Accurately locating microseismic events is critical for developing and monitoring Enhanced Geothermal Systems (EGS). While Distributed Acoustic Sensing (DAS) offers unprecedented spatial density, its application is often hindered by low signal-to-noise ratios and the inherent cylindrical symmetry of vertical fiber deployments, which results in azimuthal ambiguity. Conversely, downhole inertial geophone array provide reliable directional constraints but suffer from sparse spatial coverage.

We introduce a hybrid, picking-free source-imaging approach that integrates these complementary technologies to achieve high-resolution, three-dimensional localization. Our methodology employs a back-projection and stacking workflow (Source-Scanning Algorithm) that jointly analyzes P- and S-wave arrivals. To facilitate this integration, we transform raw seismograms into Short-Term Average/Long-Term Average (STA/LTA) characteristic functions. This step significantly enhances P-wave detectability and stabilizes the signals for coherent stacking. Crucially, we incorporate the co-located 3C geophone data by computing the vector norm, allowing the directional inertial measurements to be seamlessly combined with the scalar DAS strain-rate data.

Applied to 2,680 events from the 2024 FORGE stimulation, this hybrid framework demonstrates superior performance over single-sensor methods. The inclusion of geophone array effectively breaks the cylindrical symmetry of the vertical DAS fiber, resolving azimuthal ambiguity, while the dense DAS aperture sharply focuses the source depth and distance. The resulting high-resolution event clusters reveal detailed fracture growth patterns across three distinct stimulation stages, providing crucial insights into reservoir geomechanics and highlights the potential of complimentary use of DAS and inertial sensors