Browsing by Author "Iturrieta, P."

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    Earthquakes Trigger Rapid Flash Boiling Front at Optimal Geologic Conditions
    (2024) Sanchez-Alfaro, P.; Wallis, I.; Iturrieta, P.; Rowland, J.; Dempsey, D.; O'Sullivan, J.; Reich, M.; Cembrano, J.
    The interplay between seismic activity and fluid flow is essential during the evolution of hydrothermal systems. Although earthquakes can trigger transient fluid flow and phase changes in dilational jogs, the temporal scale and the geologic conditions that enhance such process are poorly quantified. Here, we use numerical simulations of deformation and fluid flow to constrain the conditions that maximize adiabatic boiling-referred to as flashing-and estimate the extent and duration of such process. We show that there is an optimal geometry for a dilational jog that maximizes co-seismic flashing within the jog. Fluid flow simulations indicate that the duration, intensity, and propagation of the flashing front are limited and highly dependent on the magnitude of the co-seismic slip and the initial pressure-enthalpy conditions. Our results are valuable to better understand the implications of pressure fluctuations during the seismogenic cycle, as well the mineralization processes in the Earth's crust. Earthquakes can strongly affect circulating fluids within the Earth's crust, mainly where faults bend or split into different fault segments and produce dilatant areas. In these areas, earthquakes play an important role in forming ore deposits, because the co-seismic volume change can produce a pressure drop that drives boiling with gas exsolution and subsequent mineralization. This process, in which boiling is triggered by a pressure drop rather than a temperature rise, is called flash vapourization or flashing. Here, we used a computer code to unravel scenarios where optimal geometry and pressure-temperature conditions maximize flash vapourization. Furthermore, we found that the duration and extension of the flashing event are limited and highly dependent on the magnitude of the triggering earthquake and the physico-chemical conditions of the system. Such results are valuable for assessing the implications of pressure fluctuations during the seismogenic cycle and for better understanding mineralization processes in the Earth's crust.
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    Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes
    (2017) Roquer, Tomás E.; Arancibia Hernández, Gloria Cecilia; Rowland, J.; Iturrieta, P.; Morata, D.; Cembrano, José
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    Mapping regional strain in anesthetised healthy subjects during spontaneous ventilation
    (2019) Cruces, P.; Erranz, B.; Lillo, F.; Sarabia-Vallejos, M.A.; Iturrieta, P.; Morales, F.; Blaha, K.; Medina, T.; Diaz, F.; Hurtado Sepúlveda, Daniel
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    Oblique-slip tectonics in an active volcanic chain : a case study from the Southern Andes
    (2019) Sielfeld Corvalán, Gerd Gustav; Ruz, J.; Brogi, A.; Cembrano, José; Stanton-Yonge, A.; Perez-Flores, P.; Iturrieta, P.
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    Reactivation of Fault Systems by Compartmentalized Hydrothermal Fluids in the Southern Andes Revealed by Magnetotelluric and Seismic Data
    (2020) Pearce, R. K.; Sanchez de la Muela, A.; Moorkamp, M.; Hammond, J. O. S.; Mitchell, T. M.; Cembrano, J.; Araya Vargas, J.; Meredith, P. G.; Iturrieta, P.; Perez-Estay, N.; Marshall, N. R.; Smith, J.; Yanez, G.; Ashley Griffith, W.; Marquardt, C.; Stanton-Yonge, A.; Nunez, R.
    In active volcanic arcs such as the Andean volcanic mountain belt, magmatically sourced fluids are channeled through the brittle crust by faults and fracture networks. In the Andes, volcanoes, geothermal springs, and major mineral deposits have a spatial and genetic relationship with NNE trending, margin-parallel faults and margin-oblique, NW trending Andean Transverse Faults (ATF). The Tinguiririca and Planchon-Peteroa volcanoes in the Andean Southern Volcanic Zone (SVZ) demonstrate this relationship, as their spatially associated thermal springs show strike alignment to the NNE oriented El Fierro Thrust Fault System. We constrain the fault system architecture and its interaction with volcanically sourced hydrothermal fluids using a combined magnetotelluric (MT) and seismic survey that was deployed for 20 months. High-conductivity zones are located along the axis of the active volcanic chain, delineating fluids and/or melt. A distinct WNW trending cluster of seismicity correlates with resistivity contrasts, considered to be a reactivated ATF. Seismicity occurs below 4 km, suggesting activity is limited to basement rocks, and the cessation of seismicity at 9 km delineates the local brittle-ductile transition. As seismicity is not seen west of the El Fierro fault, we hypothesize that this structure plays a key role in compartmentalizing magmatically derived hydrothermal fluids to the east, where the fault zone acts as a barrier to cross-fault fluid migration and channels fault-parallel fluid flow to the surface from depth. Increases in fluid pressure above hydrostatic may facilitate reactivation. This site-specific case study provides the first three-dimensional seismic and MT observations of the mechanics behind the reactivation of an ATF.
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