Tilt measurements at Vulcano Island

Abstract

A network of tiltmeters has been operational on Vulcano Island for numerous years. At present, the network comprises five functioning borehole stations, four of which are installed at 8-10 m and allow recording very stable, high precision signals with very low noise. We report observations over the last 12 years that illustrate impulsive variations linked to seismicity and long-term (several years) trends in the signals. We suggest a relationship between tilt changes correlated to the strongest regional seismic events and site acceleration; long-term tilt variations analyzed in combination with other ground deformation data seem to represent evidence of a contraction of the La Fossa cone. We also analyzed how the tilt device has the capability to detect possible magma migrations; we considered previous studies that have imaged spatially well-defined levels of magma accumulation beneath La Fossa, and Vulcanello; we concluded that the Vulcano tilt network should be capable of detecting the upward migration of small magma volumes. Finally, we show that no evidence of changes are visible on tilt signals during anomalous degassing episodes (linked to a building up input of magmatic fluids) at the La Fossa thereby evidencing that no magma migration occurred during such events.

Detection of Subtle Thermal Anomalies: Deep Learning Applied to the ASTER Global Volcano Dataset

“…The amount of rainfall can affect the thickness of the conductive layer. However, tiltmeters also show some seasonal trends [28], consistent with the solar thermal radiation causing a thermoelastic effect measured by sensors that could be due to displacements of underground masses, e.g. aquifers [27].…”

Mt. Etna Tilt Signals Associated with February 6, 2023, M=7.8 and M=7.5 Turkey Earthquakes

“…Etna by the INGV-OE from the late 1970s, by using bubble borehole tiltmeters [25,26]. Up to the early 2000s, signals from tiltmeters (AGI Mod 722 and Mod 510) in holes between 2 and 4 meters deep were affected by environmental noise (e.g., [27]).…”

Insights Into Hydraulic Fracture Growth Gained From a Joint Analysis of Seismometer‐Derived Tilt Signals and Acoustic Emissions

“…Usually, tilt‐induced signals are attributed to very local effects during the passage of seismic waves (e.g., grains of sand breaking or moving below a seismometer foot or fatigue cracks inside the concrete instrument pier) and need to be corrected before earthquake source studies (Zahradník & Plešinger, 2005, 2010). In volcanic settings, however, near‐field rotational motion has been associated with large‐scale fluid processes like dyke intrusions (e.g., Battaglia et al., 2000; Gambino et al., 2007) or the inflation of magma chambers (e.g., Aoyama & Oshima, 2008; Genco & Ripepe, 2010; Wielandt & Forbriger, 1999; Wiens et al., 2005). Hydraulic fractures induced by fluid injections from boreholes generate similar, although much smaller, tilt signals.…”