Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

• Published in: Earth and planetary science letters Vol. 422; pp. 157 - 168
• Main Authors: Bathke, H., Nikkhoo, M., Holohan, E.P., Walter, T.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-07-2015
• Subjects: boundary element modeling; caldera subsidence; InSAR; ring-fault architecture; Tendürek volcano; ring-fault architecture; InSAR; caldera subsidence; boundary element modeling; Tendürek volcano
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2015.03.041

The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a ‘sliding-trapdoor’ ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano's western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that ‘sliding-trapdoor’ ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.
•Modeling of a caldera ring-fault by using InSAR-derived surface displacements.•First BEM model of a ring-fault with variable dip-angle along strike direction.•Asymmetric or sliding-trapdoor ring-fault architecture at Tendürek volcano.•Dip-slip and strike-slip component along ring-fault.•Results confirmed by analog models and compared to other volcanoes in nature.