关键词: 长白山, 火山, 谐频事件, 火山地震

Abstract: By analyzing seismic data recorded by temporary seismic network deployed at Changbaishan Tianchi volcanic region in the summers of 2002,2003 and 2005,we find one type of events whose spectra appear to be special.The station-averaged spectrum of each event consists of a series of evenly-spaced narrow peaks,the amplitudes of peaks change gradually with the frequency,the shape of spectrum is quite similar to harmonic signal in time domain.We called such event as harmonic-spectral event.During the three summers,38 harmonic-spectral events were detected,and most of them occurred in seismic swarms.Analyses show that the harmonic spectral characteristics of these events are most likely associated with seismic sources,which might be caused by interaction with crack walls and pressure disturbances within magmatic or hydrothermal fluids filled inside of cracks at special excitation conditions,during the rock rupture processes.We suggest that the apparent increasing of seismicity and emergence of harmonic events in Changbaishan Tianchi volcanic region are associated with deep magmatic intrusion activities.

Key words: Changbaishan, volcano, harmonic-spectral event, volcanic earthquake