A Finite-Domain Robust Framework for Effective Wave-Velocity Calibration and Microseismic Source Location in Meter-Scale Rock Specimens

Locating fracture activity inside meter-scale rock specimens requires converting recorded wave arrivals into reliable source coordinates. In practice, this process is affected by uncertainty in wave velocity, abnormal arrival picks, incomplete sensor coverage, and the finite size of the specimen, which can lead to unstable or physically unreasonable locations. To address these issues, this study develops a finite-domain robust microseismic localization framework that integrates effective-velocity calibration, constrained source location, and robust treatment of abnormal observations within a unified workflow. The method was evaluated using controlled synthetic benchmarks covering different disturbance levels, propagation conditions, and timing errors. The results show that the proposed framework improves source-location accuracy and reduces large localization errors, with the clearest advantage under strongly disturbed arrival-time conditions and for events located near specimen boundaries. Additional sensitivity analyses demonstrate how propagation structure, sensor timing, and array configuration affect the estimated locations and effective velocity. The resulting workflow provides a reproducible and standardized approach for arrival-time-based microseismic localization in meter-scale rock specimens and offers a consistent basis for subsequent fracture interpretation and laboratory monitoring.