LAUSR

Timely and accurate estimation of earthquake moment magnitude (Mw) is crucial for damage assessment and emergency response. However, obtaining reliable Mw estimates within approximately 10 min of origin time remains challenging. In this study, we present a novel and robust algorithm for Mw estimation of moderate-to-large earthquakes using regional to teleseismic records. The method was applied to 22 earthquakes (Mw≥6.5, depth ≤ 60 km) in western China from 2008 to 2023. Magnitude estimates were obtained within ∼6 to 11 min after origin time and agree with U.S. Geological Survey values, with a standard deviation of ∼0.1. The estimates remain robust and stable despite variations in the number and spatial distribution of contributing stations. The algorithm mitigates contamination from reflected phases in regional data and uneven station distribution by employing adaptive time windows and spatial averaging of P-wave amplitudes in azimuth and take-off angle grids. Backprojection yields robust estimates of source durations even with relatively sparse seismic array coverage. However, larger events may require denser station spacing and wider apertures to suppress interfering phases in regional to teleseismic waveforms. Comparative analysis with widely used magnitude scales, such as broadband surface- and body-wave magnitude scales, further confirms the method’s stability, demonstrating its potential as a rapid, reliable complement to existing real-time magnitude estimation techniques.