Hypocenter Determination and Uncertainty Analysis Using the Reciprocal Fast Marching Wavefront Modeling (RFMW)
Alfi Nur Albab (a*), Bagus Endar B. Nurhandoko(a)

a) Earth Physics and Complex System Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
*albabalfi938[at]gmail.com

Abstract

Accurate determination of earthquake parameters is vital for seismologists due to their potential hazards and the importance of risk mitigation. Among these parameters, the hypocenter location is especially critical, as it significantly influences seismic tomography and inversion processes.
This study introduces a novel approach for hypocenter localization based on the Reciprocal Method of Fast Marching Wavefront Modeling (RFMW). This method models seismic wavefronts by solving the eikonal equation through the Fast Marching Method (FMM).
We evaluate the effectiveness of RFMW in locating hypocenters within highly heterogeneous subsurface media and in addressing the nonlinear aspects of wave propagation. Additionally, we investigate how hypocenter accuracy is affected by the spatial configuration and distribution of seismograph stations.
The RFMW approach was applied to determine several hypocenters beneath Lake Toba in North Sumatra. Results reveal a strong correlation between the seismograph network configuration-particularly station spacing and distribution-and the accuracy of hypocenter localization. Interestingly, increasing the number of seismographs did not significantly enhance accuracy, highlighting the importance of optimal station placement.

Keywords: Hypocenter accuracy- Wavefront modeling- Reciprocal method- Fast Marching Method

Topic: Earth Physics and Space Science