A growing body of research indicates that rock slope failures, particularly from exfoliating cliffs, are promoted by rock deformations induced by daily temperature cycles. Although previous research has described how these deformations occur, full three-dimensional monitoring of both the deformations and the associated temperature changes has not yet been performed. Here we use integrated terrestrial laser scanning (TLS) and infrared thermography (IRT) techniques to monitor daily deformations of two granitic exfoliating cliffs in Yosemite National Park (CA, USA). At one cliff, we employed TLS and IRT in conjunction with in situ instrumentation to confirm previously documented behavior of an exfoliated rock sheet, which experiences daily closing and opening of the exfoliation fracture during rock cooling and heating, respectively, with a few hours delay from the minimum and maximum temperatures. The most deformed portion of the sheet coincides with the area where both the fracture aperture and the temperature variations are greatest. With the general deformation and temperature relations established, we then employed IRT at a second cliff, where we remotely detected and identified 11 exfoliation sheets that displayed those general thermal relations. TLS measurements then subsequently confirmed the deformation patterns of these sheets showing that sheets with larger apertures are more likely to display larger thermal-related deformations. Our high-frequency monitoring shows how coupled TLS and IRT allows for remote detection of thermally induced deformations and, importantly, how IRT could potentially be used on its own to identify partially detached exfoliation sheets capable of large-scale deformation. These results offer a new and efficient approach for investigating potential rockfall sources on exfoliating cliffs.

中文翻译：

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剥离片变形的远程热检测

越来越多的研究表明，每日温度循环引起的岩石变形会促进岩石边坡的破坏，尤其是剥落的悬崖。尽管之前的研究已经描述了这些变形是如何发生的，但尚未对变形和相关的温度变化进行全面的三维监测。在这里，我们使用集成的地面激光扫描 (TLS) 和红外热成像 (IRT) 技术来监测优胜美地国家公园（美国加利福尼亚州）的两个花岗岩剥落悬崖的日常变形。在一个悬崖上，我们使用 TLS 和 IRT 结合原位仪器来确认先前记录的剥落岩板的行为，在岩石冷却和加热期间，剥落裂缝每天都会闭合和打开，从最低和最高温度延迟几个小时。板材变形最大的部分与断裂孔径和温度变化最大的区域重合。建立一般变形和温度关系后，我们在第二个悬崖上使用 IRT，在那里我们远程检测并识别了 11 个显示这些一般热关系的剥落片。TLS 测量随后证实了这些板材的变形模式，表明具有较大孔径的板材更有可能显示出更大的与热相关的变形。我们的高频监测显示了耦合 TLS 和 IRT 如何允许远程检测热致变形，重要的是，如何单独使用 IRT 来识别能够进行大规模变形的部分分离的剥离片。这些结果为调查剥落悬崖上的潜在落石源提供了一种新的有效方法。