Cabrera-Pérez Iván, Soubestre Jean, D'Auria Luca, Barrancos José, Martín-Lorenzo Alba, van Dorth David Martínez, Padilla Germán D, Przeor Monika, Pérez Nemesio M
Instituto Volcanológico de Canarias (INVOLCAN), 38600, Granadilla de Abona, Tenerife, Canary Islands, Spain.
Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre, 38000, Grenoble, France.
Sci Rep. 2023 Aug 9;13(1):12892. doi: 10.1038/s41598-023-39910-z.
La Palma island is located in the NW of the Canary Islands and is one of the most volcanically active of the archipelago, therefore the existence of geothermal resources on the island is highly probable. The main objective of this work is to detect velocity anomalies potentially related to active geothermal reservoirs on La Palma island, by achieving a high-resolution seismic velocity model of the first few kilometres of the crust using Ambient Noise Tomography (ANT). The obtained ANT model is merged with a recent local earthquake tomography model. Our findings reveal two high-velocity zones in the island's northern and southern parts, that could be related to a plutonic intrusion and old oceanic crust materials. Conversely, four low-velocity zones are imaged in the southern part of the island. Two of them can be related to hydrothermal alteration zones located beneath the Cumbre Vieja volcanic complex. This hypothesis is reinforced by comparing the S-wave velocity model with the seismicity recorded during the pre-eruptive phase of the 2021 Tajogaite eruption, which revealed an aseismic volume coinciding with these low-velocity zones. Another low-velocity zone is observed in the southern part of the island, which we interpret as highly fractured rocks which could favour the ascent of hot fluids. A last low-velocity zone is observed in the central part of the island and associated with loose deposits generated by the Aridane valley mega landslide.
拉帕尔马岛位于加那利群岛的西北部，是该群岛中火山活动最为活跃的岛屿之一，因此该岛存在地热资源的可能性很大。这项工作的主要目标是通过利用环境噪声层析成像（ANT）获得地壳最初几公里的高分辨率地震速度模型，来探测与拉帕尔马岛活跃地热储层潜在相关的速度异常。将获得 的ANT模型与最近的局部地震层析成像模型合并。我们的研究结果揭示了该岛北部和南部的两个高速区，这可能与深成侵入体和古老的大洋地壳物质有关。相反，在该岛南部成像了四个低速区。其中两个可能与位于坎布雷维耶哈火山复合体下方的热液蚀变带有关。通过将S波速度模型与2021年塔约加伊特火山喷发前震阶段记录的地震活动进行比较，这一假设得到了加强，该比较揭示了一个与这些低速区重合的无震区域。在该岛南部还观察到另一个低速区，我们将其解释为高度破碎的岩石，这可能有利于热流体的上升。在该岛中部观察到最后一个低速区，它与阿里达内山谷巨型滑坡产生的松散沉积物有关。
