Abstract: The real-time processing system of NCDSN (National Center of Digital Seismic Network) is an important component part of NDSN. The main functions of the software system are: real-time collection and storage of seismic wave data of the 47 national digital seismic stations, real-time detection of seismic events, automatic earthquake location, earthquake alarm, and man-machine interactive precision earthquake location. The system is capable of rapidly determining the epicenter and magnitude of earthquakes, which are M_S≥5.0, M_S≥6.0, and M_S≥7.0 for domestic, neighboring and world-wide ones respectively. The main features of the system are as follows: the system is a hot standby one. It has a good real-time ability, high reliability, stability and availability, owing to using very good prog ramming technologies. Some new methods of earthquake location are adopted, such as geometric pattern of analytical method of earthquake location, method of earthquake location of intersect of circles and hyperbolas. Mani fold methods of earthquake location are generalized to a unified approach, which develops the theory of earthquake location. The methods is used in the program of earthquake location, good results are obtained. The operation of man-machine interactive system is easy to use. The information of the seismic graphics and data is abundant, which is conductive to analyze seismic waveform and determine epicenter parameters. The system is a good computer aided thought and analysis one.

Key words: Seismic monitoring, Seismic location, Computer real-time processing, Man-machine interactive processing