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Seismic Imaging of the Solfatara Volcano (Southern Italy) and Characterization of the Very Shallow Fluids Accumulation Zone.

Description: 

Nowadays, the use of active seismic is fundamental and particularly challenging for the imaging of volcanic structures. The use of refraction and reflection phases allows for imaging the shallow structures and sometimes even determining the characteristics of the fluids.The case study of the Solfatara crater was particularly challenging for these purposes. The Solfatara is a quiescent volcano belonging to the Campi Flegrei (Italy), a resurgent nested caldera that has been extensively investigated through active seismic investigation. During the active experiment RICEN (Repeated Induced Earthquake and Noise) performed in the context of the EU project MEDSUV between May and November 2014, two 400 m long profiles were acquired. The seismic arrays were deployed along the NE-SW and NW-SE directions within the crater across the zones of the fumaroles and the “fangaia”. The main fumaroles, Bocca Grande and Bocca Nuova represent some of the most apparent evidence of deep magmatic-hydrothermal activity. In particular, we first performed a refraction non-linear tomographic imaging to characterize the very shallow layer of the crater using a Bayesian estimation of the P-wave velocity model. Subsequently, seismic reflection imaging was performed to investigate the subsoil at greater depths and locate the main structure and possible pathways for the gas ascent. In particular, we got advantages of the seismic attributes such as energy, root mean square, envelope, and sweetness for determining the maximum and minimum values of amplitude zones on the migrated, post-stack seismic sections. Finally, to better characterize the reflectivity of shallow events, enhanced by the post-stack attributes, the Amplitude Versus Offset (AVO) technique has also been used to discriminate and identify shallow gas pockets. The final multi-2D seismic profiles were combined into a final structural image of the Solfatara subsoil. This shows clear evidence of the fluids contact trapped zones at 10-50 m depth beneath the crater's surface and their migration paths down to 150 meters depth.

Session: Crustal Imaging of High Seismic Hazard Regions

Type: Oral

Date: 4/20/2023

Presentation Time: 10:00 AM (local time)

Presenting Author: Sergio Gammaldi

Student Presenter: No

Invited Presentation: Yes

Authors