Expanding moment magnitude dataset for earthquake magnitudes homogenization

Abstract

To enhance the seismicity analysis within a given seismic region, it is crucial to establish a unified earthquake catalog with minimized uncertainties. The preparation of such a unified catalog needs scaling relationships to convert different magnitude types to a homogeneous magnitude. Among the plethora of magnitude types, the moment magnitude (M_w) stands out as a widely utilized metric in modern earthquake risk and recurrence analysis. Hence, the key objective of this study is to expand the M_w earthquake dataset specifically for the Northern Algeria region and its surrounding areas, providing a valuable resource for researchers investigating seismicity in this region and for earthquake magnitudes homogenization. To achieve this objective, surface wave (M_s) and body wave (m_b) magnitudes obtained from international agencies were standardized to M_w using newly developed regional empirical relationships based on the general orthogonal regression method (GOR). The use of GOR for magnitude conversions has gained popularity in recent years. However, a critical aspect when employing the GOR method is estimating the standard deviations associated with different magnitude types and subsequently determining the error variance ratio. To address this, the present study leverages recent research works to approximate the standard deviations associated with various magnitudes. By calculating the error variance ratio, derived from the estimation of magnitude uncertainties, the general orthogonal regression method was effectively applied to achieve the desired earthquake magnitude homogenization. Notably, this study fills a significant gap in research conducted in Algeria by developing regional empirical relationships using GOR with appropriate values of the error variance ratio. The expanded M_w dataset serves as a dependable resource used for other earthquake magnitudes homogenization, hence the preparation of a more extensive and unified M_w earthquake catalog for Northern Algeria and its neighboring areas.