Capturing a new episode of unrest at Santorini volcano, Greece

圣托里尼火山是爱琴海（希腊）的一座主要火山，它最出名的是发生在大约3600年前的一次大喷发（米诺斯火山喷发），并对整个地中海东部的环境和政治产生了重大影响。那次喷发形成了一个大火山口，现在被海水淹没，自那以后，圣托里尼岛的火山活动被限制在火山口中间的一小块区域。在过去的500年里，发生了6次中等规模的喷发，形成了年轻的尼亚岛和帕利亚卡梅尼岛。这些火山爆发通常没有什么预警——几次非常小的地震；岛屿的一些运动（上下），以及该地区许多温泉周围海水的一些变化。每一次喷发都伴随着缓慢的岩浆挤压，还有几次更剧烈的爆炸，以及熔岩块、火山灰和有毒气体的喷射。最后一次，也是最小的一次喷发发生在1950年。自1950年以来，圣托里尼岛一直处于平静状态——很少发生地震，也很少排放气体。最近，在野外工作中，我们在最年轻的火山口附近测量到气体排放率的大幅增加。我们现在还看到圣托里尼岛主岛（用全球定位系统测量）和新卡梅尼岛（用卫星测量）的一些快速移动：这表明这些岛屿正在以每月几厘米的速度上升。这里还发生了一系列非常小的地震，其中一些地震大到岛上居民都能感觉到。我们认为，所有这些证据表明，圣托里尼岛已经开始了一个重要的“动荡”阶段。我们所看到的动荡模式与一些历史喷发前报道的信号相似，我们建议进行密集的野外活动，测量与这个主要破火山口火山膨胀有关的地面变形和气体排放。因为科学家很少有机会在动荡时期监测火山口火山的行为，我们真的还不知道如何区分背景活动和喷发前可能发生的活动，至少在喷发发生前很短的时间内。由于这个原因，我们希望利用这个难得的机会来测量一个静止但危险的火山的浅扰动的变化。

Santorini is a major volcano in the Aegean sea (Greece), which is best known for a major eruption (the Minoan eruption) that occurred about 3,600 years ago, and has been implicated in major environmental and political impacts across the eastern Mediterranean. Since that eruption, which formed a large caldera, now flooded by the sea, volcanic activity at Santorini has been restricted to a small region in the middle of the caldera. Over the past 500 years, six moderate eruptions have taken place, forming the young islands of Nea and Palea Kameni. These eruptions have usually happened with little warning - a few very small earthquakes; some movements of the islands (up and down), and some changes in the seawater around the many hotsprings in the area. Each of these eruptions has involved the slow squeezing out of lava, with a few more dramatic explosions and the ejection of blocks of lava, ash and noxious gases. The last, and smallest, of these eruptions took place in 1950. Since 1950, Santorini has been quiescent - with very few earthqaukes, and very little gas emission. Recently, during fieldwork, we measured a large increase in gas emission rates from near the youngest volcanic vent. We have also now seen some rapid movements of the main island of Santorini (measured by GPS), and of New Kameni (measure by satellite): these show that the islands are being lifted up by a few centimetres per month. There has also been a major swarm of very small earthquakes, some of which have been large enough to be felt by the residents of the islands. We think that all of this evidence shows that Santorini has begun a significant phase of 'unrest'. The pattern of unrest that we have seen is similar to the signals reported that happen before some of the historical eruptions, amd we propose an intensive field campaign to measure the ground deformation and gas emissions, associated with the inflation of this major caldera volcano. Because there have been very few opportunities for scientists to monitor the behaviour of caldera volcanoes during periods of unrest, we really don't yet know how to distinguish between background activity, and activity which might happen before an eruption, at least until just a very short time before an eruption happens. For this reason, we wish to use this rare opportunity to measure the changes with a shallow disturbance at a quiescent but dangerous volcano.