Ambient Noise Analysis by the Technology of PSD and PDF in Hotan

Session: Alpine-Himalayan Alpide Shallow Earthquakes and the Current and the Future Hazard Assessments [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Hotan Array is the first small-aperture array in China that has been independently built and operated till now. It is responsible for monitoring the nuclear test in India and Pakistan and the earthquake activity in western China. The waveform data of the array is full of ambient noise, which directly affects the data quality. In order to evaluate the noise level of the array, the Welch average period method is utilized to estimate the power spectrum of hundreds of thousands of noise samples recorded by 9 sub-stations in this paper, so as to summarize the spectrum anomalies. On this basis, the probability density function graph and the single-frequency curve are plotted to study the variation range and law of ambient noise, so as to finally put forward constructive opinions on the noise reduction of the array. The research results show that the long-period noise power spectral density of the central station varies significantly with the seasons, characterized by periodicity. Due to the influence of temperature and pressure, the horizontal component long-period noise changes greatly and the local frequency band exceeds the NHNM in winter. It is recommended to improve the instrument installation conditions or use mathematical methods to correct. The short-period noise variation of all sub-stations is opposite to that of the long-period. Affected by the quarry, the spectral density curve shows a regular high-frequency tip between 4-8Hz. The A1, B3 and B4 sub-stations are the most obvious, able to pass narrow-band filtering or bunching to suppress. The research results obtained in this paper provide an important basis for the operation and maintenance of array. In addition, the different seismic spectrum features summarized are important references for seismic interpretation.

Presenting Author: Qianli Yang

Authors