台湾地区强震发生的构造环境与地震活动性分析

台湾中部造山带前缘呈现为一弧形逆冲构造体系 ,每个弧形带分别由多个不同尺度但各自独立的次级弧形构造组成 ,而每一个弧形构造都有其各自独立的几何学、运动学和动力学特征 ,是典型的褶皱 -逆冲带 ,但同时各个次级弧形构造间却又有自相似特性。在对台湾中部地区弧形逆冲构造体系的空间位置与地震活动间的关系分析基础上 ,归纳出中部弧型逆冲地震带的地震活动特征 ,以台湾东西地震区的构造划分和北部、中部与南部不同的弧陆构造现象 ,描述了台湾地区的近代地震活动 (190 0年以来的 10 0年间 )与现代地震地质构造的关系     

台湾东,西地震带活动高潮期划分区别及其特征

对处于环太平洋地震带上频繁发生地震的台湾地震带如何划分活动高潮期,是一个值得认真探讨的问题。本文根据有仪器记录以来的80年(1901-1980)台湾地震资料,尝试提出一种划分活动高潮期的能量基准水平,结合地震时间分布、空间分布和强震序列等特征,确认出台湾东、西带的活跃期和平静期,分析了其活动规律。尤其通过比较台湾东带两个活跃期最后一个活跃时段,发现在最大震级和活跃持续时间的量级上,空间强震迁移的紊乱和能量释放出现“回光返照”现象等方面有惊人的相似性,反映了台湾地壳构造运动内在周期规律,这对预测台湾地震活动将是十分有意义的。文中最后比较了台湾东、西地震带地震活动特征差异,从板块构造活动观点来看,这种差异可能同台湾东、西带地震分属于板缘和板内地震有关。     

台湾100年地震活动图解

台湾地震的仪器观测始于1898年，到1997年地震目录中已累积列出的地震约17万个。在世纪之末回顾这100年地震活动性情况是件有趣的事情。本文将分别用不同的绘图技巧来阐述这些地震的分布情况，进而分门别类地揭示它们发生的实质。分析中一些以前没有注意到的地震分布图象得以揭示。无庸质疑，台湾的地震是由该岛周围的构造运动所激发的。我们试图通过地震分布图找到地震活动性与构造的关系。采用由不同构造的相互作用所驱动的4个地震体系来描述它们特定的地震活动图象。通过对地震活动分布的仔细分析，许多有趣的构造运动特征得到了解释。另外，我们也希望这些已经得到充分论证的地震图能有其他用途或被用于大众科学教育。     

1994年9月16日台湾浅滩7.3级地震发震构造的讨论

从台湾海峡与台湾浅滩的地貌特征、区域构造格局、海峡盆地形成历史、深部构造与断裂构造、震源机制解以及地震活动等方面论述了台湾浅滩７．３级地震的发震构造,认为北东东向澎湖－北港隆起南侧断裂（义竹断裂）是该地震的发震构造。     

新沂-泗县地震危险区地震活动和地震构造

运用深浅部构造对比研究、构造解析技术，结合历史地震资料、中强震观测资料分析、地震活动性分析结果，探讨中强震过渡区地震构造环境和地震韵律的研究途径，圈定出新沂—泗县地震危险区。对该危险区进行立体综合剖析，推演出未来中强震发生的空间部位，并预测了该区未来可能发生地震的震源深度、震级、地震长轴衰减方向、地震复发间隔等参数。     

中国大陆地震构造带的初步划分及其应用

本文依据深部地球物理场、区域大地构造、地表活动断裂、地震活动等，划分了中国大陆的地震构造带，同时分析了地震构造带的活动特征和孕震构造条件，在此基础上，具体地把地震构造带的概念应用于地震危险区分析之中，探讨了地震危险区及地震前兆异常与地震构造带的关系，本文提出以地震构造带研究作为地震监测和预报工作的基础，将地震构造带作为系统性的活动构造条件应用于地震危险区划分之中。     

新疆地震构造带及其特征

本文根据地震活动特征,块体活动性质、地质构造特征、深部构造和震源力学,将新疆地震构划分为五个强震构造带。分别讨论了各带的地震活动和构造运动特征     

地震活动周期的谱分析

本文通过谱分析方法,探讨了台湾东带、台湾西带和泉州—汕头地震带地震活动的周期性。结果表明,这三条地震带均隐含了2—3种周种;三条地震带的卓越周期分别为17、30和335年。即由板块冲撞部位向大陆内部,地震活动周期由十几年增加到几百年。这一现象可能反映了板块活动及其对大陆内部作用的某种规律。深入研究这三条地震带的地震活动规律,有可能揭示板缘与板内地震之间的内在关系。     

海域活动断裂探测和古地震研究

我国地震活动强烈 ,不仅在陆域的不同地震区带内有强烈的地震活动 ,而且在不同海域也有强震发生 ,如在渤海、南黄海、台湾海峡和北部湾等海区均发生过多次 6～ 7 级地震 ,有的海域地震的重复性很高 ,如渤海及邻近海域自公元 1 54 8年以来已先后发生过 4次 7级以上地震 ,南黄海在最近 50 0年内已发生过 1 0次以上 6～ 7级地震 ,台湾海峡在 1 7世纪和2 0世纪先后发生过多次 7级以上地震。近 40年来 ,我国对陆域活动构造和地震构造的调查和研究取得了很大进展 ,尤其是最近 2 0年来 ,由于定量活动构造学的发展 ,对陆域大地震发生的构造条件及…     

华北地区M≥6地震活动方式的探讨

分析了华北地区1966年以来发生的M≥6地震和相关历史地震所处的构造环境、空间位置,并依据华北地区北东向构造发育等特点,把1966年以来发生的M≥6地震及相关历史地震划分为3个不同方向的5条地震构造带,第1,2,3条为北东向地震构造带,第4条为1969年以来发生的5次地震形成的可能为一条北西向的地震构造带,第5条为1975年以后发生在φN39°～φN42°线之间的地震形成的东西向地震构造带(阴山、燕山东西向地震构造带),这表明,地震具有成带活动和成组活动的特点.     

台湾岛对气流扰动的影响

本文根据一个三维气流过山的模型,用数值快速傅里叶变换方法,讨论理想东北季风气流经过台湾岛产生的扰动气压场、扰动垂直速度场和水平流场.经与实际东北季风下台湾岛的气候特征进行比较,结果令人满意.     

台湾9.21集集地震考察兼论强震发震断层

1999年9月21日,台湾中部山麓带发生了M7.3的大地震,震源深度为8km,财产损失及人员伤亡是百年来台湾许多地震中损失及伤亡最大的1次,其震级也是台湾本岛陆上所发生的地震级别最大的。震源机制属低角度逆冲断层成因,余震在平面上围绕着北港高基底作半圆状分布,在垂向上,则分布在逆冲断层的上盘。与此相应,地面变形及上部结构物的破坏,以车笼埔发震断层上盘最为激烈,下盘几乎不受影响。此外,地震断裂的北端,水平位移量高达9.8m,垂直抬升达10m,比主震区要大;其地面加速度峰值,亦高达水平为502gal,垂直为519gal。这些特点表明,地震是受到地下深处侏罗型叠瓦状构造的控制。此外,3个诱发地震中心均受当地的地质构造与地貌条件的控制。文中还叙述了震害及工程结构物破坏的特点,尤其是水工结构物的震害     

Crustal movement and deformation in Taiwan and its coastal area

Introduction Both Taiwan Island and Chinese mainland belong to Eurasian plate in geological structure. And the nearest distance between Taiwan Island and Fujian Province, which is located on the opposite coast, is only 130 km. Although there are high-precision GPS networks in both Taiwan and Fujian Province, joint GPS measurement cannot be made directly because of the inconvenient contact due to the strait between them. However, the GPS networks arranged on b…     

Study on the transverse structures across Taiwan Strait

The mountain ranges are almost NE- or NNE-trending in mainland and Taiwan island across the strait. But a number of correspondent transverse structures across Taiwan Strait have been identified on the basis of morphology, surface structure, deep seismic survey and gravity field etc. Moreover, it is inferred from the square or/and rectangular shape of the isoseist maps of 8 M≥ 6 earthquakes occurring in the western foothill plain of Taiwan that there is an apparent segmentation of the Taiwan Island along the N-S orientation. This has been verified from the GPS’s results of the ground motions measured during the Chi-Chi earthquake in 1999. As a matter of fact, the transverse structures within the Taiwan Island could be correlated with more salient NW- and EW-trending structures in the mainland of Fujian than in Taiwan. The investigation of the transverse structures across Taiwan Strait is conducive to realizing the geology within the strait. Hence, the tectonic sketch map of the strait as well as mainland and island drawn in this context shows NW- and EW-trending structures for the study area.     

Migration of volcanism with time in the Marquesas Islands,French Polynesia

Samples from five islands of the Marquesas Island chain (southeast Pacific Ocean) have been dated by the K-Ar method and exhibit a northwest to southeast volcanic migration rate of 9.9 cm/yr. This movement is in the same direction but of intermediate magnitude to results from the Austral Island chain (lower rate) and the Hawaiian Island chain (considerably higher rate). The rate of migration of volcanism in the Marquesas Islands is consistent with the model of rigid Pacific plate movement over a fixed “hot spot” or mantle “plume” provided that the pole of rotation for the Pacific plate for the last 5 my is located near 55°S, 170°E.     

What controls the extreme flow through the Kerama Gap: a global HYbrid Coordinate Ocean Model reanalysis point of view

Ocean Dynamics - The temporal variability of volume transport from the North Pacific Ocean to the East China Sea (ECS) through the Kerama Gap (between Okinawa Island and Miyakojima Island—a...     

Dissolved barium as a tracer of Kuroshio incursion in the Kuroshio region east of Taiwan Island and the adjacent East China Sea

From May to June 2014, the geochemical characteristics of dissolved barium(Ba) in sea water and its influx from the Kuroshio into the East China Sea(ECS) were studied by investigation of the Kuroshio mainstream east of Taiwan Island and the adjacent ECS. This allowed for the scope and extent of the Kuroshio incursion to be quantitatively described for the first time by using Ba as a tracer. The concentration of Ba in the Kuroshio mainstream increased gradually downward from the surface in the range 4.91–19.2 μg L.1. In the surface layer of the ECS, the Ba concentration was highest in coastal water and gradually decreased seaward, while it was higher in coastal and offshore water but lowest in middle shelf for bottom layer. The influx of Ba from Kuroshio into the ECS during May to October was calculated to be 2.19×108 kg by a water exchange model, in which the subsurface layer had the largest portion. The distribution of Ba indicated that Kuroshio upwelled in the sea area northeast of Taiwan Island. The north-flowing water in the Taiwan Strait restrained the incursion of Kuroshio surface water onto the ECS shelf, while Kuroshio subsurface water gradually affected the bottom of the ECS from outside. The results of end member calculation, using Ba as a parameter, showed that the Kuroshio surface water had little impact on the ECS, while the Kuroshio subsurface water formed an intrusion current by climbing northwest along the bottom of the middle shelf from the sea area northeast of Taiwan Island into the Qiantang Estuary, of which the volume of Kuroshio water was nearly 65%. Kuroshio water was the predominant part of the water on the outer shelf bottom and its proportion in areas deeper than the 100 m isobath could reach more than 95%. In the DH9 section(north of Taiwan Island), Kuroshio subsurface water intruded westward along the bottom from the shelf edge and then rose upward(in lower proportion). Kuroshio water accounted for 95% of the ocean volume could reach as far as 122°E. Ba was able to provide detailed tracing of the Kuroshio incursion into the ECS owing to its geochemical characteristics and became an effective tracer for revealing quantitative interactions between the Kuroshio and the ECS.     

华南岛弧系统的近期活动

在新的地震活跃期中，台湾海峡７．３级地震和北部湾两次６级地震的发生，标志着华南弧岛系统相应了进入了强烈活动阶段，它们虽然都受控于太平洋板块（包括菲律宾海弧块）的西向挤压，但由于块体运动的主支与被动，作用力量级的不同和地质构造的差异而存在强度和诸多参数的差别。尽管如此，两处地震无疑都属于板内地震，利用它们和板缘地震的关系，可宏观地观测华南大陆的地震活动趋势。     

Current monsoon conditions of river runoff and groundwater formation in west pacific regions: Kamchatka Peninsula and Taiwan Island

The dynamics of climate and runoff characteristics are studied in the territories of Kamchatka Peninsula and Taiwan Island, which are situated in the influence zone of monsoon circulation. Long-term variations in the temperature, precipitation, and runoff are examined in Kamchatka and Taiwan for the weather and gauging stations with the longest observation series to analyze new climate conditions of water resources generation.     

An altimetric transport index for Kuroshio inflow northeast of Taiwan Island

The Kuroshio inflow northeast of Taiwan Island plays an important role in the heat and nutrient balances over the East China Sea(ECS). Based on merged satellite altimeter data and the PCM-1 mooring observation at the East Taiwan Channel(ETC), the study employs a correlation iteration scheme to find the optimal transport index for the Kuroshio inflow. The sea level difference with the highest correlation to the ETC transport is across the ECS shelf break rather than along the PCM-1 line. The counter-intuitive result is caused by large signal noise and poor track coverage of altimeters near the Taiwan coast. The optimal altimetric index is highly correlated with the two-year in-situ measurements as well as the ten-year output of the global assimilation model. It serves as a better estimator of Kuroshio inflow than those using tidal gauge data, and helps pinpoint a 5 cm mismatch of mean sea level in the Keelung tidal record. The mean transport of Kuroshio inflow based on the twenty-year altimetric index is 20.55 Sv with a standard deviation of 3.05 Sv. Wavelet spectrum of the index reveals that semi-annual period dominates the Kuroshio variation northeast of Taiwan Island.