Preface to the Special Issue on Active Source Research

摘要

The seismic waveforms may present subtle changes related to the external loadings such as earthquakes(Pei Shunping et al.,2019)and landslides(Larose E.et al.,2015).Monitoring subtle changes provides a complementary tool for studying the dynamic processes(e.g.,Niu Fenglin et al.,2008),which has long been a major subject in seismology.The subsurface can be monitored by using natural repetitive events including repeated earthquakes(e.g.,Song Xiaodong et al.,1996)and ambient seismic noises(e.g.,Mao Shujuan et al.,2019).