jgg     2011 31 (增1):  38-42    ISSN: 0412-1961  CN: 21-1139/TG PRELIMINARY ANALYSIS OF CHARACTERISTICS OF ANOMALOUS VARIATION OF GEOELECTRIC FIELD BEFORE YUSHU Ms7.1 EARTHQUAKE Zhang Xiaotao 1) ;Chen Huaran 2) ; Ma Xinxin 2) ; Liu Xiaocan 2) ; Yao Li 2) ; and Yuan Yahong 2) 1)Central Seismostation of Handan , Handan 0560012)Institute of Geophysics，China Earthquake Administration，Beijing 100081 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null