Ground-motion attenuation relationships for subduction-zone earthquakes in northeastern Taiwan

Subduction zone earthquakes have not been taken into special consideration in most previous probabilistic seismic hazard analyses (PSHA) in Taiwan. However, they may be critical to properly analyze the earthquake hazard in metropolitan Taipei, so they need to be studied. Strong-motion data from subduction zone earthquakes, of both interface and intraslab types, obtained by the TSMIP and SMART1 arrays in northeastern Taiwan, are used to establish the attenuation equations for peak ground acceleration (PGA) and response spectral acceleration (SA). The resultant PGA and SA attenuation equations include two site classes and two earthquake source types. The ground-motion values predicted by these attenuation equations are higher than those obtained from the crustal earthquake attenuation equations previously used in Taiwan but are lower than those predicted by the attenuation equations for worldwide subduction zone earthquakes.