Normal vector analysis from GNSS—GPS data applied to Deception volcano surface deformation

Abstract

SUMMARY Surface deformation parameters and its use in volcano monitoring have evolved from classical geodetic procedures up to those based on Global Navigation Satellite Systems (GNSS), in particular the most widely used and known Global Positioning System (GPS), profiting from the automated data processing, positioning precision and rates, as well as the large storage capacity and low power consumption of its equipments. These features have enabled the permanent GNSS–GPS data acquisition to ensure the continuous monitoring of geodetic benchmarks for the evaluation of surface deformation in active tectonic or volcanic areas. In Deception Island (Antarctica), a normal vector analysis is being used to give surface deformation based on three permanently observed GNSS–GPS benchmarks. Due to data availability, both in the past and for near real‐time use, all benchmarks used are inside the monitored volcanic area, although the reference is away from thermal springs and/or fumaroles, unlike the other two. The time variation of slope distances to the reference benchmark and of the magnitude and inclination of the normal vector to the triangle defined by the reference benchmark and any other two, provides the spatial deformation in the volcanic area covered. The normal vector variation in magnitude gives information on compression or expansion, here called spatial dilatometer, while the changes in inclination gives information on relative uplift or subsidence, here called spatial inclinometer. In geodesy, the triangle is a basic geometric unit and the areal strain is commonly applied in tectonics and volcanism. The normal vector analysis conjugates both, benefiting from the method's precision, simplicity and possibility to model the surface using several triangles. The proposed method was applied to GNSS–GPS data collected every austral summer between 2001–2002 and 2009–2010 in Deception Island. The results evidence that Deception Island acts as a strain marker in the Bransfield Basin volcano‐tectonic setting.

Geodetic implications on block formation and geodynamic domains in the South Shetland Islands, Antarctic Peninsula

“…While the former exhibits nearly linear trends, particularly concerning its horizontal position components, the latter shows less linear trends in both horizontal and vertical position components. This is interpreted to be mostly due to Deception Island's volcanic activity (Berrocoso et al, 2006;Berrocoso et al, 2012;Carmona et al, 2012;García et al, 2002;Ibañez et al, 2000;Ibañez et al, 2003;Prates et al, 2013).…”

“…Geometrical relationships between the location and orientation of joints and faults indicate two evolutionary phases, implying a counter-clockwise rotation of Deception Island which might be related to regional left-lateral strike-slip movements. In recent years the geodetically inferred NNE-SSW compression rate was higher than the NNW-SSE extension rate at Deception Island (Berrocoso et al, 2012;Prates, 2012;Prates et al, 2013). Recent paleostress regimes were determined for Deception Island (Maestro et al, 2007) and Byers Peninsula on Livingston Island (Alfaro et al, 2010), showing similar patterns following a NNW-SSE to NNE-SSW extension related to the Bransfield Basin opening and left-lateral transtension at the Antarctic-Phoenix boundary, as well as NE-SW and NW-SE compressional states related to the Antarctic-Scotia convergence and the Phoenix Microplate subduction, respectively.…”

The 3D Attenuation Structure of Deception Island (Antarctica)

“…Additionally, geochemical analysis of the composition and ratio of stable isotopes and gases produced by fumaroles (Caselli et al 2004(Caselli et al , 2007Kusakabe et al 2009) are also very well known and provide important information on the presence and origin of magma and fluids. Nowadays, with these observables, the research community is working to provide a geodynamic and volcanological model that could unify all of them in a single interpretation, such as those made by Smellie (2001), Martí et al (2013), Berrocoso et al (2012) and Pedrera et al (2012).…”

Integrated velocity field from ground and satellite geodetic techniques: application to Arenal volcano

“…In the case of Arenal volcano, the deformation occurs at a constant rate, so it is appropriate to use a linear regression to compute the time-series. When velocities are not constant, the method could be extended using a Kalman filter (Dong et al 1998;Fournier et al 2009;Shirzaei & Walter 2010;Berrocoso et al 2012). …”

“…Numerous methods exist for both 3-D point-based and temporal measurements, with the choice of method depending on the size of the data set and the complexity of the temporal deformation (e.g. Dong et al 1998;Berrocoso et al 2012;Fournier et al 2009, or for InSAR Berardino et al 2002Hooper et al 2004). …”