EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

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

Adriano Mazzini1, Aurore Carrier2, Alessandra Sciarra3, Federico Fischanger4, Anton Winarto-Putro5, and Matteo Lupi2
Adriano Mazzini et al.
  • 1CEED - University of Oslo, CEED, Department of Geology, Oslo, Norway (
  • 2Department of Earth Sciences, University of Geneva, Geneva, Switzerland
  • 3Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
  • 4Geostudi Astier srl, Livorno, Italy
  • 5Pusat Pengendalian Lumpur Sidoarjo (PPLS), Sidoarjo, Indonesia

Lusi is the nickname of the largest sub-aerial erupting clastic system on Earth. This sediment-hosted geothermal system relentlessly erupts since May 2006 in the East Java back-arc sedimentary basin. This spectacular system features two main active craters (~100 m in diameter each) surrounded by thousands of satellite active seeps that extend over a region of 7km2. Previous multidisciplinary studies revealed that Lusi is connected at depth with the neighboring Arjuno-Welirang volcanic complex through a system of faults (Watukosek Fault System) that extend from the volcano towards the north in the sedimentary basin. The migration of these mantle-derived fluids feeds the long-lasting activity of the eruption. Vigorous convection fuels the system and leads to geyser-like eruptive activity.

To investigate the morphology and the effect that pre-existing geological structures may have on the development of the shallow plumbing system of Lusi, we deployed a pool of 25 IRIS V-Fullwavers to conduct a 3D deep electrical resistivity tomography extending over 15 km2 around the eruption site. The inverted data reveal the structure of the subsided area hosting the region where a mix of groundwater, mud breccia, hydrocarbons and boiling hydrothermal fluids are stored. We estimate that after 12 years of Lusi's inception, a collapse region of 0.6km2 developed around the active vents. Combining the flow rate data with our geoelectrical data, we estimate a total budget of 0.47km3 of mud breccia (i.e., including the erupted volume and that trapped in the collapse zone around the carter). Our investigation also points out the link between the well-developed Watukosek Fault System and the upwelling of the deep-sourced fluids that initiated, and still drive, the development of the new-born Lusi eruption. Lusi provides the unprecedented opportunity to study the development of the early phases of a piercement structure and its impact on society. Our study highlights how fully 3D geoloectrical methods may represent a key tool to investigate and possibly mitigate geohazards.

How to cite: Mazzini, A., Carrier, A., Sciarra, A., Fischanger, F., Winarto-Putro, A., and Lupi, M.: 3D Deep Electrical Resistivity Tomography of the Lusi Eruption Site in East Java, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5960,, 2022.