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首页> 外文会议>Ninth International Conference on Ground Penetrating Radar GPR 2002, Apr 29-May 2, 2002, Santa Barbara, California USA >CHARACTERIZATION OF A TROPICAL ICE BODY ON IZTACCIHUATL VOLCANO, MEXICO
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CHARACTERIZATION OF A TROPICAL ICE BODY ON IZTACCIHUATL VOLCANO, MEXICO

机译：墨西哥伊兹塔奇华特火山上的热带冰体特征

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In the last century ice bodies have changed significantly worldwide in response to climatic changes, apparently enhanced during the last decades, presumably owing to anthropogenic influence. Shrinkage of glaciers in the northern latitudes has been extensively documented; however, the behavior of glaciers in tropical or inter-tropical latitudes has been difficult to document. In Mexico, small glaciers are present in the highest mountains: Citlaltepetl (5675 m), Popocatepetl (5452 m) and Iztaccihuatl (5286 m), all of them volcanoes. The glaciers of Mexico offer important clues about climate change at this latitude. Current inventory and monitoring of Mexican glaciers includes determination of glaciated areas and volumes. A survey has been carried out using ground-penetrating radar in order to get a figure of thickness and a preliminary volumetric estimate of an ice body of Iztaccfhuatl volcano named Ayoloco glacier. A radar profile 415 m in length was obtained at a mean altitude of 5000 m with an azimuth of 190° in a relatively flat area known as La Panza on top of the mountain. 100 Mhz antennas were used in the reflection mode with a separation of 2.5 m and a step-size of 2.5 m. A common mid-point survey was performed comprising 12 stations, at 0.5 m steps, to determine the wave velocity propagation in the ice-rock mixture that constitutes the glacier. Results yield a value of 0.17 ms, which is close to the reported value for ice of 0.16 ms. We find a layered structure perturbed by faulting at various inclinations, and an interface between the glacier and the underlying rock along a concave surface, shallow at the profile's extremes. There appears to be a transition at 50 m depth, from brittle to ductile ice. Since Iztaccihuatl volcano has many craters near the summit, we infer that this profile reveals the shape of one of the craters, which has been filled by the glacier's ice and a mixture of rock fragments and volcanic debris. The estimated upper volume of the Ayoloco glacier is 10.04 x 10~6 m~3; this figure will have to be revised when more, perpendicular GPR transects are performed.
机译：在上个世纪，冰体在全球范围内响应气候变化而发生了显着变化，在过去的几十年中，冰体明显增强了，这大概是由于人为因素造成的。大量记录了北纬冰川的萎缩；然而，在热带或热带纬度地区的冰川行为很难记录。在墨西哥，高山上有小冰川：西塔尔特佩特尔（5675 m），波波卡特佩特尔（5452 m）和伊兹塔奇瓦特（5286 m），它们都是火山。墨西哥冰川为这一纬度提供了有关气候变化的重要线索。墨西哥冰川的当前清单和监测包括确定冰川面积和体积。为了获得伊兹塔克富特特火山阿约洛科冰川的冰体厚度和初步体积估算，已经使用探地雷达进行了调查。在山顶上相对较平坦的区域称为La Panza，在5000 m的平均高度和190°的方位角上获得了415 m的雷达轮廓。 100 Mhz天线在反射模式下使用，间距为2.5 m，步长为2.5 m。进行了一个常见的中点测量，包括0.5 m步长的12个站点，以确定在构成冰川的冰岩混合物中的波速传播。结果得出的值为0.17 m / ns，与冰的报告值0.16 m / ns接近。我们发现层状结构在各种倾角下都受到断层的扰动，而冰川和下伏岩石之间沿着凹面的界面则在剖面的极限处变浅。从脆性冰到延性冰，在50 m深度似乎有一个过渡。由于Iztaccihuatl火山在山顶附近有许多火山口，我们可以推断出该剖面揭示了其中一个火山口的形状，该火山口已被冰川的冰以及岩石碎片和火山残渣的混合物填充。阿约洛科冰川的估计最高体积为10.04 x 10〜6 m〜3；当执行更多垂直的GPR样点时，必须修改此图。

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