地震工程学报2016，Vol.38Issue(1)：71-78,8.DOI:10.3969/j.issn.1000-0844.2016.01.0071
小地震与人工爆破记录的时频分析
Time-frequency Analysis of Records of Small Earthquakes and Explosions
摘要
Abstract
In this study,we developed a program to analyze the time-frequency spectrum of seis-mology events using MATLAB software.Among all the time-frequency analysis tools,we select-ed short-time Fourier transform (STFT)owing to its computational simplicity,adequate time and frequency resolution,and absence of undesirable cross terms.One disadvantage of STFT is the tradeoff between window length and time and frequency resolution.In order to determine the optimal window length,we wrote the code according to the sample rate of data records.We col-lected 82 broadband records,including data of 27 stations,of 5 natural earthquakes and 5 explo-sion events that occurred in the capital area between 2006 and 2008 having a magnitude in the range of 2.4 to 2.7.For the sake of convenience,we selected five pairs of events,each pair with one natural earthquake and one explosion event at similar epicenter distance,and analyzed the time-frequency spectrum.We plotted the time-frequency spectrum for each record with its origi-nal waveform and Fourier spectrum including the three components and their combination.Differ-ent time-frequency patterns exist for natural earthquakes and explosion events.In the first place, more peaks can be seen in the natural earthquake time-frequency spectrum,while the explosion e-vents spectrum has fewer peaks.In the second place,the peaks of natural earthquakes are located in a broad frequency band,whereas the peaks of explosion time-frequency spectrum are concen-trated in a narrow area.We analyzed all the data,not restricted to the five pairs of events,and the time-frequency spectrum pattern was found to be consistent.However,this pattern may be applicable only in the capital area because the explosion techniques are fairly complicated.The op-erator can use completely different explosion plans,and different local seismological wave propa-gation models produce diverse wave fields.When compared with Fourier analysis,the time-fre-quency spectrum,which is the time domain expansion of Fourier Spectrum,provides more infor-mation.关键词
时频分析/天然地震/人工爆破Key words
time-frequency analysis/natural earthquake/explosion分类
天文与地球科学引用本文复制引用
崔鑫,许力生,许忠淮,李铂,王峰..小地震与人工爆破记录的时频分析[J].地震工程学报,2016,38(1):71-78,8.基金项目
地球所核查项目(072403) （072403）
中国地震局三结合课题(161504) （161504）
