories and water budgets of the Pleistocene lakes of the south-central Andes are not well understood, but archaeological data can be interpreted to support (1) hypotheses that would bring westerly storm tracks and winter rain further north 14,000 to 10,000 B.P., especially if accompanied by increasing warmth for part of the period, and/or (2) theories of orbital variation, increased summer insolation, and strengthened monsoons that would provide generally increased rainfall at the Tropics 10,000 to 9000 B.P. Archaeological, paleoclimatological, and geomorphological studies come together to show how this large lake could be a focus of human activity from the time of first settlement of the Atacama region.  相似文献   

12.
Landfill site selection by using geographic information systems   总被引:3,自引:3,他引:3  
One of the serious and growing potential problems in most large urban areas is the shortage of land for waste disposal. Although there are some efforts to reduce and recover the waste, disposal in landfills is still the most common method for waste destination. An inappropriate landfill site may have negative environmental, economic and ecological impacts. Therefore, it should be selected carefully by considering both regulations and constraints on other sources. In this study, candidate sites for an appropriate landfill area in the vicinity of Ankara are determined by using the integration of geographic information systems and multicriteria decision analysis (MCDA). For this purpose, 16 input map layers including topography, settlements (urban centers and villages), roads (Highway E90 and village roads), railways, airport, wetlands, infrastructures (pipelines and power lines), slope, geology, land use, floodplains, aquifers and surface water are prepared and two different MCDA methods (simple additive weighting and analytic hierarchy process) are implemented to a geographical information system. Comparison of the maps produced by these two different methods shows that both methods yield conformable results. Field checks also confirm that the candidate sites agree well with the selected criteria.  相似文献   

13.
To understand the mechanism of the earth structure damage, a wide range of investigations along roads in seismic hazard areas have been carried out after the 2008 Wenchuan earthquake. In this paper, the results from 41 roads investigated are presented, and the 41 roads are located in 7–11 intensity zones and consist of rural/county roads, province roads and state roads in Sichuan province. According to the investigation, the types of damaged slopes and retaining walls are classified and statistical analyses are performed. In the statistical analyses, various impact factors to seismic slope and retaining wall damage were studied, such as slope inclination, height of slope and retaining wall, site conditions, and seismic intensity. In addition, some relationships were developed, including the quantity of damaged slopes with slope inclination and height, the angle between route and fault rupture directions, and site conditions. Finally, some reasonable suggestions are put forward on the designs and constructions of slopes and retaining walls when they are subject to seismic activity.  相似文献   

14.
The present study is aimed at producing landslide susceptibility map of a landslide-prone area (Anfu County, China) by using evidential belief function (EBF), frequency ratio (FR) and Mahalanobis distance (MD) models. To this aim, 302 landslides were mapped based on earlier reports and aerial photographs, as well as, carrying out several field surveys. The landslide inventory was randomly split into a training dataset (70%; 212landslides) for training the models and the remaining (30%; 90 landslides) was cast off for validation purpose. A total of sixteen geo-environmental conditioning factors were considered as inputs to the models: slope degree, slope aspect, plan curvature, profile curvature, the new topo-hydrological factor termed height above the nearest drainage (HAND), average annual rainfall, altitude, distance from rivers, distance from roads, distance from faults, lithology, normalized difference vegetation index (NDVI), sediment transport index (STI), stream power index (SPI), soil texture, and land use/cover. The validation of susceptibility maps was evaluated using the area under the receiver operating characteristic curve (AUROC). As a results, the FR outperformed other models with an AUROC of 84.98%, followed by EBF (78.63%) and MD (78.50%) models. The percentage of susceptibility classes for each model revealed that MD model managed to build a compendious map focused at highly susceptible areas (high and very high classes) with an overall area of approximately 17%, followed by FR (22.76%) and EBF (31%). The premier model (FR) attested that the five factors mostly influenced the landslide occurrence in the area: NDVI, soil texture, slope degree, altitude, and HAND. Interestingly, HAND could manifest clearer pattern with regard to landslide occurrence compared to other topo-hydrological factors such as SPI, STI, and distance to rivers. Lastly, it can be conceived that the susceptibility of the area to landsliding is more subjected to a complex environmental set of factors rather than anthropological ones (residential areas and distance to roads). This upshot can make a platform for further pragmatic measures regarding hazard-planning actions.  相似文献   

15.
The Central Patagonian Andes is a particular segment of the Andean Cordillera that has been subjected to the subduction of two spreading ridges during Eocene and Neogene times. In order to understand the Cenozoic geologic evolution of the Central Patagonian Andes, we carried out geochronologic(U-Pb and40Ar/39Ar), provenance, stratigraphic, sedimentologic, and geochemical studies on the sedimentary and volcanic Cenozoic deposits that crop out in the Meseta Guadal and Chile Chico areas(~47°S). Our data indicate the presence of a nearly complete Cenozoic record, which refutes previous interpretations of a hiatus during the middle Eocene-late Oligocene in the Central Patagonian Andes. Our study suggests that the fluvial strata of the Ligorio Marquez Formation and the flood basalts of the Basaltos Inferiores de la Meseta Chile Chico Formation were deposited in an extensional setting related to the subduction of the Aluk-Farallon spreading ridge during the late Paleocene-Eocene. Geochemical data on volcanic rocks interbedded with fluvial strata of the San Jose Formation suggest that this unit was deposited in an extensional setting during the middle Eocene to late Oligocene. Progressive crustal thinning allowed the transgression of marine waters of Atlantic origin and deposition of the upper Oligocene-lower Miocene Guadal Formation. The fluvial synorogenic strata of the Santa Cruz Formation were deposited as a consequence of an important phase of compressive deformation and Andean uplift during the early-middle Miocene. Finally, alkali flood basalts of the late middle to late Miocene Basaltos Superiores de la Meseta Chile Chico Formation were extruded in the area in response to the suduction of the Chile Ridge under an extensional regime. Our studies indicate that the tectonic evolution of the Central Patagonian Andes is similar to that of the North Patagonian Andes and appears to differ from that of the Southern Patagonian Andes, which is thought to have been the subject of continuous compressive deformation since the late Early Cretaceous.  相似文献   

16.
Plant macrofossils from 33 rodent middens sampled at three sites between 2910 and 3150 m elevation in the main canyon of the Río Salado, northern Chile, yield a unique record of vegetation and climate over the past 22,000 cal yr BP. Presence of low-elevation Prepuna taxa throughout the record suggests that mean annual temperature never cooled by more than 5°C and may have been near-modern at 16,270 cal yr BP. Displacements in the lower limits of Andean steppe and Puna taxa indicate that mean annual rainfall was twice modern at 17,520–16,270 cal yr BP. This pluvial event coincides with infilling of paleolake Tauca on the Bolivian Altiplano, increased ENSO activity inferred from a marine core near Lima, abrupt deglaciation in southern Chile, and Heinrich Event 1. Moderate to large increases in precipitation also occurred at 11,770–9550 (Central Atacama Pluvial Event), 7330–6720, 3490–2320 and at 800 cal yr BP. Desiccation occurred at 14,180, 8910–8640, and 4865 cal yr BP. Compared to other midden sites in the region, early Holocene desiccation seems to have happened progressively earlier farther south. Emerging trends from the cumulative midden record in the central Atacama agree at millennial timescales with improved paleolake chronologies for the Bolivian Altiplano, implying common forcing through changes in equatorial Pacific sea-surface temperature gradients.  相似文献   

17.
滑坡空间易发性分析有助于开展滑坡防灾减灾工作,训练有效的滑坡预测模型在其中扮演重要角色.以三峡库区湖北段为研究区,选取高程、坡度、斜坡结构、土地利用类型、岩土体类型、断裂距离、路网距离、河网距离、以及归一化植被指数这9个影响因子建立滑坡空间数据库,采用集成学习中的随机森林算法进行滑坡易发性评价.结果显示,随机森林抽样训练的方式有利于确定较优的训练参数,保证随机森林在不过拟合的情况下取得满意的拟合能力和泛化能力.随机森林绘制的滑坡易发性分级图显示出合理的空间分布,其中73.35%的滑坡分布在较高和极高级别区域.而巴东县北部、秭归县中部以及夷陵区南部等区域显示出较高的易发性级别.性能评估及易发性统计结果均表明随机森林是一种出色的算法,在滑坡空间预测领域具有较好的适用性.   相似文献   

18.
The regional patterns of texture and composition of modern continental slope and pelagic sediments off Chile between 25°S and 43°S reflect the latitudinal segmentation of geological, morphological, and climatic features of the continental hinterland. Grain-size characteristics are controlled by the grain-size of source rocks, the weathering regime, and mode of sediment input (eolian off northern Chile vs fluvial further south). Bulk-mineral assemblages reveal a low grade of maturity. Regional variations are governed by the source-rock composition of the different geological terranes and the relative source-rock contribution of the Coastal Range and Andes, as controlled by the continental hydrology. The relative abundance of clay minerals is also predominantly influenced by the source-rock composition and partly by continental smectite neoformation. Latitudinal variations of illite crystallinities along the Chilean continental slope (and west of the Peru–Chile trench) clearly reflect modifications of the weathering regime which correspond to the strong climatic zonation of Chile.  相似文献   

19.
The main goal of this study was to investigate the application of the weights-of-evidence and certainty factor approaches for producing landslide susceptibility maps of a landslide-prone area (Haraz) in Iran. For this purpose, the input layers of the landslide conditioning factors were prepared in the first stage. The landslide conditioning factors considered for the study area were slope gradient, slope aspect, altitude, lithology, land use, distance from streams, distance from roads, distance from faults, topographic wetness index, stream power index, stream transport index and plan curvature. For validation of the produced landslide susceptibility maps, the results of the analyses were compared with the field-verified landslide locations. Additionally, the receiver operating characteristic curves for all the landslide susceptibility models were constructed and the areas under the curves were calculated. The landslide locations were used to validate results of the landslide susceptibility maps. The verification results showed that the weights-of-evidence model (79.87%) performed better than certainty factor (72.02%) model with a standard error of 0.0663 and 0.0756, respectively. According to the results of the area under curve evaluation, the map produced by weights-of-evidence exhibits satisfactory properties.  相似文献   

20.
2010年1月12日海地MW 7.0级地震触发了大量的滑坡。我们基于GIS与遥感技术构建了3类详细完备的海地地震滑坡编录图,分别为单体滑坡面分布数据,滑坡中心点位置数据与滑坡后壁点位置数据。结果表明海地地震触发了30828处滑坡,这些滑坡大致分布在一个面积为3192.85km2的区域内,滑坡覆盖面积为15.736km2。基于滑坡中心点密度(LCND)、滑坡后壁点密度(LTND)、滑坡面积百分比(LAP)与滑坡剥蚀厚度(LET)这4个衡量指标,使用统计分析方法,分析了海地地震滑坡及其剥蚀厚度与地震参数、地形参数、公路参数的关系。分析结果表明滑坡与坡度、地震动峰值加速度(PGA)存在大致的正相关关系; 与距离恩里基约芭蕉园断裂、距离水系存在大致的负相关关系; 滑坡沿着恩里基约芭蕉园断裂距离的统计结果表明,震中以西距离震中22~26km与8~12km的区域,与震中以东距离震中6~18km的区域是地震滑坡易发区域; 斜坡曲率值越接近0,也就是坡面较平的斜坡越不容易在地震条件下发生滑动; LCND、LTND、LAP与LET高值对应的高程区间为200~1200m; 滑坡发生的优势坡向为E方向; 滑坡的发生与距离震中、距离公路没有太明确的关系。  相似文献   

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