在引發地震的過程中雨水或許扮演了重要腳色

原文網址：www.sciencedaily.com/releases/2016/04/160427094859.htm

Rainwater may play an important role in process that triggers earthquakes

在引發地震的過程中雨水或許扮演了重要腳色

It's the rain's Fault

都是雨水惹的禍(斷層，兩者英文皆為fault)

Rainwater may play an important role in the process that triggers earthquakes, according to new research.

根據新的研究顯示，在引發地震的過程中雨水或許扮演了重要腳色。

Researchers from the University of Southampton, GNS Science (New Zealand), the University of Otago, and (Germany), identified the sources and fluxes of the geothermal fluids and mineral veins from the Southern Alps of New Zealand where the Pacific and Australian Plates collide along the Alpine Fault.

來自南安普敦大學、紐西蘭地質與核子科學研究所、奧塔哥大學以及德國波茨坦地質科學研究中心的研究人員，發現了紐西蘭南阿爾卑斯山脈的地熱流體和礦脈的來源與流量。紐西蘭的阿爾卑斯斷層為太平洋板塊跟印澳板塊聚合碰撞之處。

From careful chemical analyses, they discovered that fluids originating from the mantle, the layer below Earth's crust, and fluids derived from rainwater, are channelled up the Alpine Fault.

經過審慎的化學分析之後，他們發現源自地殼下方的地函流體以及從降雨而來的液體，會在阿爾卑斯斷層中彼此連通。

By calculating how much fluid is flowing through the fault zone at depth, the researchers showed for the first time that enough rainwater is present to promote earthquake rupture on this major plate boundary fault.

經由計算會有多少的液體流經斷層帶深部後，研究人員首次呈現出在這條大型板塊邊界斷層帶中，具有相當含量的雨水能夠促使斷層破裂並產生地震。

Lead researcher Dr Catriona Menzies, from Ocean and Earth Science at the University of Southampton, said: "Large, continental-scale faults can cause catastrophic earthquakes, but the trigger mechanisms for major seismic events are not well known. Geologists have long suspected that deep groundwaters may be important for the initiation of earthquakes as these fluids can weaken the fault zones by increasing pressures or through chemical reactions.

此篇研究的第一作者，南安普敦大學的海洋和地球科學博士Catriona Menzies說：「大型斷層帶可能會引起毀滅性的地震，但我們對於大型地震的觸發機制仍未具有全面性的了解。地質學家長久以來便猜測深層地下水對地震的引發而言相當重要。這是因為液體會增強水壓或是產生化學反應而弱化斷層帶。」

"Fluids are important in controlling the evolution of faults between earthquake ruptures. Chemical reactions may alter the strength and permeability of rocks, and if enough fluid is present at sufficiently high pressures they may aid earthquake rupture by 'pumping up' the fault zone."

「斷層在一次次破裂而引發地震的演化過程中，液體具有相當重要的控制地位。化學反應或許會改變岩石的強度以及滲透性，另外，若有相當多的液體在斷層帶中而產生夠高的水壓，這些液體或許能將其『抬起』而助長地震破裂發生。」

The Alpine Fault is a major strike-slip fault, like the San Andreas, that fails in very large (Magnitude 8+) earthquakes around every 300 years. It last ruptured in 1717 AD and consequently it is under intense scientific scrutiny because it is a rare example of a major fault that is late in the strain-build up before rupture.

阿爾卑斯斷層跟聖安地列斯斷層一樣是條大型平移斷層。它大約每300年就會發生一次相當大型(規模8以上)的地震，而上一次破裂發生在西元1717年。因為如此，它成為可能正在破裂邊緣，應力正不斷累積的罕有大型斷層例子，使得現在有許多科學監測活動正在進行。

Dr Menzies said: "We show that the Alpine Fault acts as a barrier to lateral fluid flow from the high mountains of the Southern Alps towards the Tasman Sea in the west. However, the presence of mantle-derived fluids indicates that the fault also acts as a channel for fluids, from more than 35 km depth, to ascend to the surface.

Menzies博士說：「我們的結果顯示出地下水在從南阿爾卑斯的高山地區往西方的塔斯曼海側向流動時，阿爾卑斯斷層具有阻斷的作用。然而，斷層中具有源自地函的流體的這件事指出，它同時也可以作為液體流通的管道。來自深度超過地下35km處的液體，能夠經此而上升至地表。」

"As well as mantle derived fluids, our calculations indicate that 0.02-0.05 per cent of surface rainfall reaches around six kilometres depth but this is enough to overwhelm contributions from the mantle and fluids generated during mountain-building by metamorphic reactions in hot rocks. This rainwater is then focused onto the fault, forced by the hydraulic head of the high mountains above and the sub-vertical fluid flow barrier of the Alpine Fault."

「除了來自地函的液體之外，我們的計算指出地表的降雨有百分之0.02至0.05可以到達地下6公里深。即使如此，這些量已遠遠超過地函來的液體，以及在造山運動時熾熱岩石經由變質作用而產生的液體。在上方高山造成的水頭，以及近乎垂直的阿爾卑斯斷層作為液體流動的屏障作用下，這些雨水會集中於斷層上。」

Funding for this research, published in Earth and Planetary Science Letters, was provided by the Natural Environmental Research Council (NERC), Deutsche Forschungsgemeinschaft, and GNS Science (New Zealand).

此篇刊登於期刊《地球和行星科學通訊》的研究，資金來自於自然環境研究委員會、德國研究學會和 紐西蘭地質與核子科學研究所。

引用自：University of Southampton. "Rainwater may play an important role in process that triggers earthquakes." ScienceDaily. ScienceDaily, 27 April 2016.