用于地震观测的瞬态滤波试验数据分析

The analysis on test data of instantaneous filter used for earthquake observation

地震数据采集器中的滤波技术是影响地震观测数据质量的重要因素。本研究通过实测数据对比分析了最小相位滤波、线性相位滤波和瞬态滤波对观测数据的影响程度。实测波形数据证实了理论分析的预期,最小相位滤波在观测地方性微小地震时,初动半周期及后续波的失真均较大,利用波形作深入研究时,应注意该失真的影响;线性相位滤波引起的"前缀"可能会干扰震相的正确判读,不宜用于以震相分析为主要用途的地方震观测;瞬态滤波兼有前两类滤波的优点而无其缺点,是观测地方震和水库地震的优良滤波技术,但应用瞬态滤波必须提高采样率。

The data filter used in earthquake data acquisition instrument is an important factor that influences the quality of the recorded data. Three kinds of filter methods, minimum phase filter, linear phase filter and instantaneous filter, are applied to the earthquake data acquisition instruments. Then the impacts to the recorded data are calculated and compared, some conclusions are induced. Firstly, distortion of half period of first P arrivals and follow-up wave is large when minimum phase is used for observing local earthquake. Therefore, it needs to pay attention to the distortion when deeply studying the earthquake wave. Second- ly, prefix wave caused by linear phase filter maybe interfere with the phase interpretation of seismic waves, so it is not suitable for observing local earthquakes. Thirdly, instantaneous filter has the merits of minimum and linear filters and avoids the above demerits. Instantaneous filter is considered suitable for observing local earthquake and reservoir earthquake. However, it is at the cost of increasing sampling rate using instantaneous filter.