祁连山构造带地震迁移活动特征分析

祁连山构造带地震迁移活动研究表明,存在不同震级层次的地震迁移现象:①大震顺构造带迁移由东而西震级衰减;②中强地震沿构造带东、中、西段交替发生;③横构造带地震跳迁会影响顺构造带地震的有序迁移;④祁连山中东段—东段存在发生破坏性地震的背景。     

Merging of Airborne Gravity and Gravity Derived from Satellite Altimetry: Test Cases Along the Coast of Greenland

The National Survey and Cadastre - Denmark (KMS) has for several years produced gravity anomaly maps over the oceans derived from satellite altimetry. During the last four years, KMS has also conducted airborne gravity surveys along the coast of Greenland dedicated to complement the existing onshore gravity coverage and fill in new data in the very-near coastal area, where altimetry data may contain gross errors. The airborne surveys extend from the coastline to approximately 100 km offshore, along 6000 km of coastline. An adequate merging of these different data sources is important for the use of gravity data especially, when computing geoid models in coastal regions.The presence of reliable marine gravity data for independent control offers an opportunity to study procedures for the merging of airborne and satellite data around Greenland. Two different merging techniques, both based on collocation, are investigated in this paper. Collocation offers a way of combining the individual airborne gravity observation with either the residual geoid observations derived from satellite altimetry or with gravity derived from these data using the inverse Stokes method implemented by Fast Fourier Transform (FFT).     

Thermal Anomalies and Earthquakes： Evidence from Wenchuan, China

Earthquake prediction is a difficult problem in Earth sciences.Unsuccessful predictions one after another urged people to explore more synthetic and comprehensive methods for earthquake prediction.The Lithosphere-Atmosphere-Ionosphere(LAI)coupling theory pays great attention to the processes taking place within the near ground layer of atmosphere.It has achieved great results recently,and can enlighten us about the nature of an earthquake's precursor.Based on the NCEP reanalysis dataset,this paper attempts to track the anomalies of the surface's upward long wave radiation flux(ULWRF),the temperature at the depth of 10cm～20cm below ground surface layer(BGL)and the air temperature at 2 meters above ground surface(AIR)around the time of the strong Wenchuan earthquake.Thermal anomalies were observed before and after May 12,2008,the time of the Wenchuan earthquake.Perhaps the thermal anomaly that occurred prior to the earthquake can be taken as indicators of the earthquake,but in view of the complexity of the earthquake phenomena,using thermal anomaly as a precursor should be done with caution.     

Neogene Through Quaternary Tectonic Reactivation of SW Iberian Passive Margin

Southwest Portugal, the Gulf of Cadiz and Morocco are under the potential threat of natural hazards linked to seismicity and tsunami generation. We report the results of two multi-channel seismic (MCS) surveys carried out in 1992 and 1998 along the continental margin and oceanic crust of SW Iberia. This MCS data set shows the evidence of the compressional deformation which involves both the continental and the oceanic crust of the study area. The area of deformation extends from the southern border of the Tagus Abyssal Plain to the Seine Abyssal Plain, encompassing the continental margin of SW Portugal. Most of the structures observed are probably related to a Mid-Miocene phase of Africa-Europe plate convergence. In this paper we discuss the recent advances on the identification of the tectonic structures that are still active and that may generate great earthquakes and tsunamis. The tectonic structures identified are located respectively at the Guadalquivir Bank, along the eastern border of the Horseshoe Abyssal Plain and along the southern continental slope of SW Portugal.BIGSETS Team: L. Mendes Victor, C. Corela, A. Ribeiro, D. Cordoba, J. J. Danobeitia, E. Grácia, R. Bartolomé, R. Nicolich, G. Pellis, B. DellaVedova, R. Sartori, L. Torelli, A. Correggiari, L. Vigliotti.     

Model for Paleoearthquake Recurrence Along Baying Segment of the North Margin Fault of Fanshan Basin in Hebei Province

Based on the measurement of faulted geomorphic surfaces,large trench logging and systematic chronostratigraphic sampling,we suggest that the total slip amount along the Baying segment of the north margin fault of Fanshan Basin since 90 ka B.P.is 34 m.Nine paleoseismic events occurred in the last 75 ka.Among them,the four events A,B,C,and D revealed by the large trench were dated at 28 ka,14 ka,7.5 ka,and 656 B.P.,respectiv eJy.The model for paleoearthquake recurrence along the segment may have two stages; in the stage from 90 ka to 14 ka B.P.,the "time-predictable model" is suitable,while in the stage from 14 ka B.P.to now,the "displacement-attenuation model" applies.     

基于BIM的地震灾后民用建筑重建工程施工成本控制方法

采用传统的成本控制方法,存在质量和成本无法同时优化、成本预测精确度低,成本控制效果不佳等问题,为此,提出基于BIM的建筑重建工程施工成本控制方法。采用灰色系统理论预测建筑施工成本具体面临的问题,以各期施工成本相关信息数据作为模型数据基础;结合BIM技术进行成本控制动态模型构建,在模型中引入可辨识矩阵设定成本各指标的相对重要度,进一步找寻施工成本各项指标间的关系,按其相互关系进行排序,得到子成本与总成本间的规则联系,并就规则制定控制策略,调整成本控制动态模型以实现施工成本的动态控制。实验结果表明,所提方法的成本预测精度始终在75%以上,成本控制结果与实际值的拟合度高达95%,相比当前方法具有更好的控制性能。     

河北矾山盆地北缘断层八营段的古地震重复模型

通过实测断错地貌面,开挖在探槽以及系统的地层年代采样,推断和揭露出矾出盆地北缘断层八营段９万年来总移量量为３４ｍ。经７．５万年来共发生过９次古位移事件。其中大探槽揭露的４次事件分别发生在距今：Ａ,２．８万年;Ｂ．１．４万年;Ｃ,０．７５万年和Ｄ,６５６年（？）左右。该段落古地震地重复模型分为两个阶段：９￣１．４万年间符合“时间可推测模型”;１．４万年来以来则为“位称衰减模型”。     

Active Features of the Hangingwall on the Listric Normal Fault Along the Southeastern Margin of Weihe Basin

Based on field observations and mechanic analysis,the authors think that synthetic faults,antithetic faults,and hangingwall cross-faults are formed on the piedmont alluvial-pluvial plain under the action of hangingwall blocks sliding downward and rotating along concave fault planes of the listric normal fault on the southeastern margin of Weihe Basin.The characteristics of different movements and expressions on the surface of these structures may be taken as the main marks for listric normal fault segmentation.     

Teleseismic Source Parameters of the Rigan County Earthquakes and Evidence for a New Earthquake Fault

Two medium-sized earthquakes occurred on 20 December 2010 and 27 January 2011 in Rigan County, Kerman Province, southeastern Iran. According to the dislocation grid search method results, the first event was nearly strike-slip including reverse component (strike 115°, dip 50°, and rake ?5°) whereas the second event had some amount of reverse component (strike 125°, dip 75°, and rake ?5°). Based on synthetic Green’s function deconvolution and aftershock distribution, the down-dip-propagated rupture migrated toward southeast districts with low population distribution, confirming the reason for low casualties. Meanwhile, the aftershock distribution indicates the existence of a new earthquake fault for which we suggest the name “Rigan earthquake fault.” However, the same aftershock distribution indicates that the second mainshock was inevitably triggered by the first one, most probably along the continuation of the Bam earthquake fault.     

存在一种震前超低频密度-应力波的更多证据

笔者曾指出存在一种震前由孕震区发出的地下构造中的超低频密度-应力波,而且这种波的性质与国外学者提出的"热力学弹性回跳"理论符合得很好,并列举了天文时纬残差、地下深部物质视电阻率和震前地壳突变性形变3个方面的观测证据来证明这种波的存在.我们进一步发现,我国地震工作者在对地震的长期观测和监视工作中,实际上已经获得了支持存在这种震前超低频密度-应力波的很多实测结果.大量实测数据既是这种波存在的证据,又是研究这种波的性质的第一手资料.本文将与震前超低频密度-应力波的特征符合得较好的实测资料择要列出,并与该波的特征相比较.分析表明,这些测量所反映的很可能就是这种震前超低频密度-应力波,因此也就反映了这种波的波源-震前缓慢而剧烈的地下介质扰动.     

唐山断裂带的板内重复地震识别及其滑动速率估算

华北地区以强烈的新构造运动、众多的板内地震、多发的破坏性地震著称.1976年7月28日发生在北京东约160km处的唐山7.8级大地震是历史上人员伤亡最为惨重的灾害之一.唐山断裂带是唐山大地震的主控断裂,由一系列互相平行的NNE向的走滑断裂组成,由于在构造表现和运动方式等方面存在明显的差异,基本上可划分为南、北两段.     

马尼拉海沟俯冲带板缘地震特征及衰减关系研究

俯冲带通常位于陆地板块与海洋板块或者海洋板块之间的交界处,地质构造复杂,地震活动频繁.在南海海域,马尼拉海沟俯冲带对中国海洋战略及近海重大工程的实施位置至关重要.在缺少实际地震数据的前提下,为分析马尼拉海沟俯冲带地震动及其衰减关系特征,通过采用随机有限断层法模拟该俯冲带地震动,分析地震动加速度时程及反应谱特点,同时分别...     

汶川地震后青藏高原东北缘中等地震活动特征分析

汶川地震后青藏高原东北缘地区发生了多次M_L≥4.0地震,本文利用甘肃数字地震台网的资料,采用CAP方法计算得到了31次M_L≥4.0地震的震源机制解,并对结果进行分析与讨论。研究表明:受汶川地震的影响,青藏高原东北缘区域应力场的调整过程使得中等地震分区、丛集活动,地震类型表现出明显的区域特征。31次中等地震的最大主应力方位显示,祁连山地震带优势方向为NE向,甘东南地区近EW向,表明区域应力场呈现局部性的特征。     

青藏块体东北缘中强地震前小震频度异常研究

1980年以来青藏块体东北缘共发生26次M_S5.0以上地震,其中22次在时间和空间上相对独立。 通过系统研究这22次中强地震前其邻区小震活动的增强现象,发现有17次中强地震前存在比较明显的小震增强现象。 虽然小震增强现象在多数中强地震前存在,但是利用小震活动的增强对未来中强地震的预测比较困难。 文中结合青藏块体东北缘小震活动的特点,尝试提出根据小震活动空间格局是否改变统计小震频度的方法,并且进行了初步的应用。 结果表明: 利用新方法统计小震的频度更能突出中强地震前的小震频度异常,并且中强地震前的小震频度异常幅度受空间范围大小的影响不大,能够有效的提取青藏块体东北缘中强地震前的中短期异常指标。     

旱涝周期和海震调温假说的新证据

据中新社兰州10月21日电,中国科学院寒区旱区环境与工程研究所蓝永超研究员根据代表黄河上游流域径流动态变化的唐乃亥水文站1920年至2004年的径流系列统计资料,以及此间数十个气象站四十余年的降水观测数据,分析得出的初步结论显示,从上世纪20年代初到90年代,黄河大体上经历了5个枯水期和4个丰水期。每个丰、枯水期段持续的时间长短不一,枯水期持续时间为4~15年,平均为9年;丰水段持续时间为7~14年,平均为9.25年。总体上黄河上游每个丰、枯水周期平均持续时间基本相同,一个完整的丰枯循环周期大约在18年左右[1]。18.6年是典型的潮汐周期。月…     

四川盆地及其西部边缘震区基底磁性界面与地震的研究

在对四川盆地及其西部边缘震区航磁资料进行分析研究的基础上，依据频率域磁性单界面反演方法对航磁异常进行了数据处理，求取了基底磁性界面的定量埋深，结合区域构造特征，地热分布及板块运动对地震的孕育环境进行了综合研究和讨论。     

The Predictability of Large Earthquakes: Evidence from an Analogue Model of Earthquake Rupture

—The recurrence behaviour of large earthquakes, in several tectonic settings, has been explained by simple models of stress accumulation and release which assume that the fault stress state is solely a function of the far-field tectonic strain rate. However, the limited dataset of large event recurrence intervals has been a major obstacle to the verification of these and other models. We present the results from a simple analogue model of earthquake rupture and stick-slip which displays power-law frequency-size statistics and involves many cycles of large events. We show that, despite the macroscopic homogeneity of the model, large events do not conform to simple deterministic time- or slip-predictable patterns. However, when the recurrence intervals for large events are divided by the median recurrence interval, the normalized data are composed of two distinct lognormally distributed populations. One population is characterized by events which are strongly clustered in time with relatively short recurrence intervals and low moment release, the other by events which are weakly clustered in time with median-sized recurrence intervals. It is suggested that the long-term recurrence behaviour of large earthquakes, whilst being non-deterministic, may be modelled by a well-defined statistical distribution of recurrence intervals.     

Current Activity Characteristics of the Fault Zone Along the Northern Margin of West Qinling Range Revealed by GPS Measurementl

The fault zone along the northern margin of West Qinling Range is a major active fault zonein the key seismic monitoring area in the southeastern part of Gansu Province.In order tostudy the current activity characteristics of this fault,GPS monitoring network has beenarranged along both sides of the fault and 3 measurements have been made from 1996 to1998.The result indicates that obvious differential movement exists along the north and southsides of the fault and the eastward movement on the south side is 3.8mm/a larger than thaton the north side.In the GPS network,the shortened side is generally in the trend of EW andthe extended side is basically NW to SE.The principal compressional stress trend in this areais about EW and the sinistral motion is obvious in the eastern part of the fault(nearWushan).The measured results also indicate that the displacement rate has decreased by50% and the compressional strain has increased by 100% as compared the data of 1997～1998 with those of 1996～1997,which shows t