Seismic Risk Assessment and Maximum Magnitudes of Potential Earthquakes on Active Faults near Lanzhou City     

Liang Mingjian    Yuan Daoyang    Liu Baiehi    Lei Zhongsheng   《中国地震研究》2009,23(3):319-327

The Zhuanglang river and Baiyin Baiyangshu river faults are late Quaternary faults near Lanzhou city,which pose a threat to the safety of the city. However,the cause of medium-strong earthquakes along the fault is rather complicated and even uncertain. It is important for us how to assess the magnitudes of maximum potential earthquakes and the seismic risk of the faults. The authors make reference to the method that Wen Xueze,et al.(2007) developed to assess the magnitudes of maximum potential earthquakes in sub-areas of moderately and weakly active faults in the eastern Chinese Mainland,and brought forward an empirical relationship between the maximum magnitudes M_max and the a_t/b values of the sub-areas' frequency-magnitude relationships in the Lanzhou area. By using this empirical relationship,the authors have estimated the upper-limits M_u of the Zhuanglang river and Baiyin Baiyangshu river active faults near Lanzhou city as M_S6.9 and 6.3,respectively. In addition,they have assessed the average interval recurrence time and the probabilities of destructive earthquakes on the faults.  相似文献   

1219年宁夏固原地震考证与发震构造探讨          下载免费PDF全文

袁道阳  雷中生  张俊玲  刘百篪  梁明剑 《地震学报》2008,30(6):648-657

根据对历史地震资料的考证和实地调查,论证了公元1219年宁夏固原地震应为一次地震,而不是二次或三次地震。现行地震目录所给的地震参数宜做如下修正:发震时间为8月7日11时左右;地震重破坏区（Ⅷ度区）位于固原、平凉和隆德一带,极震区介于三者之间的固原附近;震中烈度ge;Ⅸ度,震级可达7级左右。本次地震重破坏区长轴方向为北北西向,大致与该区的六盘山逆掩推覆构造带的走向相吻合,其新构造活动导致了1219年固原地震的发生。   相似文献   

Molecular Fingerprints of Soil Organic Matter in a Typical Freshwater Wetland in Northeast China     

LI Zhe  ZHANG Zhongsheng  XUE Zhenshan  SONG Xiaolin  ZHANG Hongri  WU Haitao  JIANG Ming  LYU Xianguo 《中国地理科学(英文版)》2019,(4):700-711

Natural wetlands are known to store huge amounts of organic carbon in their soils. Despite the importance of this storage,uncertainties remain about the molecular characteristics of soil organic matter(SOM), a key factor governing the stability of soil organic carbon(SOC). In this study, the molecular fingerprints of SOM in a typical freshwater wetland in Northeast China were investigated using pyrolysis gas-chromatography/mass-spectrometry technology(Py-GC/MS). Results indicated that the SOC, total nitrogen(TN),and total sulfur contents of the cores varied between 16.88% and 45.83%, 0.93% and 2.82%, and 1.09% and 3.79%, respectively. The bulk δ^13C and δ^15N varied over a range of 9.85‰, between –26.85‰ and –17.00‰, and between –0.126‰ and 1.002‰, respectively. A total of 134 different pyrolytic products were identified, and they were grouped into alkyl(including n-alkanes(C:0) and n-alkenes(C:1),aliphatics(Al), aromatics(Ar), lignin(Lg), nitrogen-containing compounds(Nc), polycyclic aromatic hydrocarbons(PAHs), phenols(Phs), polysaccharides(Ps), and sulfur-containing compounds(Sc). On average, Phs moieties accounted for roughly 24.11% peak areas of the total pyrolysis products, followed by Lg(19.27%), alkyl(18.96%), other aliphatics(12.39%), Nc compounds(8.08%), Ps(6.49%), aromatics(6.32%), Sc(3.26%), and PAHs(1.12%). Soil organic matter from wetlands had more Phs and Lg and less Nc moieties in pyrolytic products than soil organic matters from forests, lake sediments, pastures, and farmland.δ^13 C distribution patterns implied more C3 plant-derived soil organic matter, but the vegetation was in succession to C4 plant from C3 plant. Significant negative correlations between Lg or Ps proportions and C3 plant proportions were observed. Multiple linear analyses implied that the Ar and Al components had negative effects on SOC. Alkyl and Ar could facilitate ratios between SOC and total nitrogen(C/N), while Al plays the opposite role. Al was positively related to the ratio of dissolved organic carbon(DOC) to SOC. In summary, SOM of wetlands might characterize by more Phs and lignin and less Nc moieties in pyrolytic products. The use of Pyrolysis gas-chromatography/mass-spectrometry(Py-GC/MS) technology provided detailed information on the molecular characteristics of SOM from a typical freshwater wetland.  相似文献   

Effect of Wetland Reclamation on Soil Organic Carbon Stability in Peat Mire Soil Around Xingkai Lake in Northeast China     

Lili Huo  Yuanchun Zou  Xianguo Lyu  Zhongsheng Zhang  Xuehong Wang  Yi An 《中国地理科学(英文版)》2018,28(2):325-336

Content and density of soil organic carbon(SOC) and labile and stable SOC fractions in peat mire soil in wetland, soybean field and rice paddy field reclaimed from the wetland around Xingkai Lake in Northeast China were studied. Studies were designed to investigate the impact of reclamation of wetland for soybean and rice farming on stability of SOC. After reclamation, SOC content and density in the top 0–30 cm soil layer decreased, and SOC content and density in soybean field were higher than that in paddy field. Content and density of labile SOC fractions also decreased, and density of labile SOC fractions and their ratios with SOC in soybean field were lower than that observed in paddy field. In the 0–30 cm soil layer, densities of labile SOC fractions, namely, dissolved organic carbon(DOC), microbial biomass carbon(MBC), readily oxidized carbon(ROC) and readily mineralized carbon(RMC), in both soybean field and paddy field were all found to be lower than those in wetland by 34.00% and 13.83%, 51.74% and 35.13%, 62.24% and 59.00%, and 64.24% and 17.86%, respectively. After reclamation, SOC density of micro-aggregates( 0.25 mm) as a stable SOC fraction and its ratio with SOC in 0–5, 5–10, 10–20 and 20–30 cm soil layers increased. SOC density of micro-aggregates in the 0–30 cm soil layer in soybean field was 50.83% higher than that in paddy field. Due to reclamation, SOC density and labile SOC fraction density decreased, but after reclamation, most SOC was stored in a more complex and stable form. Soybean farming is more friendly for sustainable SOC residence in the soils than rice farming.  相似文献   

Effects of Biochar Application on Soil Organic Carbon in Degraded Saline-sodic Wetlands of Songnen Plain,Northeast China     

CHE Qianjin  LI Min  ZHANG Zhongsheng 《中国地理科学(英文版)》2021,(5):877-887

Biochar amendment is considered as an efficient practice for improving carbon storage in soils. However, to what extent that biochar application promotes organic carbon in saline-sodic soils remains poorly understood. By comparing soil organic carbon(SOC)contents change before and after biochar addition, we deciphered the driving factors or processes that control SOC change in response to biochar application. A limited increase in SOC was observed, about by 1.16%-12.80%, even when biochar was applied at the rate of 10% of bulk soil weight. Biochar application enhanced soil dissolved organic carbon(DOC) significantly by up to 67%. It was estimated that about 50% SOC was allocated to small macroaggregates(250-2000 μm, CPOC), and SOC in silt and clay-sized particles( 53 μm) decreased obviously after biochar addition. Microbial biomass increased with biochar amendment, of which actinomycetes(ACT), fungus(FUN), protozoon(PRO), and bacteria with straight-chain saturated fatty acids(OB) increased remarkably. Multiple linear regression models implied that DOC was governed by ACT and soil N∶P ratio, while SOC mostly depended on CPOC. The principal component analysis and the partial least square path model(PLS-PM) indicated that biochar addition aggravated nitrogen limitation in saline-sodic soils, and effects of microorganisms on regulating SOC greatly depended on nitrogen bioavailability. Biochar application had vastly changed interactions between environmental factors and SOC in saline-sodic soils. Effects of nutrients on SOC shifted to great inhibition from strong stimulation after biochar addition, meanwhile, aggregation was the only factor presenting positive effects on SOC. How to eliminate nutrient limitation and better soil aggregation process should be considered in priority when biochar was used to improve SOC in saline-sodic soils.  相似文献   

Hydrogeological analysis and salvage of a deep coalmine after a groundwater inrush   总被引：3，自引：0，他引：3  

Wanghua Sui  Jinyuan Liu  Siguang Yang  Zhongsheng Chen  Yisheng Hu 《Environmental Earth Sciences》2011,62(4):735-749

This paper presents a case history of the permanent salvage of the Sanhejian Coalmine in China after a sudden groundwater inrush, which includes emergency responses, hydrogeological analyses, and design and performance of bulkheads. The inrush accident occurred in October 2002 in the mined-out area with a high water pressure of 7.6 MPa and a high water temperature of 51°C. The emergency response quickly followed up to provide the time required to perform a detailed hydrogeological analysis to identify the source and pathway of groundwater. The Sanhejian Coalmine is geologically located in the Tengxian anticline hydrogeological setting. The Sunshidian fault, the northern boundary of the mine, was assumed impermeable in the original hydrogeological report. After the accident and hydrogeological analysis, this assessment was revised and the fault was considered to be permeable. The Sunshidian fault connects the strata in the mine and the excellent water-productive Middle Ordovician Majiagou Formation in the core of the Tengxian anticline. It was concluded that the water inrush was from the underlying Ordovician karst aquifer and the pathway was a hidden tectonic structure in the strata overlying the aquifer. This assessment served as the guideline for salvaging the mine in this project. After a detailed technical and economic analysis, a concrete bulkhead design was selected from several alternatives including dewatering and surface grouting. The performance of the bulkheads has been sufficient for the last 6 years since their construction. This case history shows that the hydrogeological analysis plays an essential role in successfully salvaging the coalmine from the water inrush by identifying the source and pathway of groundwater.  相似文献   

Modelling the petroleum generation and migration of the third member of the Shahejie Formation (Es3) in the Banqiao Depression of Bohai Bay Basin,Eastern China     

Xiaowen Guo  Sheng He  Keyu Liu  Zhongsheng Shi  Sani Bachir 《Journal of Asian Earth Sciences》2011,40(1):287-302

The mudstones in the third member of the Shahejie Formation (Es3) are the primary source rocks in the Banqiao Depression of Bohai Bay Basin. They are rich in organic matter with Total Organic Carbon (TOC) content up to 3.5%. The sandstones in the Es3 member are the deepest proven hydrocarbon reservoir rocks with measured porosity and permeability values ranging from 3.6% to 32.4% and from 0.01 md to 3283.7 md, respectively. One, two and three-dimensional basin modelling studies were performed to analyse the petroleum generation and migration history of the Es3 member in the Banqiao Depression based on the reconstruction of the burial, thermal and maturity history in order to evaluate the remaining potential of this petroleum province. The modelling results are calibrated with measured vitrinite reflectance (R_o), borehole temperatures and some drilling results of 63 wells in the study area. Calibration of the model with thermal maturity and borehole temperature data indicates that the present-day heat flow in the Banqiao Depression varies from 59.8 mW/m² to 61.7 mW/m² and the paleo-heat flow increased from 65 Ma to 50.4 Ma, reached a peak heat-flow values of approximately 75 mW/m² at 50.4 Ma and then decreased exponentially from 50.4 Ma to present-day. The source rocks of the Es3 member are presently in a stage of oil and condensate generation with maturity from 0.5% to 1.8% R_o and had maturity from 0.5% to 1.25% R_o at the end of the Dongying Formation (Ed) deposition (26 Ma). Oil generation (0.5% R_o) in the Es3 member began from about 37 Ma to 34 Ma and the peak hydrocarbon generation (1.0% R_o) occurred approximately from 30 Ma to 15 Ma. The modelled hydrocarbon expulsion evolution suggested that the timing of hydrocarbon expulsion from the Es3 member source rocks began from 31 Ma to 10 Ma with the peak hydrocarbon expulsion shortly after 26 Ma. Secondary petroleum migration pathways in the Es3 member of the Banqiao Depression are modelled based on the structure surfaces at 26 Ma and present-day, respectively. The migration history modelling results have accurately predicted the petroleum occurrences within the Es3 member of the Banqiao Depression based on the calibration with drilling results of 10 oil-producing wells, one well with oil shows and 52 dry holes. Six favorable zones of oil accumulations in the Es3 member of the Banqiao Depression are identified especially oil accumulation zones I and II due to their proximity to the generative kitchens, short oil migration distances and the presence of a powerful drive force.  相似文献   

映秀-北川断裂带北川段唐家湾滑坡活动历史与形成机制          下载免费PDF全文

田尤  黄海  谢忠胜  佘涛  李金洋 《沉积与特提斯地质》2023,43(3):629-639

以映秀-北川断裂带北川段唐家湾滑坡为研究对象,基于地形资料、多期遥感与航拍影像,结合¹⁴C测年的方法,细分了唐家湾滑坡的活动历史,分析了2016年唐家湾滑坡再次复活的主要控制因素。研究结果表明：（1）唐家湾斜坡历史上至少发生过四期滑动,其中第一期次滑坡发生在全新世以前;第二期次滑坡发生于全新世初期;第三期次滑坡发生在2008年汶川地震时期,系龙门山断裂带活动过程中产生的同震滑坡;第四期次滑坡分别发生在2016年和2018年,属于断裂带滑坡堆积体的再次局部复活;（2）2016年唐家湾滑坡的形成与断裂活动、河流侧蚀和水等因素有关,其中,上覆滑坡堆积体、下伏高陡基岩形成的二元斜坡结构,是唐家湾滑坡发生的决定性条件;断裂活动及其导致的浅地表最大主应力偏转是唐家湾滑坡变形的重要内因;（3）以唐家湾滑坡为例,初步讨论了基于地形条件控制的断裂带滑坡堆积体复活的地质模型,其形成演化表现为断裂带活动和河流侵蚀形成滑坡（或陡峭地形）→先期滑坡后壁（或陡峭地形）接受上部老滑坡堆积→二元斜坡结构控制下的老滑坡复活变形。该滑坡为研究地形控制断裂带滑坡复活提供了独特的案例,研究成果对于理解和评估该类滑坡,开展综合防治等方面具有重要的借鉴价值。  相似文献   

中美两国的地裂缝灾害   总被引：6，自引：0，他引：6       下载免费PDF全文

耿大玉  李忠生 《地震学报》2000,22(4):433-441

无震地裂现象常与地面沉降相伴生,在中国的7个省、美国的6个州致灾严重．中国现代地裂灾害观察研究滞后于美国约半个世纪．两国地裂的形成、演化、致灾及对策诸方面的对比研究表明,地裂灾害属自然与人类活动因素相叠加而引起的环境地质灾害．构造因素决定了地裂出现的位置,而人类活动因素,即过量开采地下水、石油等,决定了地裂致灾的强度．因而,相应的减灾措施既有科学技术方面的,也有社会管理方面的．本文给出的两国减灾实例可供参考．   相似文献   

Paleoseimic Record at the Salt Lake Site on the Haiyuan Fault, China:Implications for Concepts of Surface Rupturing Event and Earthquake Recurrence Interval     

LIU Jing  SHAO Yanxiu  XIE Keji  Yann Klinger  LEI Zhongsheng  YUAN Daoyang 《《地质学报》英文版》2013,87(Z1):366-366

  相似文献