Lusi, the youngest sediment-hosted geothermal system on Earth, pierced the surface in May 2006 in the Kendeng Basin (East Java). To investigate the subsurface and the fluid migration pathways feeding this large eruptive center we processed a dataset of seismic ambient noise. We compared the intrinsic attenuation distribution and the S-wave velocity structure of a region of the Javanese back-arc basin against its shear wave velocity structure. Our study highlights that Lusi’s plumbing system features two distinct fluid flow regimes, one across the shallow sedimentary units and one developing sub-vertically across the deeper domains of the basin. We show that ambient noise and intrinsic attenuation tomographies are complementary tools that should be performed routinely when studying geothermal systems. For decades, this region has been considered a hydrocarbon province as shown by the dozens of wells extracting hydrocarbons form the reservoirs. However, we instead highlight that such a basin is rich in geothermal resources. In particular, we argue that since the hydrocarbon extraction is declining and the energy transition is becoming imperative, the available hydrocarbon facilities should instead be repurposed for the extraction of geothermal resources. The high geothermal gradient, the steep topography of the nearby volcanic arc driving fluid flow and the well-studied subsurface, make this portion of the Kendeng basin an excellent geothermal site. Furthermore, the abundant geothermal resources at depth could be harnessed by re-purposing the dozens of wells drilled in the depleted oil and gas fields. Future geothermal operators should capitalize on existing infrastructure and turn the Lusi natural disaster into a geothermal opportunity.