Reassessment of pre-digital era Indonesian earthquakes

Abstract

We present a re-evaluated dataset of instrumentally determined epicentral parameters and surface-wave magnitudes (MS) for the region of Indonesia for pre-digital era earthquakes up to 1950. We relocated earthquakes using phase data preserved in old station bulletins before verifying these locations with macroseismic observations and or with geological observations. Our investigations show that in most instances, we could improve instrumental locations guided by macroseismic data. Unsurprisingly the largest discrepancies between macroseismic and instrumental locations were for earthquakes in the early years of instrumentation (i.e., up to the mid-1920s). Such discrepancies are likely due to the low number of instrumental observations and their accuracy, as well as the unbalanced azimuthal coverage of the extant global network in the early years of the last century, which was characterized by a scarcity of seismic stations outside Europe. Show more