Characteristics of seismic energy release of subduction zones—examples from Taiwan

Abstract

The characteristics of seismic energy releasing for oceanic subduction and continental collision or subduction zones were explored by a proposed observational approach based on contour maps of seismic energy release on both horizontal and vertical planes, magnitude–energy curve and magnitude–energy–time relationship. It was found that distinct features of energy-releasing behavior exist for the two types of subduction. The oceanic subduction tends to have a more active background noise by continuously emitting small magnitude earthquakes and to release energy from a wider range of depth owing to the existence of subducted plate. On the other hand, surficial strata of a continental subduction tend to release almost all of the seismic energy through a major earthquake with relatively much less long-term noise. Meanwhile, several seismic gaps have been found based on the proposed release energy contour. Together with the tectonic framework and the regional geologic setting, these gaps potentially may involve aseismic zones (e.g., accretionary deposit) or zones awaiting to release its accumulated energy (e.g., the upper crust). The quite zones prone to yielding major earthquakes are accordingly highlighted for a further study.