Muography of 1949 fault in La Palma, Canary Islands, Spain
Muography of 1949 fault in La Palma, Canary Islands, Spain
复制标题
DOI：
10.4401/ag-7385
复制
发表时间：
2017-01-01
影响因子：
1
通讯作者：
Tioukov, Valeri
中科院分区：
文献类型：
--
作者：
Miyamoto, Seigo;Barrancos, Jose;Tioukov, Valeri
μ子照相术是一种新的地球物理技术，它可以以非常详细的空间分辨率调查建筑物的内部结构。它最近被用于几个火山和不同的地球科学目标。2011年，田中等人成功地发现了隐藏的古代地震断层。1949年，西班牙加那利群岛拉帕尔马的Cumbre Vieja火山活动，在活动期间突然出现了一条1公里长的断层。断层可能是大规模陆地塌陷的标志。为了获得更多的信息，需要通过多种地球物理勘探技术进行调查。我们认为，磁层析成像技术可用于断层浅部的研究，它可以明确一些重要的参数：体积密度、低密度带的宽度和深度。以前的调查允许检测两个古老的地震断层，具有20米宽的机械断裂带，由高度受损的岩石组成。1949年断层可能是大规模滑坡的结果，滑坡长度可能只有几米。因此，断层的预期宽度只有几米。为了探测这种窄断层，μ子探测器应具有尽可能高的空间分辨率。此外，在故障附近很难获得连续的电力供应。核乳胶是一种对高能带电粒子具有高感光度的照相胶片。它们还具有高能量μ子路径的高空间分辨率，并且不需要任何电源来操作。我们在1949断层附近放置了一个有效面积为0.19 m2的乳胶探测器。暴露于2014年1月开始，持续106天。所有的乳胶胶片都已显影，正在分析中。我们还估计了该测试暴露的预期性能。假设一个非常简单的模型，我们评估了可探测区域作为低密度区宽度和距离地面的深度的函数。
Muography (muon radiography) is a new geophysical technique that allows investigation of inner structures of an edifice with a very detailed spatial resolution. It has been recently used for several volcanoes and different geoscientific targets. In 2011 Tanaka et al. succeeded to find hidden ancient seismic faults. In 1949 there was a volcanic activity of the Cumbre Vieja, La Palma, Canary Islands, Spain and a 1km-long fault suddenly appeared during the active period. The fault might be the sign of a large scale land collapse. In order to get additional information, investigations by several geophysical exploration techniques are needed. We consider that muography can be applied to study the shallow part of the fault and it can clarify some important parameters: the bulk density, the width of the low density zone, and the depth. Previous investigations allowed detecting two ancient seismic faults that have 20m-wide mechanically fractured zone consisting of highly damaged rocks. The 1949 fault might be the result of large scale land slide and the slide length might be just a few meter. Therefore the expected width of the fault is only a few meter. In order to detect such narrow fault, the muon detector should have as high spatial resolution as possible. In addition, it is difficult to get continuous power supply near the fault. Nuclear emulsions are a kind of photographic films that have high sensitivity for high energy charged particles. They also have high spatial resolution for high energy muon paths and do not need any power supply to be operated. We placed an emulsion detector having 0.19 m(2) effective area near the 1949 fault. The exposure started on January 2014 and lasted 106 days. All the emulsion films were developed and they are under analysis. We also estimated the expected performance of this test exposure. Assuming a very simple model, we evaluated the detectable region as a function of the low density zone width and of the depth from the ground surface as well.