※ [本文得原作者同意转录自 TY_Research 看板并做局部修改] （注）这篇其实提到一个有趣的现象，看似不大的压力变化对地震的发生与否似有 一定程度的影响。事实上在世界其他地方也有发现类似的表徵，如喜马拉雅 山地区的地震发生与季节有一点程度的关连，後来发现有可能是地下水位变 化影响板块负重所产生的影响..这种第一尺度的观察在未来几年之内应该还 会有更多的例子，到时很多原本不清楚的现象或许会得到更多了解答。 发信人: [email protected] (永远的追寻), 看板: TY_Research 标 题: Re: [新闻] 台湾地区的台风可避免灾难性的地震吗？ 发信站: casamia (Fri Jan 12 11:53:17 2007) 转信站: ptt!Group.NCTU!grouppost!Group.NCTU!casamia ※ 引述《[email protected] ()》之铭言： : 预防重於治疗--台湾地区的台风可避免灾难性的地震吗？ : http://www.tam.gov.tw/news/2007/200701/07010403.htm : 来源：台北天文馆天文新闻 : 美国华盛顿卡内基研究所（Carnegie Institution）Alan Linde、Selwyn : Sacks及中研院地科所研究人员曾在12月中旬的自然（Nature）期刊中发表 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Nature并没有这篇论文.... 这个研究是在十二月AGU（美国地球物理联合会） 研讨会中（由中研院的刘启清研究员）口头发表， Nature网站有一个专门整理重要研讨会内容的部落格， 所以被Nature部落格写出来。 （有台湾研究人员参与的研究，报导里却没有提到名字，这样有点令人难过...） : 论文指出：台风可能会引发地震。这篇报告并在自然期刊网站的部落格中 : 引发讨论。 : 台湾位於太平洋板块、菲律宾板块和欧亚大陆板块的交界，其中菲律宾板 : 块与太平洋板块均为比重较大的海洋地壳，且向西移动，与比重较轻的欧 : 亚大陆板块挤压後，会向下沈降，隐没在欧亚大陆板块之下，而欧亚大陆 : 板块受挤压部分上升形成台湾本岛，为「聚合型」的板块边界。由於处在 : 如此特殊的地方，台湾因而拥有各式各样丰富的活跃地质风貌，成为地质 : 学者的研究天堂。 : http://www.tam.gov.tw/news/2007/200701/typhoon.jpg : Linde与中研院地科所、台湾地震科学中心等机构的研究人员於2003年开始 : 合作进行「板块边界观测台计画（Plate Boundary Observatory - Taiwan， : PBO-T）」，在台湾东海岸设置了3部应变观测器（strainmeter），或利用 : GPS等仪器，观察台湾邻近区域活跃的板块边界的各项变化，试图找出为何 : 台湾东海岸板块边界为何发生大规模地震的频率不若其他类似地方的原因。 : 经过多年观测後，研究人员提出一个全新的理论，认为由於台湾经常会有台 : 风通过，台风为大气压力较低的地方，因而促使台湾陆地压力减轻，使得断 : 层滑动速度加快；不过虽说「加快」，其实以人的观点而言还是很慢，没有 : 什麽危险性。因此在本质上，热带风暴可能会引起许多小型地震，并因小型 : 地震不断发生，让板块边界上的能量不致於累积得过大，因而鲜少发生大规 : 模的危险性地震。 : 虽然这个点子很不错，不过似乎并不适用在全球。例如美国墨西哥湾就并非 : 位在板块边界这种高危险地震带上，所以飓风的发生并不会对地震有何影响。 : 而日本的地质条件与台湾差不多，就对这个台风引发小地震、阻碍大地震发 : 生的想法颇感兴趣，也打算加入相关研究。 : 资料来源： : [台北天文馆] : http://www.tam.gov.tw/news/2007/200701/07010403.htm : [板块边界观测台计画（Plate Boundary Observatory - Taiwan，PBO-T）] : http://www.earth.sinica.edu.tw/research/research.htm : [自然(NATURE)期刊的部落格] : http://blogs.nature.com/news/blog/2006/12/agu_do_typhoons_cause_earthqua.html : 　 Nature部落格中的原文是（中文报导似乎是直译这篇文章） Sometimes a couple of scientific instruments, in just the right place, can trigger all sorts of new investigations. Take the three strainmeters that the Carnegie Institution of Washington placed along the eastern coast of Taiwan starting in 2003. Alan Linde and Selwyn Sacks, working with their Taiwanese colleagues, were trying to figure out why the area didn't seem to have as many large earthquakes as it should - being located on the boundary of two tectonics plates and all. Instead, the scientists arrived at a whole new theory. Typhoons passing over the island, the team argues, release pressure on the land and allows the faults there to slip at very high, but very slow and non-dangerous, rates. In essence, tropical storms enable a lot of very small earthquakes and prevent the large and dangerous ones. It's a very cool concept that, unfortunately, may not apply other areas of the world. The US Gulf Coast, for instance, is not at high risk of killer earthquakes and thus could conceivably be saved by hurricanes. But Japanese scientists are interested in extending the work to their country, Sacks told me at his poster session this morning. "This is a big surprise for us," he said. "It's the kind of finding that is driven by data, not by insight." 这是这个研究在AGU研讨会的摘要： As part of a cooperative program between Academica Sinica, Taiwan, and Carnegie Institution of Washington a small network of Sacks-Evertson strainmeters has been installed in eastern Taiwan, starting in 2003. The program focuses on providing data that will complement GPS data sets in aiding improved understanding of the rapid and complex tectonic deformation of the area. The initial data from all sites show the standard characteristics of good quality: tidal signals with very high signal to noise ratio and large (～10,000 counts on 24 bit ADC system) amplitudes; strains trending into conpression with rates that decrease exponentially with time and earthquakes clearly recorded. Additionally the instruments have recorded a number of slow strain changes with durations ranging from about an hour up to a few days; we interpret these signals in terms of slow earthquakes. All of the slow events identified to date occur at the times of typhoons passing over or very close to the study area, but not all typhoons are associated with slow strain events (e.g. 9 typhoons in 2004 were accompanied by 5 slow events). Seismicity for the area deliniates a roughly north-south striking steeply dipping (to the west) zone with reverse slip; the shallowest extent of the zone is approximately 10 km inland. We look for source solutions consistent with that tectonic setting. The slow events exhibit a considerable range of amplitude and complexity; small, short amplitude events have a quite simple and smooth waveform; the longest (2 days) and largest (100 to 350 nanostrain at 3 sites) has waveforms with a lot of structure. The similarity among the stations (located in an isosceles triangular array with spacing ~ 10 km and 4 km) is indicative of rupture propagation of a slow slip source (equivalent magnitude about 5), propagating up dip and from south to north. Typhoon activity produces a large increase in short period (~ sec) energy so it is not possible to determine whether these slow events are accompanied by non-volcanic tremor, as has been reported for the Nankai subduction and Cascadia slow events. We hyothesize that the slow earthquakes are triggered by the typhoon activity due to lower air pressure over land reducing the normal force on the fault zone. 所以他们提出的理论是 台风的低压降低断层面的正向力(normal force) -> 引发slow earthquake （-> 断层能量得以释放，降低大地震发生的机会? 这点在摘要里没提到，也许口头发表时有说到，所以部落格里才会写出来） 重点是在slow earthquakes，这指的是断层面缓慢但持续时间较长的错动， （可持续数小时甚至数周，产生的震波很不明显， 除了特殊仪器strainmeter或GPS观测得到之外很难察觉） 跟一般所说的地震很不一样。 摘要里提到，台湾东部一年经由slow earthquake释放的能量， 约等同於五个规模五的地震， 也就是说，累积一到两百年的话，台风可能帮助释放一个规模七地震的能量。 --

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