Department of Geology, University of Patras, 265 04 Patras, Greece.
Sensors (Basel). 2022 Nov 13;22(22):8768. doi: 10.3390/s22228768.
Volcanic eruptions pose a great threat to humans. In this context, volcanic hazard and risk assessment constitute crucial issues with respect to mitigating the effects of volcanic activity and ensuring the health and safety of inhabitants. Lava flows directly affect communities living near active volcanoes. Nowadays, remote sensing advances make it possible to effectively monitor eruptive activity, providing immediate and accurate information concerning lava evolution. The current research focuses on the mapping of the surface deformation and the analysis of lava flow evolution occurred on the island of La Palma, during the recent (2021) eruptive phase of the volcano. Sentinel-1 data covering the island were collected throughout the entire eruptive period, i.e., September 2021 until January 2022. The processing was based on amplitude-based and phase-based detection methods, i.e., Synthetic Aperture Radar interferometry (InSAR) and offset tracking. In particular, ground deformation occurred on the island, while Line-Of-Sight (LOS) displacements were derived from Sentinel-1 interferograms. Moreover, the evolution of lava flow velocity was estimated using Sentinel-1 imagery along with offset tracking technique. The maximum lava flow velocity was calculated to be 2 m/day. It was proved that both approaches can provide rapid and useful information in emergencies, especially in inaccessible areas. Although offset tracking seems a quite promising technique for the mapping of lava flows, it still requires improvement.
火山爆发对人类构成了巨大威胁。在这种情况下，火山灾害和风险评估是减轻火山活动影响和确保居民健康与安全的关键问题。熔岩流直接影响到居住在活火山附近的社区。如今，遥感技术的进步使得对喷发活动进行有效监测成为可能，从而提供有关熔岩演化的即时、准确信息。目前的研究重点是对拉帕尔马岛在最近（2021 年）火山喷发期间发生的地表变形和熔岩流演化进行测绘。在整个喷发期间，即 2021 年 9 月至 2022 年 1 月，收集了覆盖该岛的 Sentinel-1 数据。处理过程基于基于幅度和基于相位的检测方法，即合成孔径雷达干涉测量（InSAR）和偏移跟踪。特别是，在岛上发生了地面变形，而视线（LOS）位移则来自 Sentinel-1 干涉图。此外，还使用 Sentinel-1 图像和偏移跟踪技术估算了熔岩流速的演化。计算得出的最大熔岩流速为 2 m/天。事实证明，这两种方法都可以在紧急情况下提供快速有用的信息，尤其是在难以到达的地区。尽管偏移跟踪似乎是一种用于熔岩流测绘的很有前途的技术，但它仍需要改进。
