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首页> 外文期刊>Nature >Widespread uplift and 'trapdoor' faulting on Galapagos volcanoes observed with radar interferometry
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Widespread uplift and 'trapdoor' faulting on Galapagos volcanoes observed with radar interferometry

机译：用雷达干涉仪观测到的加拉帕戈斯火山大范围隆升和“陷门”断裂

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摘要

Volcanic uplift, caused by the accumulation of magma in subsurface reservoirs, is a common precursor to eruptions. But, for some volcanoes, uplift of metres or more has not yet led to an eruption. Here we present displacement maps of volcanoes in the Galapagos Islands, constructed using satellite radar interferometry, that might help explain this dichotomy. We show that all but one of the seven volcanoes on the islands of Isabela and Fernandina deformed during 1992-99. Cerro Azul and Fernandina erupted during the observation period and show evidence of inflation, co-eruptive deflation and shallow dyke intrusion. In contrast, the largest volcano, Sierra Negra, has not erupted, yet exhibits spatially and temporally variable deformation, with a maximum uplift of 2.7 m between 1992 and 1999, which can be modelled by a shallow inflating sill. Inflation during 1997-98, however, was accompanied by 'trapdoor' faulting on a steeply dipping fracture system within the caldera. Repeated trapdoor faulting over geological time has formed an arcuate intra-caldera ridge within Sierra Negra and may have acted to relax stresses above the magma chamber, inhibiting summit eruptions. Similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes.
机译：岩浆在地下储层中的堆积引起的火山隆升是喷发的常见先兆。但是，对于某些火山而言，米数或更高的上升尚未引起喷发。在这里，我们介绍了加拉帕戈斯群岛上火山的位移图，这些图是使用卫星雷达干涉仪绘制的，这可能有助于解释这种二分法。我们表明，伊莎贝拉岛和费尔南迪纳岛上的七个火山中，除了七个火山之一，在1992-99年期间发生了变形。塞罗·阿祖尔（Cerro Azul）和费南迪纳（Fernandina）在观测期间爆发，并显示出通货膨胀，协同喷出的通缩和浅堤侵入的迹象。相比之下，最大的火山Sierra Negra尚未爆发，但表现出随时间和空间变化的变形，在1992年至1999年之间最大隆起为2.7 m，这可以用一个浅的膨胀槛来模拟。然而，1997-98年期间的通货膨胀伴随着破火山口内陡倾裂缝系统的“活板门”断裂。在地质时期内反复出现的圈闭断层在塞拉内格拉内形成了一个弧形的火山口内脊，可能起到了缓解岩浆腔上方应力的作用，从而抑制了山顶喷发。类似的过程可能有助于解释没有其他火山爆发活动伴随的大隆升。

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