我国流动重力监测预报发展之再思考

主要分析2008年以来我国流动重力监测网络的发展、重力场时变在强震危险性判定中的作用以及重力监测仍需解决的问题。通过分析目前我国流动重力监测能力与预测研究的现状，探讨重力异常变化与地震预测三要素的特征指标，流动重力观测资料能较好地反映出地震孕育发生过程中的重力异常变化，尤其是6级以上的强震，并提出了我国流动重力监测预报发展战略之再思考。

GPS Velocity Field Clustering in the Sichuan-Yunnan Region

In this study, the hierarchical clustering method is adopted to classify GPS horizontal velocity field of the Sichuan-Yunnan region, then the F statistic test is employed to correct the misclassification of the GPS site in the geographical space. On this basis, taking account of the DB index and the irreversibility of the hierarchical clustering, the former classification is re-clustered. Finally, the Sichuan-Yunnan region is ultimately divided into six blocks: Tibet block (BYw), Aba block (BYe), Sichuan-Yunnan rhombic block (CD), south China block (SC), Tengchong-Baoshan block (DSw) and Indosinian block (DSe). Among them, the west and north boundaries of the CD block are the three-river fault area of “three-river parallel flow” and a velocity step line in the Batang region, respectively. Moreover, main Bayan Har fault divides the Bayan Har block (BY) into two blocks: BYw and BYe. The block division model of the Sichuan-Yunnan region is a reasonable scheme in mathematical sense, which is basically consistent with the results from geological data, can provide an explanation in another dimension for the division of the Sichuan-Yunnan region.