Anticipating the ice avalanche with radar data

作者：洛伦兹·迈耶（Lorenz Meier）

自然危害和相关损害的风险在全球范围内上升。广泛的保护结构是昂贵的，可能不会自行损害。空间规划和预防措施已成为成功的民事和资产保护的最重要行动。对特定危害过程的永久监控允许早日检测到迫在眉睫的风险或危险情况的持续修改。如果设置并正确使用，则可以通过警告和警报系统大大减少事件造成的潜在损害。

The Swiss-based technology company Geopraevent is an expert in this field. Geopraevent develops, installs and operates customised alarm and monitoring systems for various natural hazards, such as avalanches (snow and ice), rock fall, debris flows or floods. The applied technologies include different types of radar, e.g. the interferometric radar supplied by Italy-based leading provider of Ground Penetrating Radar and interferometric technology solutions IDS GeoRadar. Geopraevent currently runs more than 60 systems globally, many of them in high mountain environments. Recently, one of them clearly demonstrated the ability to预测即将发生的事件并提早反应：Trift冰川在位于瑞士瓦利斯地区SaaS Grund村庄上方的Weissmies上的失败。

Challenging monitoring task in an alpine environment

Fletschhorn（3993米），Lagginhorn（4010 M）和Weissmies（4017 m）的著名峰会将SaaS-Valley与瑞士南部的Simplon Valley分开。从位于瓦利斯广州霍萨斯的缆车站很容易到达，魏斯米斯是该地区最常见的攀登峰之一。

In summer 2014, the Trift Glacier, located on the north-west face of Weissmies, showed increased ice avalanche activity. The hanging glacier, formerly supported by ice from below, had destabilised due to glacier mass loss predominating in steeper areas. Canton of Wallis authorities approached Geopraevent with the request to monitor the glacier movement to enable early actions in case of possible ice failures resulting in a large ice/snow avalanche. The specialised engineers of Geopraevent visited the measurement site immediately and supplied the local decision makers and responsible authorities withglacier velocity dataon the evening of the day of installation.

Interferometric radar data integrated into geotechnical analysis provides the detailed information required to the experts judging the situation. Interferometric radar is a reliable technique for short or long-term monitoring of multiple scales of displacements regardless of visibility and weather conditions. The radar measures spatially resolved deformation rates with high accuracy.IDS GeoRadar IBIS FM radaris the system deliveringreliable and accurate data of displacements in real time despite the atmospheric correction needed in high altitudes。In addition, a high-definition camera was installed at this location and proved to be an excellent alternative for automatic long-term deformation analysis if weather is not an issue.

关键的滑坡和冰雪崩监测

尽管冰川上的湍流气氛有时会妨碍测量值，但每天都可以获得可靠的测量。为了说明高度可变的高山条件，Geopraevent添加了一个额外的处理步骤，该步骤在通过其通过其提供给客户之前验证数据的合理性online data portal。This provided sufficient data for VAW/ETH Professor’s Martin Funk group and the local geoformer GmbH’s engineers tointerpret the prevailing hazardfor the area below the hanging glacier.

“经过将近三年的连续雷达监测，统计数据表明，雷达在95％的天数上提供了可行的变形数据。雷达测量仅在大暴风雪中暂时失败，这是由于雪和雨引起的表面变化，”said Richard Steinacher, physicist and project leader at Geopraevent.

Compared to the rest of the glacier moving at about 10 centimetres per day, the unstable part initially moved at a significantly higher velocity of approximately 25 cm per day. Between 2014 and 2017, dozens of small and harmless ice avalanches could be predicted from the radar data usually a few days in advance.

通过预测不可避免的来挽救生命

经过2。5年的成功操作后，2017年初的高分辨率摄像头取代了干涉范围，以进行视觉变形分析。该摄像机提供了出色的结果，该摄像机在允许的情况下跟踪了冰川每天的运动。摄像机分析揭示了从8月20日左右开始的冰川的明显加速^th。在9月初，很明显，冰川很快就会失败。

To provide velocity data also during night and bad weather, Geopraevent re-installed the interferometric radar on September 7^th。Velocities were on the order of 80 cm per day and accelerated to more than 2 m per day on Saturday, September 9^th。那天的崩溃预测表明，冰量高达4000万m³would fail in the early morning of Sunday, September 10^th。Consequently, 220 inhabitants of theSaaS Grund的濒危村庄部分被撤离。Most of the unstableice volume collapsed, as predicted，在周日上午6点左右。幸运的是，冰的雷达干涉图揭示了十分钟之内的几小部分。没有造成损害，到上午8点。所有居民都可以返回家园。

实时安全监控和长期计划

IDS GeoRadar IBIS-FM system collects quantitative information on slope behaviour from either a spatial or a temporal point of view. It provides reliable early-detection alerts on impending failures in real time, as well as accurate geo-referenced outputs over long periods of time allowing users tointegrate radar data into geotechnical analysis of slope failure mechanisms。

“IBIS-FM雷达准确监控多个scales of displacements in real time, from early detection of slow movements to fast accelerations associated with slope collapse. The great operative range, up to 4500 metres allows to safely deploy the system in comfortably accessible areas without exposing people and equipment to hazardous zones,”IDS Georadar Geo业务部门经理Paolo Papeschi说。“Thanks to the most advanced automatic algorithms in the market, IBIS-FM delivers reliable and accurate data in all weather conditions. Monitoring experts can respond to slope hazards faster ensuring the safety of operators and the public.”

Geopraevent also installed an IDS GeoRadar system above Bondo in the region of Bergell, in Canton of Graubunden, Switzerland, after a massive landslide occurred in August 2017. The radar, installed on 3 September 2017, monitors the Pizzo Cengalo permanently anddetects millimeter-movements in all weather conditions。The radar allows to predict new rockfalls early and initiate appropriate measures; a rock fall event on 15 September 2017 was predicted about one day in advance.