SEGJ Technical Conference

Raipid estimation of epicentral distance by growing initial P-wave considering regionally different heterogeneities

Abstract Epicentral distance is estimated from growing curves of initial P-wave in the Earthquake Early Warning system in Railways. This estimation is based on the simple one-to-one relationship between P-wave amplitude and epicentral distance that the P-wave amplitude decreases as the epicenter is farther, which is due to geometrical spreading, scattering and intrinsic attenuation. However in practice, the estimated epicentral distances from the P-wave amplitude include a considerable error, which sometimes reaches 102 km order. In this study we reveal that the error is due to regional difference in heterogeneous conditions. The regionally different heterogeneities scatter and absorb P-wave amplitude in the different manners. We propose a robust method to estimate epicentral distance considering the regional heterogeneous condition.