烈度仪记录与强震及测震记录的对比分析——以2015年河北昌黎M_L4.5地震为例

Comparative analyses of records by seismic intensity instrument with strong ground motion records and seismograph stations records:Taking the M_L4.5 Changli earthquake of Hebei Province for an example

以2015年河北昌黎M_L4.5地震中测震、强震及烈度仪台站记录到的事件波形为研究对象,通过对比分析挑选的两组观测台站的记录波形以及不同台站的噪声记录特征,获得了烈度仪台站观测记录能力及特点的认识.结果表明:烈度仪台站产出的记录在部分频段(1—10Hz)与传统强震台站、测震台站均有较好的一致性,但在中长周期部分存在较大差异;在相同观测频带(0.1—10Hz)下,由烈度仪台站记录积分得到的速度时程、位移时程也与强震台站、测震台站的观测结果具有良好的相关性,说明烈度仪台站产出的加速度记录具有一定的可积分性;烈度仪台站记录的噪声水平远超出强震台站和测震台站,基本为仪器自噪声,不包含天然地脉动成分.此外,由于本研究所用的烈度仪采用了16位的A/D转换器,对震相到时的精确拾取产生了不利影响.综上,本文认为烈度仪台站较适用于中强地震的近场观测.

Based on seismic records of Changli ML4. 5 earthquake in Hebei Prov- ince, by analyzing two groups of waveforms and comparing seismic noise characteristics of seismograph station, strong ground motion station and seismic intensity instrument （SII） station, this paper acquires basic understanding of each kind of these stations, especially record micro-earthquakes. The results the SII station, such as the ability to show that, in certain frequency band （1-10 Hz）, seismic waveforms are quite similar for both the SII station and the strong ground motion station or the seismograph station, but large differences appear in mid-long period part. For the same frequency band （0.1-10 Hz band- pass filtered）, velocity history and displacement history that are integrated by the SII station data have good correlations and coherences with those from seis- mograph stations and strong ground motion stations, suggesting that the SII records have certain integrability to some extent. The noise levels of SII stations are far beyond seismograph stations and strong ground motion stations, normally are instrument noise without micro-tremor at all. As a result of only a 16 bit A/D convertor applied, the precision of sampled data is limited and then the accuracy of seismic phase picking will be adversely affected. In conclusion, we think that SII stations are more suitable for moderate to large near-field earthquakes monitoring.