1991 年 44 巻 Supplement 号 p. 329-340
Recently, telemetered microearthquake observation networks have been developed, and data acquisition and processing procedures have been automated in many networks, including automatic hypocenter determinations by using computers. As a result the detection capability and the accuracy of hypocenter determination of microearthquakes have been tremendously improved, which made a great advance in detailed microearthquake studies. We present a brief review on recent studies of seismicity based on microearthquake observations, focusing on spatial and temporal distributions of microearthquakes and their related problems.