Shear-wave splitting Tomography At Kilauea

夏威夷的基拉韦厄火山是世界上最活跃的火山之一。自2008年以来，在火山的顶部有一个喷发口，有一个熔岩湖。在火山的更深处，自1985年以来还有另一个喷口在喷发熔岩。2018年4月，岩浆供应在这两个地方停止，并在地下流向普纳的居民区，在那里它在24个不同的裂缝中喷发。超过2000人从家中撤离，多达700座建筑被熔岩流摧毁。这个地区上一次火山喷发是在1960年。当岩浆穿过岩石时，会引起许多小地震。地震波的极化方式与光的极化方式类似。岩石在压力下会使地震波极化，微小的裂缝会沿一个方向排列。这导致地震波在一个方向（沿着裂缝）比另一个方向（穿过裂缝）传播得快。因此，我们可以利用地震波的偏振来了解岩浆穿过岩石时岩石是如何受压的。基拉韦厄火山的新喷发活动意味着我们可以调查以前因为地震不够而无法调查的地区。我们将建立四个新的台站来测量新的地震，并使用现有监测网的数据。我们将使用新的地震来拍摄火山喷发期间岩石压力的图像，并能够看到火山喷发停止时压力发生了什么变化。这些信息将有助于了解基拉韦厄火山的喷发行为，有助于监测和预测喷发活动的变化，也将应用于世界各地的其他火山系统。为此，我们组建了一支来自东安格利亚大学和美国地质调查局的优秀研究人员团队。

Kilauea volcano, in Hawaii, is one of the most active volcanoes in the world. Since 2008, there has been an eruptive vent at the summit of the volcano, with a lava lake. Further down the volcano, there has been another vent erupting lava since 1985. In April 2018, magma supply stopped at these two places, and travelled under the ground to the residential region of Puna, where it erupted in 24 different fissures. Over 2000 people have been evacuated from their homes and up to 700 buildings have been destroyed by lava flows. The last time there was an eruption in this area was 1960.When magma pushes its way through the rock, it causes lots of small earthquakes. Earthquake waves can be polarised in a similar way to the way light is polarised. Rock polarises earthquake waves when it is under pressure and tiny cracks line up in one direction. This causes earthquake waves to travel faster in one direction (along the cracks) than the other (across the cracks). Therefore, we can use the polarisation of the earthquake waves to understand how the rock gets pressurised as the magma travels through it.This new eruptive activity at Kilauea means that we can investigate areas that we previously couldn't because there were not enough earthquakes. We will set up four new stations to measure the new earthquakes and use data from the existing monitoring network. We will use the new earthquakes to make images of the pressure in the rocks during this eruption and will be able to see what happens to the pressure when the eruption stops. This information will be useful to understand the eruptive behaviour of Kilauea, will help monitoring and forecasting changes in eruptive activity, and will also be applied to other volcanic systems around the world. To do this, we have made a team of excellent researchers from the University of East Anglia and the US Geological Survey.