Distribution of empirical recurrence intervals for segment-rupturing earthquakes on active faults of the Chinese mainland

IntroductionInassessingtheprobabilitiesoftime-dependentandlong-termseismichazardsforsegmentsofactivefaults,itisnecessarytohavetheprobabilitydensity,f(O,fordescribingtherecurrenceintervaldistributionforsegment-rupturingearthquakes.Fromf(nandthefollowingequation,theconditionalprobability,pc,whichincreaseswiththetime,Te,elapsedsincethelatestearthquake,isabletobecalculated(Nishenko,Buland,1987,WorkingGrouponCaliforniaEarthquakeProbabilities,1995;Wen,1995,1998)fwhereATisthetimeintervalforthefor…     

Grouping occurrences being the fundamental feature of the strong earthquakes in Chinese mainland

ＧｒｏｕｐｉｎｇｏｃｃｕｒｒｅｎｃｅｓｂｅｉｎｇｔｈｅｆｕｎｄａｍｅｎｔａｌｆｅａｔｕｒｅｏｆｔｈｅｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓｉｎＣｈｉｎｅｓｅｍａｉｎｌａｎｄＱｉｎ－ＺｕＬＩ（李钦祖）；Ｌｉ－ＭｉｎＹＵ（于利民）；Ｊｉ－ＹｉＷＡＮＧ（王吉易...     

汶川地震同震形变场对川滇地区主要活动断裂地震发生趋势的影响

以所建立的川滇地区主要活动块体及其周边断裂带的模型和前期利用GPS及水准资料反演所得到的断裂带长期运动速率作为基础,将汶川地震引起的同震错动量加入到三维断裂几何模型中,计算出汶川地震大范围的同震形变场,然后基于该同震形变场和活动断裂三维几何模型反演了各条断裂对该同震形变场的反映,并通过与各断裂带长期运动速率对比,得到了汶川地震对川滇地区各主要活动断裂带发震趋势的影响．结果表明,在汶川地震引起的同震形变场作用下,在川滇交界东部地区,龙门山断裂带南西段地震危险性提前了305a,鲜水河断裂带南东段大致提前了19a,安宁河断裂带和则木河断裂带分别提前了21a和12a,大凉山断裂带北段和南段分别提前了9.1a和18a,马边断裂带的地震危险性则提前了51a;对川滇交界西部的丽江——小金河断裂带南西段、怒江断裂带、龙陵——澜沧断裂带、南汀河断裂带、中甸断裂带等断裂带地震的能量积累也有促进作用;相反在鲜水河断裂带北西段、小江断裂带等历史地震频发的断裂带上,地震危险性具有一定的减速作用．      

城市活动断层探测的实施和常见技术问题

本文通过对我国二十余个大城市的活动断层探测与地震危险性评价项目实施的实践总结,讨论了探测中常见的一些关键技术问题,探讨如何根据探测深度选择不同探测技术方法;深浅组合探测;多方法综合探测应用和由粗及细提高探测精度;以及组织实施过程中的一些可能问题和解决思路。为近阶段将我国较广范围内开展城市活动断层探测与地震危险性评价工作作参考。     

Assessment of strong earthquake risk in the Chinese mainland from 2021 to 2030

The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland. Based on the strong earthquake recurrence model, the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault, which are adopted from relevant studies such as seismological geology, geodesy, and historical earthquake records. Based on the long-term predictions of large earthquakes throughout the world, this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap, motion strongly locked, sparse small-moderate earthquakes, and apparent Coulomb stress increase. This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland. The present loading rate of each fault is first constrained by geodetic observations; the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.     

Recurrence characteristics of late-quaternary strong earthquakes on the major active faults along the northern border of Ordos block

Through study on trenches, analysis of recurrence characteristics and recurrence interval cluster/gap of strong earthquakes along the major active faults on the northern border of Ordos block, we found 62 paleoearthquakes that occurred in the late Quaternary, including 33 earthquakes occurring in the Holocene. The recurrence characteristics of the paleoearthquakes are different at three levels, segments, faults, and fault zones. The strong seismic sequence on the independent segments is mostly characterized by long- and short-interval recurrences, while that on the faults and in fault zone is characterized clearly by random and cluster recurrences. Results of the moving window test indicate that the probabilities of "temporal cluster or gap", caused by random coincidence as opposed to intersegment contagion, are 64% and 70% for the Serteng piedmont fault and for the south-border fault of Wula Mountains, respectively, no clear interaction among the segments of each fault; while the probability is 26.8% for the whole fault zone, suggesting a clear interaction among the faults of this fault zone. These recurrence characteristics may imply an effect of the entire block motion on the recurrence of strong earthquakes. Moreover, the elapsed time for the Wujumeng Pass-Dongfeng Village segment of Serteng piedmont fault and the Tuzuo Banner-Wusutu and the Hohhot segments of Daqingshan piedmont fault has exceeded the average recurrence interval, hence these three segments may be the possible places for future strong earthquakes.     

张北地震区的断裂构造特征

1998年1月10日张北6．2级地震发生在张家口坝上地区，震区被中、上新世溢流玄武岩覆盖，第四系地层0－3m。电磁波遥感探测结果表明，张北震区存在NEE、NWW和NE向三组断裂。野外调查证实NWW向的小水泉－－满井断裂，尚义县套里庄乡东水泉南北向断裂和赤城－－尚义大断理解的东西向次级断裂都明显错断中、上新世玄武岩及其夹层。热释光（TL）年龄测定结果表明，这三条断裂的最新活动时代分别为16．7万年，20．3万年和14．3万年。张北地震发生在NEE、NE和NWW向三组断裂的交汇区附近，NWW向的小水泉－－满井断裂是发震断裂。     

An overview on shallow strong earthquake activity and earthquake live losses of Chinese mainland in the centenary from 1901 to 2001

Introduction It is well known that China locates in the southeastern part of Eurasian Plate, which subjects to the action of westward subducting of Pacific Plate and Philippine Sea Plate, and northward col- lision of Indian Plate. So China is a country with strong seismicity. There are two kinds of earth-quake activities in China. In the Chinese mainland most of the earthquakes belong to the intraplate ones, and in Taiwan of China belong to interplate ones. According to the statistics 9…     

The structure features of stick-slip mechanism of the strike-slip earthquake generating structure in the interior of the Chinese mainland

ＴｈｅｓｔｒｕｃｔｕｒｅｆｅａｔｕｒｅｓｏｆｓｔｉｃｋｓｌｉｐｍｅｃｈａｎｉｓｍｏｆｔｈｅｓｔｒｉｋｅｓｌｉｐｅａｒｔｈｑｕａｋｅｇｅｎｅｒａｔｉｎｇｓｔｒｕｃｔｕｒｅｉｎｔｈｅｉｎｔｅｒｉｏｒｏｆｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄＷＥＮＬ...     

塔里木盆地主要断裂的地球物理特征及与天然地震的关系

新疆塔里木盆地是中国最大的内陆盆地,地质构造上是周围被许多深大断裂所限制的稳定地块.塔里木盆地的地震发生是盆地与造山带耦合俯冲的结果,与盆地周缘的活动性深大断裂相关,是盆地扩张使盆地与山脉的结合带不断受到挤压产生脆性破裂引起的,构成盆地中部为稳定区、而盆地周围山脉为地震频繁区的格局.塔里木盆地的活动断裂主要发育于山体与盆地的过渡地带,而近两年这6次规模比较大的地震也都发生在西昆仑和南天山的山前俯冲带,据以往统计资料,塔里木盆地内所有地震数据中的85%是分布在塔西南和西南天山的南缘区域.本文通过分析认为,塔里木盆地地震的发生与大型的断裂构造相关.断裂构造在重力、磁力等地球物理场上特征明显,深部结构又容易被大地电磁测深、地震测深等物探方法揭示.通过综合地球物理方法,可以有效地研究断裂的平面展布特征及深部结构,对于研究天然地震带的展布和地震发生机制,具有一定的意义.     

2001年昆仑山口8.1级巨震后中国大陆、云南地震趋势研究

分析研究了2001年11月14日昆仑山口8．1级巨震对中国大陆云南未来几年地震趋势的影响，指出巨震后6年大陆可能仍然处于地震活跃期，其间大陆西部发生7．0级以上大震可能性较大；受2000－2001年欧亚带东南段大震活动过程及巨震调整影响，未来1－3年云南省可能进入新的活跃期，6．5级以上强震危险性增加。     

Crustal block rotations in Chinese mainland revealed by GPS measurements

We simulate GPS horizontal velocity field in terms of rotations of crustal blocks to describe deformation behavior of the Chinese mainland and its neighboring areas.31 crustal blocks are bounded primarily by~30 Quaternary faults with distinct geometries and variable long-term rates of<20 mm/a,and 1 683 GPS velocities were determined from decade-long observations mostly with an averaged uncertainty of 1?2 mm/a.We define GPS velocity at a site by the combination of motion of rigid block and elastic strain ind...     

Statistical features of aftershock distribution size for moderate and large earthquakes in Chinese mainland

Based on data of earthquake sequences with MS≥5.0 in Chinese mainland from 1970 to 2004,for different se-quence types and different rupture modes of the main shock,the relationship between aftershock distribution size Rand the magnitude of the main shock M0 has been studied statistically.Considering the rupture mode of the mainshock,we give the quantitative statistical relationships between R and M0 under 95%confidence level for differentsequence types.Qualitatively,lgR,the logarithm of the aftershock distribution size,is positively correlative to theM0,but the data distribution is dispersed.Viewing from different sequence types,the correlation between R and M0is very weak for isolated earthquake type(IET)sequence,R distributes in the range from 5 to 60 km;For main-shock-aftershock type(MAT),lgR is positively correlative to M0;For multiple main shock type(MMT),the core-lation between lgR and M0 is not very obvious when M0≤6.2 and R distributes in the range from 5 to 70 km,whileit shows a linear correlation when M0≥6.3.The statistical results also show that the occupational ratios of differentsequence types for strike-slip and oblique slip are almost the same.But for dip-slip(mostly are thrust mechanisms),the ratio of MAT is higher than that of IET and MMT.Comparing with previous results,it indicates that,when M0is large enough,R is mainly determined by M0 and there is almost no relationship with the rupture mode of themain shock.     

中国大陆地壳运动与汶川MS8.0级地震孕育的关系

根据网络工程的GPS站点观测资料,计算相对中国大陆整体1999～2007年的趋势运动速率和2004~2007年的动态运动速率,用青藏亚板块和华南亚板块的参数计算龙门山断裂带的活动参量,研究了中国大陆运动场和其变化,分析了地壳运动场的特征与汶川M_S8级地震的孕育关系.结果揭示出：现今地壳的运动分区与地质新构造单元基本一致,显示现代地壳构造活动是新构造运动的继承和发展;中国大陆地壳运动的动力主要与印度板块、太平洋板块与欧亚板块的相互碰撞俯冲产生的作用力有关.汶川M_S8级地震的发生,主要是由于印度板块对青藏亚板块的向北推挤、产生侧向运动,致使龙门山断裂带遭受挤压产生能量积累所致.2004～2007年的地壳动态运动,使龙门山断裂带走滑活动加强,从稳定的压应变积累状态转入了剪切作用下的易活动状态.     

利用GIS研究延怀盆地地震与断裂关系

通过Arcgis catlog建立延怀盆地地震和活动断裂基础数据库,运用GIS软件环境的缓冲区、空间叠加及统计等分析方法,对延怀盆地内部地震活动与活动断裂关系进行研究,结果证明：中小地震活动主要沿怀涿盆地北缘断裂和延矾盆地北缘断裂分布;约83.7%的地震发生在以10 km为半径的断裂缓冲区内;在正断层缓冲区内,单位地震数较高。结合活动构造特征,分析认为,延怀盆地在全新世以来受拉张应力场控制作用,中小地震活动集中分布在盆地一侧,且靠近控制盆地的主控边界断裂。     

Earthquake recurrence on whole active fault zones and its relation to that on individual fault-segments

IntroductionEarthquake recurrence models established on activity behaviors of strong earthquakes are the bases of long-term earthquake prediction, seismic risk zonation, and seismic hazard assessment. A lot of studies have been carried out on earthquake recurrence behaviors for specific seismogenic sources or fault-segments, and a series of empirical recurrence models have been proposed, such as the time-predictable model and the slip-predictable model for earthquakes repeated at the previous …     

中国大陆地震条带统计特征分析

对中国大陆具备相对完整资料的327次M≥5.0地震,分5个工作区进行了统一要求的地震条带图像扫描,发现96次中强震前存在条带图像,约占研究地震总数的29％.其中震前有条带地震与研究地震的比例分别为:华北地区30％,华东南区29％,川滇地区41％,青藏高原西北缘24％,新疆地区16 ％.中强震前出现条带比例最低的是新疆,...     

Multi-scale analysis of earthquake activity in Chinese mainland

IdentifyingtheactiveandinactiveperiodofearthquakesinChinesemainlandisofgreatimportanceforguid-ingmid-shortterm,especiallyshortterm,earthquakeforecast.Thisisanindispensablestepforstudyingearth-quakepredictioninourcountry.Nowanintegratedsetofconceptsandmethodsforgeneraltrendpredictionofearthquakeactivityhasbeendeveloped.BasedontheChineseearthquakedatasincethebeginningofthe20thcentury,somestatisticalmethodshavebeendevelopedtoanalyzeoccurrencefrequencyandenergyreleaseofearthquakes,distinguishacti…     

鄂豫皖交界地区地震地质背景与中强地震复发特征的研究

鄂豫皖交界地区位于东大别山西部，历史中强地震(M≥43/4)主要发生在土地岭-落儿岭及商城-麻城断裂带上，且“互动”和“连动”的特征较为显著。根据这一特征，在研究东大别山区域地质、地壳结构、断裂活动及地震构造应力场特征的基础上，可将鄂豫皖交界地区的中强地震作为秦岭-大别山活动地块中的次级地块的整体活动来看待。该区历史地震活动整体表现为丛集特征，而主要发震断层(土地岭-落儿岭断裂)的历史地震活动则具有相对较好的准周期性。地震复发周期研究提示，该地块近期发生M≥5．0左右地震的危险性较大，而霍山-六安地区为未来发生中强地震的主要危险区。     

中国大陆Lg波衰减成像

本文利用2009—2019年间中国大陆固定台站记录的宽频带地震波形数据, 采用反双台法, 获得了约36万个台站对的Lg波Q值, 并反演得到了中国大陆Lg波的衰减模型.结果显示, 中国大陆Lg波衰减的Q值结构存在显著的横向非均一性.青藏高原、渤海湾盆地以及祁连山造山带等构造活动块体展现出明显的地壳低Q值强衰减特征, 而华南块体、鄂尔多斯盆地以及塔里木盆地等相对稳定的地区则呈现地壳高Q值弱衰减特征.Lg波衰减与构造活动强度、松散沉积物、地下流体或部分熔融以及地质块体结构等因素密切相关.渤海湾盆地的强衰减主要由上地壳巨厚的松散沉积物和较高的地壳温度导致.青藏高原和祁连山造山带的地壳强衰减主要归因于现今活跃的构造活动、复杂的断裂系统和地质结构以及富含地下流体甚至是部分熔融等因素.华南造山带和大兴安岭地区的地壳弱衰减特征可能与侵入岩冷却形成高强度的结晶基底以及古老造山带地壳构造趋于稳定相关.