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利用双差定位法对三峡数字遥测地震台网记录到的秭归附近地区2008—2011年的73个M≥1.0地震重新进行定位,得到58个定位结果。结果显示,精定位后在减小残差、控制震中分布和震源深度方面均有较大改进。震中平均误差为:南北向0.42 km,东西向0.63 km,垂直向1.53 km。精定位后显示,74%的地震事件深度分布在7 km左右,平均深度6.8 km。结合秭归附近地区地震活动情况,分析了该地区的地震趋势。 相似文献
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豫北及邻区地震双差法重新定位研究 总被引：3，自引：0，他引：3
利用双差地震定位法对豫北及邻区1985—2008年的787次地震进行重新定位,得到了497次地震定位结果。结果显示：重新定位后震中呈条带状丛集分布,部分地区地震向构造带趋近;震源深度主要分布在上地壳和中地壳内,平均深度13.3 km,10～20 km为多震层深度范围。 相似文献
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北京防震历史经验与汶川地震灾后城镇选址重建 总被引：5，自引：2，他引：3
5.12汶川8.0级地震使灾区蒙受了巨大的生命和财产损失,地震造成的灾害与灾区地质构造有极强的空间相关性。灾区地震历史的分析结果表明,该区域地震格局有明显的时空特征,重灾区灾后重建城镇选址宜多学科联合谨慎规划。康熙18年(1679年)的北京平谷-三河8.0级地震与5.12汶川地震惨烈程度相近,北京地质构造研究与地震时空格局分析具有重大的现实意义,北京城市发展中的防震规划历史经验值得5.12地震灾区在重建与今后发展中借鉴。 相似文献
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双差定位法在三峡库区地震定位中的应用 总被引：12，自引：5，他引：7
基于三峡地震台网2003年5月19日至2005年8月的地震记录资料,用双差定位法对发生于三峡库区(30.5°～31.5°N、109.5°～111.5°E)的1676次地震进行了重新定位。重新定位后的地震最大偏移量为10.93km,最小为0.08km,平均偏移量为1.87km,平均震源深度为6.59km。 相似文献
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基于四川防震减灾信息网以及中国地震台网中心、中国地震信息网、国家地震科学数据共享中心提供的汶川8.0级地震目录资料,对2008年5月12日至2010年3月1日共1 613次3.0级及以上余震的地震序列进行了时空分布分析.结果表明:汶川8.0级地震的余震大致可分为7个阶段,主震后18天应列为大地震强余震发生的警戒时间;地震序列的b值为0.751,印证了在类型相同的情况下主震震级越大b值越高的观点;地震序列的p值为1.117,与全球地震衰减速率相当;汶川地震的余震分布主要沿龙门山断裂走向北东向扩展,且具有明显分区性,自南向北分为南、中、北3区段,南区为地震起始破裂段,地震后期余震则主要分布在北区;震源深度分布在10～40 km,集中在10～20 km,表明龙门山断裂主要发生在中上地壳,且震源深度由南向北呈现逐渐变浅的趋势;震源深度扩展,南区呈明显脉冲状,中区主要是依次由15、30、25 km深度向深、浅层同时扩展,北区余震深度分布呈“乙”字型,最后稳定在15 km左右. 相似文献
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基于宽频带倾斜仪数据,利用震源扫描算法(SSA)对地震进行定位,结果表明:在3个台站的情况下,对于网外地震,速度取均匀球壳模型,其定位精度随地震距台网距离增加而降低,在地震距最近台站为837 km时,经向误差为-1.11°,纬向误差为2.73°。同时,发现2008年12月—2009年4月期间黄梅台、宁陕台的宽频带倾斜仪时间系统可能存在故障。 相似文献
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孙鸿烈 《地球信息科学学报》2010,(5):741-741
2010年4月14日青海玉树地震,给地震灾区人民的生命财产造成巨大的伤害和损失,全国人民感同身受。作为从事地理科学、资源科学和生态环境等研究的国家科研机构,有责任为国分忧,为灾区政府和人民服务,为灾区恢复重建贡献我们的知识和经验。因此,中国科学院地理科学与资源研究所一批长期在三江源地区开展研究工作的科研人员提出, 相似文献
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退耕还林（草）等生态工程对区域用地结构及生态系统服务功能产生了重要影响。本研究基于RUSLE模型,并辅以遥感监测与GIS空间分析方法,对北方农牧交错带西段2000-2015年退耕状况及其引起的土壤保持功能变化分3个时段（2000-2005年、2005-2010年及2010-2015年）进行了探究。结果表明：北方农牧交错带西段地区2000-2015年耕地面积净减少1663.83 km2,以转为林地、草地、建设用地为主,其中耕地转林、草地净减少面积为1113.64 km2,草地和未利用地是新增耕地的主要来源;15年间土壤保持功能提升显著,退耕还林（草）工程的实施使土壤保持量增加了56.50×104 t,2005-2010年由退耕所带来的土壤保持增加量在3段时期中最高;不同坡度等级的生态退耕引起的土壤保持增加量差别较大,总体随着坡度升高呈下降趋势,但在25°以上的陡坡耕地由退耕还林（草）带来的土壤保持效益又有所升高。研究对于评估北方农牧交错带西段地区实施退耕还林（草）等工程的生态效益具有重要意义,并能为区域生态保护与修复工程的建设规划提供科学依据。 相似文献
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Changes in ecosystem service of soil conservation between 2000 and 2010 and its driving factors in southwestern China 总被引：2，自引：0，他引：2
Human activities significantly alter ecosystems and their services; however, quantifying the impact of human activities on ecosystems has been a great challenge in ecosystem management. We used the Universal Soil Loss Equation and county-level socioeconomic data to assess the changes in the ecosystem service of soil conservation between 2000 and 2010, and to analyze its spatial characteristics and driving factors in the southwestern China. The results showed that cropland in the southwestern China decreased by 3.74%, while urban land, forest, and grassland areas increased by 46.78%, 0.86%, and 1.12%, respectively. The soil conservation increased by 1.88 × 10~(11) kg, with deterioration only in some local areas. The improved and the degraded areas accounted for 6.41% and 2.44% of the total land area, respectively. Implementation of the Sloping Land Conversion Program and urbanization explained 57.80% and 23.90% of the variation in the soil conservation change, respectively, and were found to be the main factors enhancing soil conservation. The 2008 Wenchuan earthquake was one of the factors that led to the degradation of soil conservation. Furthermore, industrial adjustment, by increasing shares of Industry and Service and reducing those of Agriculture, has also promoted soil conservation. Our results quantitatively showed and emphasized the contributions to soil conservation improvement made by implementing ecological restoration programs and promoting urbanization. Consequently, these results provide basic information to improve our understanding of the effects of ecological restoration programs, and help guide future sustainable urban development and regional industrial restructuring. 相似文献
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《山地科学学报》2021,(4)
The Wenchuan earthquake that occurred on 12 May 2008 induced numerous landslides. Loose landslide materials were deposited on hillslopes, and deep channels were easily remobilized and transformed into debris flows by extreme rainstorms. Twelve years after the Wenchuan earthquake, debris flows were still active in the Qipangou Ravine in the quake-hit area. In this paper, we continuously tracked the spatiotemporal evolution of the landslides and vegetation restoration and evaluated the evolution of debris flow activity in the Qipan catchment with the aid of a GIS platform and field investigations from 2008 to 2019. We observed that the area with active landslides increased sharply immediately following the earthquake, and then decreased with time; however, the total area of landslides continued to increase from 6.93 km2 in 2008 to 10.55 km2 in 2019. The active landslides shifted towards lower angles and higher elevations after 2013. Since 2009, the vegetation coverage has been gradually increasing and approaching the coverage present before the earthquake as of 2019. The landslide activity was high and the vegetation recovery rates were rapidly rising during the first five years after the earthquake; the recovery rates then slowed over time. Therefore, we divided the evolution that occurred during the post landslide period into an active period(2008-2013), a self-adjustment period(2013-2026) and a stable period(after 2026). We then proposed a quantitative model to determine the trends of landslide activity rates and NDVI values in the catchment, which indicated that the landslide activities and postseismic vegetation restoration rates in this catchment will return to preseismic levels within approximately two decades. We also analysed the runout volumes of the debris flows after the earthquakes(Diexi and Wenchuan) and the standard deviation of the vegetation coverage and predicted that the debris flow activities will last for an additional 50 years or more. 相似文献
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基于随机森林算法的草原地上生物量遥感估算方法研究 总被引：1，自引：0，他引：1
草原是我国面积最大的陆地生态系统,生物量是反映生态系统质量和功能的关键指标,准确地掌握草原生物量对草原资源合理利用、生态修复、畜牧业高质量发展都具有重要的意义和作用。本研究以内蒙古锡林郭勒盟为研究区,利用高分一号遥感卫星影像,结合216个野外样本数据,采用随机森林算法（Random Forest,RF）对草原地上生物量（Aboveground Biomass,AGB）遥感估算进行了适用性分析与应用。在运用随机森林算法的过程中,进行了K-折交叉验证、多元共线性诊断、偏效应等一系列分析,完成了随机森林模型的构建,同时,将建模结果与其它模型进行了对比,最终实现了锡林郭勒盟草原AGB的反演估算。结果表明：① 随机森林算法能够较好地规避生物量建模中自变量多元共线性的问题;② 随机森林模型在草原AGB估算中较其它模型具有更好的适用性,模型精度达85%,RMSE为202.13 kg/hm2;③ 应用构建的随机森林算法估算了研究区2017年草原AGB,从结果来看,其空间分布上呈现为自东向西逐渐递减的趋势;从草地类型上看,山地草甸类AGB单产最高,温性草原类总产量最高。研究结果将对草原生态系统监测评估和草原宏观管理具有一定的参考价值。 相似文献
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近20年黄土高原土地利用/覆被变化特征分析 总被引：5，自引：0，他引：5
本文根据黄土高原地区20世纪80年代末、2000年、2008年3期土地利用/覆被空间数据集,计算2个时段（20世纪80年代末-2000年,2000-2008年）土地利用/覆被转类方向及其幅度、土地利用/覆被转类指数、土地利用/覆被状况指数及其变化率,分析黄土高原地区自20世纪80年代末以来土地利用/覆被时空变化特征以及宏观生态状况的变化趋势。结果显示：黄土高原地区近20年来平均土地利用/覆被状况指数为24.07,其中土石山区生态系统综合功能最好,其次为河谷平原区,最差的为农灌区。20世纪80年代末-2000年,黄土高原地区主要土地利用/覆被转类是森林和草地转为耕地,生态级别由高级向低级转移,2000-2008年主要土地利用/覆被转类是耕地转为林地和草地,低覆盖草地转为中高覆盖草地,生态级别由低级向高级转移。近20年来黄土高原地区地覆被状况指数变化以及土地利用/覆被转类指数表明,该区域的宏观生态状况总体上经历了转差（20世纪80年代末-2000年土地利用/覆被转类指数为-1.08）,后转好（2000-2008年土地利用/覆被转类指数为2.66）2个过程。这一变化过程前期受区域气候变化以及人口增长共同驱动,后期则叠加了生态工程的影响。 相似文献
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全球气候变化背景下,“一带一路”沿线国家农田生态系统脆弱性直接影响着所在国家或地区的粮食安全问题。本文基于农田生态系统总初级生产力（GPP）,使用定量的脆弱性评价方法,系统分析了“一带一路”沿线国家农田生态系统脆弱性的空间分布特征及其对气候变化的响应。结果表明：① “一带一路”沿线国家农田生态系统脆弱性普遍处于较高的程度,77.1%的农田生态系统表现为中度和重度脆弱,且农田生态系统脆弱性呈现出明显的空间分异格局,中亚、西亚和蒙古脆弱性较高,中国、东南亚和南亚的脆弱性处于中等水平,俄罗斯、独联体和中东欧脆弱性较低;② 1980年以来“一带一路”沿线农田生态系统暖干化趋势明显,暖干化区域面积占64.06%,暖干化是“一带一路”沿线国家农田生态系统气候变化的主要特征;③ 农田生态系统脆弱性由低到高的气候变化区依次为暖湿区、冷湿区、暖干区、冷干区。暖湿区农田生态系统脆弱性最低,而冷干区农田生态系统脆弱性最高。气温和降水的变化及其耦合关系控制着农田生态系统脆弱性程度,其中降水变化趋势是影响农田生态系统脆弱性的重要因子。本研究为“一带一路”沿线国家应对和解决粮食安全问题,促进农业可持续发展,为加强各国之间的农业国际合作提供科学依据和有益参考。 相似文献
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Massive geological landslides and unstable landslide areas were triggered by the 2008 Wenchuan earthquake. These landslides caused deaths, damaged infrastructure and threatened endanger species. This study analyzed the impact of landslides on giant pandas and their habitats from the following aspects: threatening pandas‘ lives, damaging pandas‘ habitat, influencing giant panda behavior, increasing habitat fragmentation; the final aspect, and blocking gene flow by cutting off corridors. A habitat suitability map was created by integrating the landslide factors with other traditional factors based on a logistics regression method. According to the landslide inventory map, there are 1313 landslides, 818 rock debris flows, 117 rock avalanches and 43 mud flows occurred in the study area. A correlation analysis indicated that landslides caused the pandas to migrate, and the core landslides within 1 km2 had greater influence on panda migration. These core landslides primarily occurred in mid-altitude regionscharacterized by high slopes, old geological ages, large areas and large rock mass volumes. The habitat suitability assessment results for the Wolong Natural Reserve had better prediction performance(80.9%) and demonstrated that 14.5%, 15.9%, 20.5%, 47.6% and 1.5% of the study area can be classified as very high, high, moderate, low and very low giant panda suitability areas, respectively. This study can be used to inform panda and panda habitat research, management and protection during post-quake reconstruction and recovery periods in China. 相似文献
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??????M8.0????????????????????С???????????????????о???????????λ????????????????????ν???ие???????????????????1??M8.0??????????????????????????????????????С????????????????????????????????????????????????42°????????????????????????????20 km??2?????????????????????????????????????10 km?????????????????С??????????????????????????????????????????????????????λ?????????7 km??3??2??14??
ML3.7?????????????????93°?????????????????????С??????????????????????????????????2???????￡????????????????????????????????????????????????????????????????4??2??28??ML3.8?????????λ?????????????????????????????????????????????????????????￡???????????? 相似文献
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基于改进Markov-CA模型的黄土高原土地利用多情景模拟 总被引：2，自引：0，他引：2
土地利用/覆被的时空变化研究能为区域生态环境恢复和生态系统集成管理提供科学支持。集成Logistic回归模型、改进的Markov与FLUS模型模拟黄土高原2020—2050年3种典型情景土地利用变化。发现各情景土地利用面积变化及空间置换转移主要集中在农用地、草地和城镇用地;历史趋势延续情景下农用地减少15 205 km2,草地、城镇用地分别增加2742 km2和16 007 km2;生态保育管护情景中草地增加7076 km2,林草用地增长存在权衡关系（r主要林地-草地=-0.66）,在典型区域的生态恢复管理中应加以重视;城镇发展建设情景中农用地减少20 256 km2,城镇用地增加22 032 km2,变化均达到极值,其中,南部城镇扩张与农用地减少存在强权衡关系（r农用地-城镇用地=-1）。改进的Markov-FLUS模型适用于黄土高原地区的土地利用模拟,情景分析可有效揭示区域生态保护与城镇扩张的阈值变化,为区域土地利用政策权衡管理和水土保育提供科学依据。 相似文献
20.
On 12 May 2008, the magnitude 8.0 Wenchuan Earthquake occurred along the Longmen Shan nappe, Sichuan, China. This devastating earthquake led to a heavy death toll of greater than 80,000. The seismic origin of this earthquake is currently hotly debated. We suppose that it is a special type of intraplate earthquake called an active-nappe-type earthquake. Using a holistic methodology, incorporating rockmass structure cybernetics and Byerlee’s law, we present a comprehensive study on the geological origin of macroseisms in the Longmen Shan area and the seismic origin of the 2008 Wenchuan earthquake. Previous studies of neotectonic activity indicate that the Longmen Shan nappe moves at a rate of 1~3 mm/yr, due to horizontal compressive stress from the Tibetan Plateau. The difference between movement rates in the Bayankala block, Longmen Shan nappe and Sichuan Basin cause slow shear stress and strain accumulation in the Longmen Shan nappe. It is exhibited a relatively simple linear relations for the shear strength and the buried depth of the structural planes, and the detachment layer of the nappe has a higher shearing-sliding strength compared to the overlying fault planes and the underlying ductile shear belts, thus making it more prone to stick-slip deformation. Therefore, the detachment layer was the main section responsible for the Wenchuan earthquake. The initial rupture burst in the detachment layer under the Yingxiu-Beichuan fault, the rupture area nearly 1.4454 × 104 km2,encompassed the cross point of the Yingxiu and the Anxian-Guanxian faults with the detachment layer, then caused the Yingxiu-Beichuan and Anxian-Guanxian faults took an active part in this earthquake, so this earthquake might consist of three chain-like earthquake stages, totally increasing the duration of this earthquake an unusually large amount, to 120 s. The focal depth spanned range of 10-20km,consistent with the observed result of this focal depth by several agencies. 相似文献