Abstract
This study presents a new method, called the Radial Interpolation Method, to interpolate data characterized by an approximately radial pattern around a relatively constrained central zone, such as the ground deformation patterns shown in many active volcanic areas. The method enables the fast production of short-term deformation maps on the base of spatially sparse ground deformation measurements and can provide uncertainty quantification on the interpolated values, fundamental for hazard assessment purposes and deformation source reconstruction. The presented approach is not dependent on a priori assumptions about the geometry, location and physical properties of the source, except for the requirement of a locally radial pattern, i.e., allowing multiple centers of symmetry. We test the new method on a synthetic point source example, and then, we apply the method to selected time intervals of real geodetic data collected at the Campi Flegrei caldera during the last 39 years, including examples of leveling, Geodetic Precise Traversing measurements and Global Positioning System. The maps of horizontal displacement, calculated inland, show maximum values lying along a semicircular annular region with a radius of about 2–3 km in size. This semi-annular area is marked by mesoscale structures such as faults, sand dikes and fractures. The maps of vertical displacement describe a linear relation between the maximum vertical uplift measured and the volume variation. The multiplicative factor in the linear relation is about 0.3 × 106 m3/cm if we estimate the proportion of the ΔV that is captured by the GPS network onland and we use this to estimate the full ΔV. In this case, the 95% confidence interval on K because of linear regression is ± 5%. Finally, we briefly discuss how the new method could be used for the production of short-term vent opening maps on the base of real-time geodetic measurements of the horizontal and vertical displacements.
Highlights
Ground deformation is a feature constantly and accurately monitored in many active and high-risk volcanic areas (e.g., Palano et al 2008; Fournier et al 2010; Lagios et al 2013; Gonzalez et al 2013; Di Traglia et al 2014; Trasatti et al 2015; Stramondo et al 2016; Chen et al 2017)
ΔV1 considers the envelope of all RIM elliptic arcs, ΔV2 is the sum over a circle of 6 km radius from the averaged center of symmetry, ΔV3 is based on the vertical displacement over a 140° circular sector on the northern side of Campi Flegrei caldera, multiplied by 360°/140°, and ΔV4 considers the portion of this circular sector than is less than 6 km from the center
Whenever there is reasonable evidence of radial symmetry between each pair of measurements, the new interpolation method RIM presented in this study enables the fast construction of ground displacement maps for both vertical and horizontal components
Summary
Ground deformation is a feature constantly and accurately monitored in many active and high-risk volcanic areas (e.g., Palano et al 2008; Fournier et al 2010; Lagios et al 2013; Gonzalez et al 2013; Di Traglia et al 2014; Trasatti et al 2015; Stramondo et al 2016; Chen et al 2017). Significant deformation can take place in response to the injection/removal of magma bodies, magmatic fluids and/ or hydrothermal fluids in the volcanic system (e.g., Acocella et al 2015; de Silva et al 2015; Hildreth et al 2017). Ground deformation can represent a fundamental eruption precursor (e.g., Voight et al 1998, 2000; Cervelli et al 2006; Chadwick et al 2011; Chaussard and Amelung 2012; Robertson and Kilburn 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
