The Shanxi reservior is located in the Wenzhou city of Zhejiang province

the dam height and the storage of this reservoir are 138. 4 m and 1432 million m3 respectively. A reservoir-induced earthquake ML 3. 5（July 28

2002） took place in this reservior area. Afterwards

more than 50 aftershocks（ML≥1. 0） have been recorded in this area. The earthquake ML 3. 9 occurred in September 5

2002 is the most strong earthquake of the sequence.Soon after the significant earthquake ML 3. 5 occurred

we were doing rapid follow-up prediction for the post-seismic tendency applying the fuzzy soft cluster method after the occurrence of significant earthquake. At first

some data of earthquake sequences should be selected as samples to determine the classification standard of earthquake magnitude in accordance with the demand of prediction

and build the classification matrix. Then

the 6 seismicity indexes of every sample sequence and the latest earthquake sequence are calculated to build the sample matrix and the wait-judge matrix respectively. By judging these data with application of fuzzy soft cluster

it can be known which class of earthquake will take place in some term of future. If sample matrix and classification matrix for different prediction terms are built with data of different time section

the rapid prediction of follow-up post-seismic tendency will be achieved. The prediction of the ML 3. 9 and the rapid judgement of post-seismic tendency were relatively precise. In this article

this method of prediction and its effects are introduced briefly.