1SURVEYOFGLOBESEISMICITYIN2007Atotalof22strongearthquakeswithM_S≥7.0occurredintheworldaccordingtotheChineseSeismicStationNetworkin2007(Table1).ThestrongestearthquakewastheSouthernSumatraearthquakewithM_S8.5onSeptember12(Fig.1).Earthquakefrequencyin2007washigherthanin2006,andenergyreleaseincreasedremarkablycomparedwiththatin2006.Therearethefollowingcharacteristics:
