A problem of the hypocenter determination in the time of few seismic stations

―A case of the 1936 Chirisan earthquake in Kyongsangnam-do, Korea―

Abstract

As seismic stations were few before the establishment of modern seismic monitoring system, it was difficult to determine hypocenters. Japan Meteorological Agency (JMA) misdetermined the 1936 event at the east off Korean peninsula, although the true location was at the south of the Korean peninsula. This study researches the mislocation of the1936 event by JMA. As the result, it is clarified that effective use of the distribution of seismic intensity and P wave arrival directions in addition to data of P and S wave arrival times is important to determine hypocenters correctly for earthquakes in the early twentieth century.