On Importance of Seismic Phase Weighting in Earthquake Location Problem

Accurate seismic source location is a critical endeavor in seismology, essential for precisely determining the origin of seismic events. Various methods are available for pinpointing seismic sources, each exhibiting varying degrees of accuracy and reliability. In this study, our objective is to assess the influence of seismic phase weighting on earthquake location by comparing the outcomes of three distinct earthquake location programs. To achieve this, we generated two synthetic earthquake catalogs employing a sophisticated ۳D velocity model and a seismic network comprised of ۱۵ stations. We intentionally introduced two synthetic faults, each with different orientations, situated to the south and north of the network. On these fault surfaces, we distributed ۱۰۰ synthetic earthquakes. We then utilized the phase arrivals of these synthetic events to construct both unweighted and weighted catalogs. Weighting was assigned based on errorcalculations and local noise models unique to each station. Our findings reveal that the incorporation of appropriate data weighting during the phase reading stage significantly enhances the accuracy of earthquake location, resulting inreduced errors and uncertainties. Among the three programs we compared, HypoDD demonstrated the best performance, successfully determining earthquake locations with minimal localization errors. In the comparison between Hypocenter and Hypo۷۱, the latter's robust outlier detection algorithm proved advantageous in estimating hypocentral errors, even in the presence of outliers. When examining the results obtained from the weighted catalogs, both programs yielded similar outcomes when the data were appropriately weighted, underscoring the crucial role of proper data weighting in achieving consistent performance.

Keywords:

seismic phase , weighting , earthquake location , location accuracy , synthetic test