地震研究

研究了东南沿海地震带20世纪第Ⅳ活跃幕的两个特征,包括该带中强地震与阳江地震窗的对应关系以及该带M_L4地震长时间平静的震兆意义。结果表明:在第Ⅳ活跃幕中,阳江地区M_L3地震(去余震)的活跃不仅与本区5级左右地震活动有关,还与东南沿海地震带5级以上强震活动有关,震前阳江地区M_L3地震滑动3月频次出现升高现象,阳江地区M_L3地震活动可作为东南沿海地震带的地震“窗口”; 在东南沿海地震带活跃幕期间,M_L4地震发震间隔△T≥300 d具有震兆意义,是5级地震的短期或中短期指标,而在平静幕期间,M_L4地震的长时间平静并不具备震兆意义,只是区域应力场处于松弛状态下的正常表现。

We studied the two characteristics of the Ⅳ active episodes in seismic belt of Southeast China coast in 20th century. The one is the corresponding relation between the southeast coastal seismic belt and the Yangjiang seismic window,the other one is the seismic precursory significance about M_L4 earthquakes which wasn't occurred for a long time. The results showed that the active of M_L3 earthquakes in Yangjiang were affected not only by M5 earthquakes occurred in Yangjiang,but also by M>5 moderate-strong earthquakes occurred in seismic belt of Southeast China coast in Ⅳ active episodes. Before the moderate-strong earthquakes,occurrence frequency of M_L3 earthquakes in the slip with every 3 months in Yangjiang raised,so M_L3 earthquakes in Yangjing can be as the seismic window in seismic belt of Southeast China coast. In active episodes of seismic belt of Southeast China coast,the occurrence time interval △T≥300 d of M_L4 earthquake was the index of M5 earthquake in short-term or medium-short term prediction. However,M_L4 earthquakes weren't occurred for a long time,which were normal appearances of the regional stress field in relaxed state.However it wasn't the seismic precursory significance in quiet episodes.

引言
1 东南沿海地震带的范围
2 阳江地震窗口与东南沿海地震带中强震的对应关系
3 东南沿海地震带M_L≥4地震异常平静的震兆意义
4 结论

图1 东南沿海地震带范围及1970年至今ML≥5<br/>地震空间分布(虚线框为东南沿海地震带范围,<br/>星号为阳江地震窗所在位置)<br/>Fig.1 Scope of seismic belt in Southeast China Coast and spatial distribution of ML≥5 earthquakes from 1970(broken line means the scope of seismic belt in Southeast China Coast,star means the location of Yangjiang seismic window)

图1 东南沿海地震带范围及1970年至今ML≥5
地震空间分布(虚线框为东南沿海地震带范围,
星号为阳江地震窗所在位置)
Fig.1 Scope of seismic belt in Southeast China Coast and spatial distribution of ML≥5 earthquakes from 1970(broken line means the scope of seismic belt in Southeast China Coast,star means the location of Yangjiang seismic window)

图2 东南沿海地震带M≥5地震M-t图(1900年至今)<br/>Fig.2 M-t chart of M≥5 earthquakes in seismic belt of Southeast China Coast from since 1900

图2 东南沿海地震带M≥5地震M-t图(1900年至今)
Fig.2 M-t chart of M≥5 earthquakes in seismic belt of Southeast China Coast from since 1900

图3 东南沿海地震带M-t图(ML≥5)及阳江<br/>ML≥3地震滑动3月频次(1980-01～2012-02)<br/>Fig.3 M-t chart of ML≥5 earthquakes in seismic belt of Southeast China Coast and slip 3 months frequency of Yangjiang ML≥3 earthquakes (1980-01～2012-02)

图3 东南沿海地震带M-t图(ML≥5)及阳江
ML≥3地震滑动3月频次(1980-01～2012-02)
Fig.3 M-t chart of ML≥5 earthquakes in seismic belt of Southeast China Coast and slip 3 months frequency of Yangjiang ML≥3 earthquakes (1980-01～2012-02)