摘要:
北纬31°-35°、东经119°-125°范围内的南黄海地震区,中强地震活动频繁,这主要是由一组北北东向和北西-北西西向共轭走滑活动断层及张性铲形活动断层引起的,该区内的中强震活动具有准周期性,震中呈东移趋势,区内地震在原地或同一构造部位重复发生的概率比较高,且空间分布是不均匀的,其中,海域地震强度明显高于陆域地震,在第Ⅲ、Ⅳ地震活跃期内,中强震主要发生在北纬33°±1°、东经121°±1°所在的南黄海海域的南部盆地,本区第Ⅳ活跃期内中强地震的活动水平与近期内中小地震的活动水平相当,同时,海域地震还具有成丛性及57 年、6 年的节律,地震震中具有南北迁移的特征。
Abstract:
South-yellow-sea seismic area(31°-37°N、119°-125°E) is a seismically active area for moderately strong earthquakes.The moderately strong seismic activity is due to the movement of a group of NNE and NW-NWW conjugate strike-slip fault and tensional shovel-like fault, and shows a quasi-periodicity.The epicenter takes on eastward migratory trend.Earthquake occurs at in-situor in common structure part in higher probability, its spatial distribution is heterogeneous, and its strength is greater in sea area than in land area.During the Ⅲ、Ⅳ seismically active period, moderately strong earthquakes occured in the south-pan(33°±1°、121°±1°) of south-yellow-sea mainly, which in the sea area possesses swarm and rhythm of 57-year and 6-year, and its epicenter migrates from south to north each either.The degree of seismicity of moderate earthquakes during Ⅳ seismically active period corresponds to that of small-moderate earthquakes of late years.
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