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THE RESEARCH OF THE SEISMOGENIC STRUCTURE OF THE LUSHAN EARTHQUAKE BASED ON THE SYNTHESIS OF THE DEEP SEISMIC DATA AND THE SURFACE TECTONIC DEFORMATION
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WANG Lin ZHOU Qing-yun WANG Jun LI Wen-qiao ZHOU Lian-qing CHEN Han-lin SU Peng LIANG Peng 《地震地质》2016,38(2):458-476
The seismogenic structure of the Lushan earthquake has remained in suspensed until now. Several faults or tectonics, including basal slipping zone, unknown blind thrust fault and piedmont buried fault, etc, are all considered as the possible seismogenic structure. This paper tries to make some new insights into this unsolved problem. Firstly, based on the data collected from the dynamic seismic stations located on the southern segment of the Longmenshan fault deployed by the Institute of Earthquake Science from 2008 to 2009 and the result of the aftershock relocation and the location of the known faults on the surface, we analyze and interpret the deep structures. Secondly, based on the terrace deformation across the main earthquake zone obtained from the dirrerential GPS meaturement of topography along the Qingyijiang River, combining with the geological interpretation of the high resolution remote sensing image and the regional geological data, we analyze the surface tectonic deformation. Furthermore, we combined the data of the deep structure and the surface deformation above to construct tectonic deformation model and research the seismogenic structure of the Lushan earthquake. Preliminarily, we think that the deformation model of the Lushan earthquake is different from that of the northern thrust segment ruptured in the Wenchuan earthquake due to the dip angle of the fault plane. On the southern segment, the main deformation is the compression of the footwall due to the nearly vertical fault plane of the frontal fault, and the new active thrust faults formed in the footwall. While on the northern segment, the main deformation is the thrusting of the hanging wall due to the less steep fault plane of the central fault. An active anticline formed on the hanging wall of the new active thrust fault, and the terrace surface on this anticline have deformed evidently since the Quaterary, and the latest activity of this anticline caused the Lushan earthquake, so the newly formed active thrust fault is probably the seismogenic structure of the Lushan earthquake. Huge displacement or tectonic deformation has been accumulated on the fault segment curved towards southeast from the Daxi country to the Taiping town during a long time, and the release of the strain and the tectonic movement all concentrate on this fault segment. The Lushan earthquake is just one event during the whole process of tectonic evolution, and the newly formed active thrust faults in the footwall may still cause similar earthquake in the future. 相似文献
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基于2012—2019年兰州地区146个区域自动气象站小时降水数据,从不同时间尺度分析兰州地区近8 a降水精细化特征。结论如下:(1)2012—2019年,兰州地区年均降水量总体呈"北少南多、外多内少"的空间分布特征;年降水量具有明显的年际变化,2018年降水异常偏多46%,而2015、2017年降水异常偏少,尤其2015年偏少30%。(2)兰州地区降水主要集中在7—8月,受环流形势影响,7—8月南部降水明显多于北部,其余月份南北降水差异不明显。(3)兰州地区降水量和降水范围分别表现为"朝少夕多"、"夜大日小"的日变化特征;受海拔高度影响,城区降水量总体比山区小,且因热岛效应,城区降水主要集中在午后至傍晚前后,多为对流性降水,而山区降水日分布较为均匀,整体日波动较小。(4)安宁区短时强降水发生频次最高,但短时强降水频发的站点出现在皋兰县六合站和永登县徐家磨村站,永登县是兰州地区短时强降水预报需重点关注的地区。 相似文献
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基于2012—2019年兰州地区146个区域自动气象站小时降水数据,从不同时间尺度分析兰州地区近8 a降水精细化特征。结论如下:(1)2012—2019年,兰州地区年均降水量总体呈"北少南多、外多内少"的空间分布特征;年降水量具有明显的年际变化,2018年降水异常偏多46%,而2015、2017年降水异常偏少,尤其2015年偏少30%。(2)兰州地区降水主要集中在7—8月,受环流形势影响,7—8月南部降水明显多于北部,其余月份南北降水差异不明显。(3)兰州地区降水量和降水范围分别表现为"朝少夕多"、"夜大日小"的日变化特征;受海拔高度影响,城区降水量总体比山区小,且因热岛效应,城区降水主要集中在午后至傍晚前后,多为对流性降水,而山区降水日分布较为均匀,整体日波动较小。(4)安宁区短时强降水发生频次最高,但短时强降水频发的站点出现在皋兰县六合站和永登县徐家磨村站,永登县是兰州地区短时强降水预报需重点关注的地区。 相似文献
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Chao LIU Shu YANG Di DI Yuanjian YANG Chen ZHOU Xiuqing HU Byung-Ju SOHN 《大气科学进展》2022,39(12):1994-2007
Cloud Masking is one of the most essential products for satellite remote sensing and downstream applications. This study develops machine learning-based (ML-based) cloud detection algorithms using spectral observations for the Advanced Himawari Imager (AHI) onboard the Himawari-8 geostationary satellite. Collocated active observations from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) are used to provide reference labels for model development and validation. We introduce both daytime and nighttime algorithms that differ according to whether solar band observations are included, and the artificial neural network (ANN) and random forest (RF) techniques are adopted for comparison. To eliminate the influences of surface conditions on cloud detection, we introduce three models with different treatments of the surface. Instead of developing independent ML-based algorithms, we add surface variables in a binary way that enhances the ML-based algorithm accuracy by ~5%. Validated against CALIOP observations, we find that our daytime RF-based algorithm outperforms the AHI operational algorithm by improving the accuracy of cloudy pixel detection by ~5%, while at the same time, reducing misjudgment by ~3%. The nighttime model with only infrared observations is also slightly better than the AHI operational product but may tend to overestimate cloudy pixels. Overall, our ML-based algorithms can serve as a reliable method to provide cloud mask results for both daytime and nighttime AHI observations. We furthermore suggest treating the surface with a set of independent variables for future ML-based algorithm development. 相似文献
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以老挝甘蒙省钾镁盐矿床ZK318钻孔的含矿段(下盐层)为研究对象,对其开展了微量硼矿物的鉴定研究工作,以完善矿床的矿物组合类型。全岩样品的XRD初步结果给出,在顶部钾盐岩层中含有少量方硼石。为了进一步全面鉴定硼矿物的种类,对全岩样品溶解后得到的不溶物多晶集合体进行XRD分析,结果表明,不溶物中的硼矿物主要为方硼石(55%),其次为三斜晶系3A型氯硼钙石(15%)。3A型氯硼钙石在全岩样品中的含量不足1%,属微量矿物,因低于XRD的检出限,故在全岩样品的XRD图谱中无该矿物的衍射峰出现。此外,对三斜晶系3A型氯硼钙石的中文准确命名进行了讨论,指出中文定名应与国际惯例一致,即废除副水氯硼钙石(parahilgardite)一词,定名为3A型氯硼钙石(hilgardite-3A)以体现结构的微细差别,同时达到中文命名规范统一的目的。因此,该矿床中的硼矿物为少量方硼石和微量3A型氯硼钙石。 相似文献
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2010年“8.8”舟曲特大山洪泥石流灾害形成的气候特征及地质地理环境分析 总被引:2,自引:2,他引:0
利用舟曲气象和地质资料,分析了2010年8月8日发生的"8.8"舟曲特大山洪泥石流灾害形成的气候特征和地质地理环境.这次泥石流是在舟曲特殊的地质地貌和地理环境下,由于前期干旱,突遇强降水而发生的一次特大地质灾害.崩塌、滑坡、地震和人为因素,特别是"5.12"汶川地震,较大程度上破坏了舟曲地质,为泥石流提供了丰富的物质来源;前期干旱在一定程度上加剧了这次灾害;超历史极值的强降水是触发泥石流的直接因素.通过对舟曲气候研究表明,7、8月降雨频繁,而且过程雨量大,尤其8月上旬大雨发生频率最高,应密切关注可能引发的地质灾害.加强对地质地貌的保护,研究历史气候及月季气候特征对泥石流发生的影响,确定在不同地形和地质地貌背景下的泥石流降水量阈值,对泥石流灾害发生的预报有着十分重要的意义. 相似文献