| This report lists the records of kinds low frequency events in foreign literatures including SSE (slow slip events), ETS events (episodic tremor and slip events), DLF events (deep low frequency events), VLF events (very low frequency events), LFE (low frequency earthquake), and the volcanic earthquake events, the glacier slow slip, etc. The paper main do analysis about below:low frequency events spectrum range, length of time, waveform characteristics qualitative. When compared all kinds of low frequency earthquake with its frequency range, frequency spectrum scope, duration, wave characteristic qualitative, we have got some new discovery. In addition, Wenchuan earthquake in Si-Chuan province near the fault of datum broadband network, using the literature corresponding frequency band pass filter of low events, detection to four similar low frequency incident waves. The paper got five conclusions:1) Low frequence events distributed in the global is widely and common, it not only happend in subduct-rushing fault plate areas. This paper analyzes the main record of stations in the global information, frequency range, sliding rate, low frequency characteristic frequency, events waveform features. Through analysis of the distribution in main plate of low frequency events, earthquakes and volcanoes and the recent large nature earthquake contrast, it found that the low frequency earthquake have a specific geographical distribution. Although all earthquake events is along the plate geographic scope, the low frequency event occurs mainly in30to40km specific depth, and particular location along the plates. Volcanical seismic is major into evenly distribute as pearl-like d along the plates. The nature earthquakes happened in natural plate, and more shallow depth (10to25km).2) As for division kinds of low frequency vibration events classification properties, the frequency-duration divided picture. It listed the major events analysis of low frequency areas recorded events, part of the volcanic earthquakes, natural earthquakes. It found that low frequency events have certain frequency range, and difference duration. It has a certain frequencies range and can distinguish the attributes of the main vibration events features from the frequency-duration divided picture. 3) Nearby Longmen mountains, just as the thrust-fault tectonic plate, is found to have low frequency events. The research results have showed that nearby the main fault do have low frequency events incidents. Through the corresponding filter detection, as well as low frequency wave characteristic analysis, we found there have four kinds of low frequency events before the wenchuan earthquake, all that is episodic tremor and slip events (ETS), deep low-frequency seismic events (LFE), deep low frequency events (DLF) and very low frequency events (VLF).4) The station records show that ETS events change fllowed by different time-period. There find to have the phenomenon of no record by nearby stations. The ETS event has different distribution stations records from that of normal earthquake. The record time indicate that, before wenchuan earthquake, the distribution stations of ETS events is changed by time and sliding migration..5) Trough clearly recorded stations preliminarily localization, it proofed, before wenchuan earthquake, the low frequency events is just similar happened near the fault of wenchuan earthquake. A larger numbers event is for ETS, company with VLF, and few DLF events.6) It is further analysis by the low frequency events as that of main recorded stations, events distribution, geological structure condition, sustainable research in the future. Low frequency events can be as larger supplement events for natural earthquakes, it can trigger mechanism and provide precursor to explore new directions for strong earthquakes. It can also provide new applications and the earthquake oretical diagram analysis for the broad band digital networks of china.
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