jgg     2015 35 (5):  751-757    ISSN: 0412-1961  CN: 21-1139/TG Study of Small Earthquakes Activity Characteristics before  the Zigui 4.5, 4.7 Earthquake in 2014 1 Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA, 40 Hongshance Road, Wuhan 430071, China 2 Earthquake Administration of Hubei Province, 40 Hongshance Road, Wuhan 430071, China Received: 2015-01-06  Revised: null  Online: 2015-10-10 Supporting info