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ISSN 2096-7780 CN 10-1665/P

皖东地区定点形变观测同震响应分析

Analysis of coseismic response of fixed-point deformation observation in eastern Anhui

  • 摘要: 皖东地区位于郯庐断裂带中南段,2022年建成涵盖体应变与地倾斜的定点形变观测台网。各形变观测仪对于远大震同震响应较好,表现形式为长周期振荡衰减型同震形变波;对于近震及地方震,震时主要表现为脉冲、阶跃或掉格。选取2023年12个地震事件,分析不同仪器同震响应特征及其与震级、震中距的相关性,结合傅里叶变换开展频谱分析,对比仪器映震效能。结果显示:在捕捉地震信号上钻孔倾斜仪优于钻孔体应变仪,秒采样的CBT钻孔倾斜仪效果最优;地震响应延迟随震中距增大非线性增加、随震级增大趋于稳定,同震持续时间与震中距、震级呈正相关;CBT钻孔倾斜仪频带宽度与主频略逊于宽频带地震计,两分量响应能力相当,频谱差异是仪器物理结构、核心性能与地质环境协同作用的结果。

     

    Abstract: The eastern Anhui region is located in the central southern section of the Tan Lu fault zone, and a fixed-point deformation observation network covering body strain and ground tilt will be established in 2022. Each deformation observation instrument has a good response to large earthquakes, manifested as long-period oscillation attenuation type coseismic deformation waves; For near earthquakes and local earthquakes, the main manifestations during the earthquake are pulses, steps, or grid drops.Based on 12 seismic events that occurred in 2023, the cosismic response characteristics of different instruments were analyzed, along with their correlations with earthquake magnitude and epicentral distance. Spectral analysis was conducted using the Fourier transform, and the earthquake detection capabilities of the instruments were compared. The results indicate that borehole tiltmeters are superior to borehole volumetric strainmeters in capturing seismic signals, with the second-sampled CBT borehole tiltmeter exhibiting the best performance. The seismic response delay increases nonlinearly with increasing epicentral distance and tends to stabilize with increasing magnitude. The cosismic duration is positively correlated with both epicentral distance and magnitude. The frequency band width and main frequency of CBT borehole inclinometer are slightly inferior to broadband seismometers, and the response ability of the two components is equivalent. The spectral difference is the result of the synergistic effect of the physical structure, core performance, and geological environment of the instrument.

     

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