Abstract: Earthquake is a form of tectonic activity, an earthquake contains a lot of information, its frequency range is very wide. So far, the main frequency range of seismic records is below 100Hz, and the ultrahigh frequency seismic information got less attention by researchers. However, high frequency microseismicity can provide important information on micro-activities of fault. This paper introduces a new 100kHz ultrahigh frequency seismometer and its first application on high frequency microseismicity observation. The telemeter has been applied in Dali, Yunnan. Several high frequency microearthquakes were recorded and the corresponding earthquake location and spectral analysis were done. The results show that high frequency microearthquakes caused by crustal movement do exist and can be recorded by our telemeter. The recorded microearthquakes are of magnitudes between M_W=-3.0 and M_W=-1.0, maximum hypocentral distance up to 4.87km, dominant frequency ranging from 100Hz to 300Hz, and maximum frequency as high as 800Hz. It is possible that the ultrahigh frequency microseismicity observation(UFMO) will become a new approach to the study on the tectonic movement.

Key words: high frequency microseismicity, ultrahigh frequency seismometer, corresponding earthquake location, spectral analysis

摘要： 一次地震包含很多信息，其频率范围很宽。迄今为止，地震记录观测的主要频率范围在100Hz以下，超高频地震信息少为研究者所关注。然而，高频微震活动却是反映断层微动态过程的重要信息。文中介绍了新研发的100kHz超高频地震仪，并对该仪器在云南大理地区观测所记录到的地震信号进行了震源及信号频谱特征等方面的分析。结果表明，地壳运动产生的高频微震信号真实存在并且可以被仪器所记录。这次观测每天记录到上百次-3～-1级的微地震信号，最大震源距为4.87km。信号的主频带范围为100～300Hz，还包含了达800Hz的高频信号成分。超高频微震观测有可能成为研究小区域构造活动的一个新的途径。

关键词: 高频微震活动, 超高频地震仪, 震源, 频谱特征