Ground-Motion Relations for Subduction-Zone Earthquakes in Java Island, Indonesia

Predictive relations are presented for peak ground acceleration and 5% damped response spectral acceleration at frequencies of 1, 2 and 5 Hz for subduction-zone earthquakes in Java Island. The dataset includes 1825 strong-motion recordings from 152 subduction-zone earthquakes of moment magnitude (M) 4.8–8.6 that occurred between 2008 and 2013. The data include 42 additional events from Sumatra subduction zones. The predictive relations are developed for both interface and in-slab events on rock sites (B and C class) and soil sites (D and E class). These relations are important because Java Island is a seismically active and densely populated region in Indonesia and no region-specific ground-motion relations have been developed yet for the island. The available relations (i.e., Atkinson and Boore in Bull Seismol Soc Am 93:1703–1729, 2003; Youngs et al. in Seismol Res Lett 68(1):58–73, 1997) were found to be unreliable in predicting previously recorded subduction events in Java Island. Thus, we undertook this study to develop ground-motions relations specific to Java Island. Our predictions are generally lower than those predicted by Youngs et al. (Seismol Res Lett 68(1):58–73, 1997) and significantly higher for moderate events than those of Atkinson and Boore (Bull Seismol Soc Am 93:1703–1729, 2003. Predicting ground shaking is a key step in anticipating earthquake effects in the region. The ground-motion predictive relations developed in this study can be used in probabilistic seismic hazard assessment studies in Java Island.