Journal Article

Ambient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal Array

Calò, Marco, Ventura, Guido, Persaud, Patricia, Di Luccio, Francesca

2023

Overview

We applied ambient noise tomography to continuous data recorded by a dense seismic array deployed on the volcanic island of Lipari in the southern Tyrrhenian Sea. Since most of Lipari's seismicity occurs offshore and is not evenly distributed, this technique allowed us to obtain the first high‐resolution images beneath the island down to ∼2.5 km depth. Results show a complex seismic structure related to the various ages and compositions of the volcanic products characteristic of the different regions of the island. High shear wave velocities are found in western Lipari, where active hydrothermal vents and N‐S faults are mapped. Low wave speeds are revealed beneath southern and northeastern Lipari, where more recent volcanic activity developed along N‐S dike‐like structures that are aligned with rhyolitic vents. We suggest these dikes likely represent the probable pathways of future volcanic eruptions. Plain Language Summary Recordings of Earth's background seismic noise from an array of tightly spaced instruments allow us to decipher the rocks beneath Lipari, a 37‐km2 active volcanic island in the southern Tyrrhenian Sea. In 2018, for the first time, 48 compact seismic instruments were installed on the island providing continuous recordings for about 1 month that are now used to produce the first three‐dimensional model of the volcano down to ∼3 km depth. The high‐resolution images of Lipari show complex features that are related to the different types and ages of the volcanic rocks. Active CO2‐rich fumaroles and faults found at the Earth's surface are imaged down to depths between 0.5 and 3 km. Beneath southern and northeastern Lipari, conduits of the younger N‐S aligned vents are revealed in the images and they may represent the shallower feeding system of future volcanic eruptions. With the new information from seismic imaging, we are able to better understand the three‐dimensional architecture of the volcanic system and faults, which combined with surface observations will allow us to more accurately determine the potential for future activity and estimate eruptive style and minimum volumes of the eruptive products. Key Points Dense nodal array probes the underground plumbing system of active volcanic islands Ambient noise tomography reveals the complexity of the spatio‐temporal relationship between volcanic, structural, and hydrothermal features High and low shear wave velocities are linked to different eruptive epochs of volcanic edifices in the southern Tyrrhenian Sea

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Ambient noise / ambient noise tomography / Arrays / Background noise / Carbon dioxide / Depth / Dikes / Earth surface / Embankments / Fault lines / Faults / Hydrothermal vents / Instruments / Lava / Lipari / Offshore / Resolution / Rocks / S waves / Seismic activity / Seismic arrays / seismic dense array / Seismic velocities / Seismicity / Shear wave velocities / Tomography / Vents / Volcanic activity / Volcanic eruptions / Volcanic islands / Volcanic rocks / volcanic structure / Wave velocity