3D Deep Electrical Resistivity Tomography of the Lusi Eruption Site in East Java

Abstract

Electrical resistivity and magnetotelluric are potential methods often used in hydrogeophysical and geothermal studies. Electrical resistivity tomography is traditionally a shallow-reaching method unless using logistically challenging configurations often prohibitive in urbanized areas. Magnetotelluric enables prospecting much greater depths but it is normally hampering resolution of the shallower data. Both methods are hindered by the electromagnetic noise that is typical of urbanized regions. Hence, the prospection of the upper kilometer of the crust with electrical methods is not trivial. However, Deep Electrical Resistivity Tomography (DERT) has been previously attempted and few successful data acquisition experiments were conducted over the last decade. Revil et al. (2011) investigated the hydrogeology of the Stromboli volcano in Southern Italy with several 2D roll-alongs of multi-core cables with 50 m electrode spacing. Balasco et al. (2011) and Pucci et al. ( 2016) used dipole-dipole and remote electrode configuration, respectively, to attain 2D profiles ∼1,000 m deep to investigate seismogenic structures in the Italian Apennines. Experiments aiming to obtain large-scale 3D images have been attempted by Troiano et al. (2019) who provided a resistive image of the shallow hydrothermal system of the Campi Flegrei, Italy. Such type of studies became possible thanks to IRIS® instruments that released the Fullwaver system (Carrier et al., 2019;Lajaunie et al., 2019;Troiano et al., 2019) equipped with GPS-synchronised voltmeters that can be deployed to form a network even in urbanized areas. This hardware was initially conceived to investigate the chargeability and resistivity contrasts often encountered in ore deposits. However, Carrier et al. (2019) has shown that the Fullwaver technology could also be suitable to prospect middle-enthalpy geothermal environments. Moreover this versatile system can acquire large-scale 3D surveys on active geothermal structures where

Geysers, Boiling Groundwater and Tectonics: The 3D Subsurface Resistive Structure of the Haukadalur Hydrothermal Field, Iceland

“…Byrdina et al (2014)). Only recent studies in high-enthalpy hydrothermal settings (Troiano et al, 2019;Legaz et al, 2009;Millera et al, 2020;Gómez-Ortiz et al, 2014;Mazzini et al, 2021) acquired fully 3D electrical measurements at the meso-scale that are comparable with our investigations.…”

“…R IRIS has recently released the Fullwaver hardware that allows the acquisition of 3D geoelectrical datasets by scattering independent GPS-synchronised volt-meters across the investigated region (e.g. Carrier et al (2019); Lajaunie et al (2019); Sapia et al (2021); Mazzini et al (2021)). Despite the inaccessibility of certain areas (i.e.…”

“…Large prospection depths can be attained by using remote electrodes that require several kilometers of cable (e.g., Pucci et al (2016)). ® IRIS has recently released the Fullwaver hardware that allows the acquisition of 3D geoelectrical data sets by scattering independent GPS-synchronised volt-meters across the investigated region (e.g., Carrier et al, 2019;Lajaunie et al, 2019;Mazzini et al, 2021;Sapia et al, 2021). Despite the inaccessibility of certain areas (i.e., in close proximity to the sinter deposits surrounding the geysers' vents) in June 2018, we deployed the Fullwaver system in the Hhf acquiring resistivity and chargeability data (Figure 2).…”

Electrical Resistivity Survey of the Gunung Anyar Mud Volcano

“…Resistivity methods have also been used to identify the underground structure of mud volcanic layers. According to a study by [13], [14], a resistivity tool (Pseudo3D ERT) combined with a digital elevation model (DEM) can characterize the underground structure of Piparomad Mountain in Trinidad and Tobago. The results showed a low resistivity value (<2.5 ohm.m) in the Mud Volcano sediment flows in the main vent.…”

“…A high resistivity value (>3.2 ohm.m) is a lithofacial structure of sedimentary rocks due to mud deposits around the main hole. Another study was carried out in Mount Volcano Sidoarjo (LUSI) using resistivity methods (3D ERT) by [14]. As a result, the resistivity (3D ERT) shows cross-sectional areas in 0.14-141 ohm.m.…”