利用地面原子鐘監測火山

原文網址：www.sciencedaily.com/releases/2015/06/150630080156.html

Monitoring volcanoes with ground-based atomic clocks

利用地面原子鐘監測火山

An international team led by scientists from the University of Zurich finds that high-precision atomic clocks can be used to monitor volcanoes and potentially improve predictions of future eruptions. In addition, a ground-based network of atomic clocks could monitor the reaction of Earth's crust to solid Earth tides.

由蘇黎世大學(the University of Zurich)的科學家所率領的國際團隊發現高精度的原子鐘(atomic clock)可以用來監測火山，並有潛力對未來的爆發做出更精準的預測。此外，原子鐘的地面觀測網還能夠監測地殼對固體地潮的反應。

Atomic clocks measure time with unbelievable accuracy. The best atomic clocks are so precise that they would lose less than one second over a period of 10 billion years. However, they are generally only used in laboratories. Science and industry have yet to take full advantage of their unprecedented ability to measure time. An international team including Dr. Ruxandra Bondarescu, Andreas Schärer and Prof. Philippe Jetzer from the Institute of Physics from the University of Zurich discusses potential applications for atomic clocks.
原子鐘能夠以不可思議的準確度測量時間。最好的原子鐘可以精準至100億年內誤差不到一秒。然而，一般只有在實驗室內才會用到它們。科學界與產業界尚未能夠完全發揮它們前所未見的高精準計時能力。包括蘇黎世大學物理研究所的Ruxandra Bondarescu與Andreas Schärer博士及Philippe Jetzer教授的國際研究團隊對原子鐘的潛在應用面提出討論。
Their analysis shows that the slow down of time predicted by general relativity can be measured by local clocks and used to monitor volcanoes. General relativity states that clocks positioned at different distances from a massive body like Earth have different tick rates. The closer a clock is to a massive object, the slower it ticks. In a similar manner, subterranean objects influence the tick rate of local clocks that are located above Earth's surface. New lava filling a magma chamber beneath a volcano makes a clock located above that volcano tick more slowly than a clock that is located further away. Volcanoes are currently monitored using GPS receivers. The resulting data often has to be integrated over a period of several years before an estimate of the volume of new magma can be made. A network of local, highly precise atomic clocks may provide the same information within a few hours. This would make it possible to monitor processes inside volcanoes more closely and to make better predictions for future volcanic eruptions.
他們的分析顯示地面原子鐘可以測量到廣義相對論所預測的時間減速，並能夠用來監測火山活動。在廣義相對論的敘述中，當兩座時鐘跟地球這種大質量物體的距離不一樣時，它們的行走速率也會不一樣。時鐘離大質量物體越近，行走速率就會越慢。類似地，在地下的物體也會影響位於上方地表的時鐘的行走速率。當新的熔岩進入火山下方的岩漿庫時，它會造成位於火山上方的時鐘的運行速率變得比遠方的時鐘還要慢。現今我們利用GPS接收器來監測火山，這通常需要先累積數年的觀測資料才能開始預估新的岩漿體積有多少。然而，架設在當地，精準度極高的地面原子鐘觀測網卻可能可以在數個小時內提供給我們相同的資訊。這讓我們可以更詳細的觀測火山內部的活動，並且對未來的火山噴發做出更精準的預測。
Monitoring the solid Earth tides with a global network of atomic clocks
利用全球原子鐘觀測網來監測固體地潮
Atomic clocks can also be used to monitor the solid Earth tides. Tides occur because Earth moves in the gravitational field of the Sun and the Moon. It reacts to this outer field by deforming, which in turn leads to ocean tides and to the ground on the continents lifting and falling regularly. The ground can rise as much as 50 cm. A global network of atomic clocks that are connected via fiber optic cables used for internet, could provide continuous measurements of Earth tides and check existing theoretical models. It would also be possible to examine any local differences in the response of Earth's crust to Earth tides.
原子鐘也能夠用來監測固體地潮(solid Earth tide)。潮汐的發生原因是因為地球在太陽與月球的重力場之間運行。這些外在的重力場會讓地球變形，造成海洋發生潮汐，而地面也會規律的漲落，幅度可達到50 cm。利用串聯網路的光纖來建立全球原子鐘觀測網，可以持續地測量地潮並用來驗證現行的理論模型是否符合觀測結果，並且能夠用來觀察地殼對地潮的反應是否有區域性差異存在。
The researchers hope that high precision clocks could be deployed in volcanic areas in the next few years. This is, however, subject to sufficient interest and investment from industry. "We need this additional tool to monitor magma movement under volcanoes such as the Yellowstone supervolcano, which is overdue for an explosion that would alter life on Earth as we known it," explains Bondarescu.
研究人員冀望在未來的幾年內這種高精確度的時鐘便能夠實際運用在火山地區。然而，這有賴於產業界是否有充分的興趣而決定投資。「我們需要額外的工具來監測像是黃石公園這類超級火山之下的岩漿活動，據我們所知它們的噴發足以改變地球上的全體生物，且這早就應該要發生了。」Bondarescu解釋。

引用自University of Zurich. "Monitoring volcanoes with ground-based atomic clocks." ScienceDaily. ScienceDaily, 30 June 2015.