New ground-motion prediction equations for significant duration of shallow crustal and upper mantle earthquakes in Japan and intra-event spatial correlation

Several models have been proposed and developed to formulate prediction equations for the significant duration (DS) of shallow crustal and subduction earthquakes. However, no equation for DS and a corresponding spatial correlation model have been proposed for upper mantle earthquakes. To address records are selected from the Kyoshin network (K-net) and Kiban Kyoshin network (KiK-net) databases in this study for shallow crustal and upper mantle earthquake with moment magnitudes of 4 ≤ Mw ≤ 7.3, rupture distances Rrup ≤ 300 km and peak ground accelerations (PGAs) ≥ 0.01 g. A new prediction equation is established for DS of shallow crustal and upper mantle earthquakes in Japan by considering the influences of Mw, Rrup, the time-averaged shear-wave velocity to 30 m VS30, the difference between the measured and predicted values of the overburden thickness for a shear wave velocity of 1000 m/s δZ1, and the depth to the top of the rupture Ztor on the DS of ground motion. The rationality and reliability of the proposed prediction model is confirmed using residual analysis and by comparison with existing prediction models. Based on intra-event residuals and single-station intra-event residuals, a semivariogram function and exponential model are used to analyze the spatial correlation of DS, which provides a reference basis for the development of GMPEs based on the nonergodic hypothesis, and regional seismic risk analysis and loss assessment.