<i>P</i>/<i>SV</i> Amplitude Ratios of Shallow Isotropic Explosions and Earthquakes Could Be Indistinguishable at Local Distances: Insights from Single-Station Waveform Simulations

Abstract Shear waves play a key role in seismic discrimination between explosions and earthquakes due to their different source mechanisms. However, shear are often observed field with unexpectedly large amplitude, generation mechanism is still significant unresolved question seismology. Many explanations have been proposed, including the asymmetry of explosive sources, heterogeneity and/or anisotropy Earth’s subsurface. it has not well understood whether or velocity structure can independently sufficiently explain generated by explosions. Theoretically, tangential SH be converted scattered from vertical radial SV heterogeneity. Thus, essential understand In this study, we utilize frequency–wavenumber algorithm 1D layered models simulate waveforms isotropic double-couple at local distances (&amp;lt;20 km). Our results suggest that may generate comparable if both occurred within near-surface gradient zone. The earliest appear originate near-source region. It implies P/SV amplitude ratios could indistinguishable under certain circumstances.