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Structural control of subsurface processes using a finite-element-based dynamic model of mid and short-term crustal evolution at Krafla volcano.

Ana Martinez-Garcia1, Joachim Gottsmann2, James Wookey1, Alison Rust1.

  • Affiliations: 1 University of Bristol, Bristol, United Kingdom; 2 Ludwig-Maximilians Universität, München, Germany

  • Presentation type: Talk

  • Presentation time: Friday 10:30 - 10:45, Room R380

  • Programme No: 2.3.7

  • Theme 2 > Session 3

Abstract

The Krafla Volcanic System (KVS) in northeast Iceland has been one of the world's most studied volcanoes since its last eruption, the Krafla Fires (1975-1984), and during its on-going geothermal exploitation. In 2009, the Icelandic Deep Drilling Project (IDDP) discovered a previously undetected shallow rhyolitic magma body despite extensive studies in the area using geophysical methods. The large gravity and ground deformation dataset compiled at the KVS since 1975 provides unprecedented insights into the evolution of the magmatic and hydrothermal systems. While the eruptive period has been extensively studied using geophysical methods such as ground deformation, seismology, and gravity, the relationship between the magmatic system's evolution and changes in the gravitational potential field remains poorly understood. To understand the structural control of the KVS, we build a 3D finite element model of the gravitational and ground deformation changes caused by the magma infill and withdrawal from a shallow reservoir. We impose a crustal structure using observed topography and assuming a layered medium derived from seismic tomography. Testing different source geometries of the shallow reservoir allows us to replicate better the gravity and height changes observed during the eruptive event. Subsequent work aims to establish plausible combinations of dimensions and density contrast of the magmatic body encountered by the IDDP-1 from gravity measurements. The findings will enhance our understanding of the structural control of the magmatic system at the KVS and may provide valuable insights for future geothermal exploration projects.