Abstract: Seismic activity patterns before M_S≥5.5 earthquakes in the southeastern China since 1970 are analyzed. It is found that varying degrees of seismic strips, gaps and enhancements have been found before the earthquakes There are four strips, three gaps and four enhancements appeared out of nine events, and more than two kinds of anomalies appeared before the four mainshocks. Relative positions of strips, gaps and mainshocks show that the ratio of mainshocks located in the strip is equivalent to the margins or outside,and the mainshocks are all located in the gap. The ratio of angle between strip, gap and causative fault strike within 30° is 33% and 60% respectively.

Key words: Earthquake activity pattern, Seismic gap, Seismic strip, Southeastern China