Copahue volcano is an active stratovolcano located in the Southwest of the Agrio-Caviahue depression in the Province of Neuquén at the border between Argentina and Chile, and the most recent eruptive activity involved five cycles between 1992 and 2016. The Moderate Resolution Imaging Spectroradiometer (MODIS) is an instrument onboard the satellites Terra and Aqua that provides, on average, four images per day and has channels centered at 4 μm and 12 μm that are useful for detecting volcano temperature anomalies. In this work, we evaluated the normalized temperature index (NTI) as implemented by MODVOLC and the radiance recorded by MODIS at 4 μm as measures of precursory volcanic activity between October 2011 and January 2013, with a special focus on the December 2012 eruption. We evaluated the thermal anomalies identified by MODVOLC based on a global threshold of −0.8 and observed that they were namely syn- or post-eruptive and mostly correlated with the presence of incandescence material related to Strombolian activity. The global nighttime threshold was adapted to the local context of Copahue and we observed that a threshold of −0.875 is a more suitable value for the examined period. An analysis of time series of the NTI and of the radiance at 4 μm based on 116 MODIS images, resulted in that the adapted threshold allowed the detection of anomalies undetected by the global value. The anomalies were in either case unrelated to precursory activity but correlated with surface expressions of activity such as the emission of volcanic ash, volcano degassing, and the ejection of ballistic and incandescent material. The knowledge on the chronology of activity prior to and during the eruption could be improved, as regards the thermal behavior of the volcano in relation also to geochemical, deformation, and seismic signals. The replication of this kind of analysis in other periods of activity at Copahue and other volcanoes, the evaluation of other algorithms and the incorporation of data acquired by other satellite instruments are necessary to improve our knowledge on the temperature behavior of volcanoes before and during periods of unrest. This would ultimately contribute towards the improvement of volcano monitoring capabilities in volcanic areas.

科帕韦火山是活跃的平流火山，位于内乌肯省Agrio-Caviahue凹陷的西南部，位于阿根廷和智利之间的边界，最近的喷发活动涉及1992年至2016年之间的五个周期。中分辨率成像光谱仪（MODIS） ）是Terra和Aqua卫星上的仪器，平均每天提供四张图像，并具有以4μm和12μm为中心的通道，可用于检测火山温度异常。在这项工作中，我们评估了MODVOLC实施的归一化温度指数（NTI）和MODIS在4μm处记录的辐射度，作为2011年10月至2013年1月之间火山前兆活动的量度，特别着重于2012年12月的喷发。我们基于-0.8的整体阈值评估了由MODVOLC识别的热异常，并观察到它们是同生或爆发后的，并且与与Strombolian活动有关的白炽物质的存在最相关。全球夜间阈值已根据Copahue的当地情况进行了调整，我们观察到-0.875的阈值对于所检查的时间段更合适。基于116个MODIS图像对NTI和4μm处的辐射的时间序列进行分析，结果是，经过调整的阈值允许检测到未被全局值检测到的异常。在任一情况下，异常都与前驱活动无关，但与活动的表面表达相关，例如火山灰的散发，火山的脱气以及弹道和白炽物质的喷出。关于火山的热行为，以及与地球化学，变形和地震信号相关的火山热行为，有关火山喷发之前和期间的活动时间的知识可以得到改善。在Copahue和其他火山的其他活动时期重复进行这种分析，评估其他算法以及整合其他卫星仪器获得的数据，对于提高我们对火山爆发之前和期间的温度行为的认识是必不可少的。动荡。这最终将有助于提高火山地区的火山监测能力。在Copahue和其他火山的其他活动时期重复进行这种分析，评估其他算法以及整合其他卫星仪器获得的数据，对于提高我们对火山爆发之前和期间的温度行为的认识是必不可少的。动荡。这最终将有助于提高火山地区的火山监测能力。在Copahue和其他火山的其他活动时期重复进行这种分析，评估其他算法以及整合其他卫星仪器获得的数据，对于提高我们对火山爆发之前和期间的温度行为的认识是必不可少的。动荡。这最终将有助于提高火山地区的火山监测能力。