论文标题
南部卡斯卡迪亚的8年的低频地震目录
An 8-year-long low-frequency earthquake catalog for Southern Cascadia
论文作者
论文摘要
低频地震（LFE）是小地震，典型的幅度小于2，相对于普通的小地震，频率大于10 Hz的幅度降低。它们的发生通常与俯冲带沿板边界沿板边界的构造震颤有关，偶尔会改变断层区。它们通常分为家庭，给定家族的所有地震源自板界面上的同一个小斑块，并以爆发的方式或多或少地反复出现。在这项研究中，我们扩展了Plourde等人获得的LFE目录。 （2015年）在2008年4月至2004 - 2011年8年期间震颤活动的一集中。 Boyarko等人的所有震颤。 （2015）北部42度以南的目录具有LFE活动，但我们已经确定了几个较小的LFE发作，而没有相关的震颤活动，并将其目录向前和向后扩展大约3年。与卡斯卡迪亚北部一样，下dip lfe家族的复发间隔比上浸家庭小几倍。在2008年4月的情节震颤和滑动事件中，最佳记录的LFE家族在每个LFE家族的破裂前后1.5天开始表现出强烈的潮汐库仑压力敏感性。最南端的LFE家族被解释为在俯冲板边界上，在震颤的上倾角附近，其复发时间很短。同样，这些LFE倾向于在预测的潮汐库仑应力阻止板边界上的滑动时发生。两种观察结果都表明，这个LFE家族可能处于不同的错误。
Low-frequency earthquakes (LFEs) are small magnitude earthquakes, with typical magnitude less than 2, and reduced amplitudes at frequencies greater than 10 Hz relative to ordinary small earthquakes. Their occurrence is often associated with tectonic tremor and slow-slip events along the plate boundary in subduction zones and occasionally transform fault zones. They are usually grouped into families, with all the earthquakes of a given family originating from the same small patch on the plate interface and recurring more or less episodically in a bursty manner. In this study, we extend the LFE catalog obtained by Plourde et al. (2015) during an episode of high tremor activity in April 2008, to the 8-year period 2004-2011. All of the tremor in the Boyarko et al. (2015) catalog south of 42 degrees North has associated LFE activity, but we have identified several smaller episodes of LFEs without associated tremor activity, and extend their catalog forward and backward by a total of about 3 years. As in northern Cascadia, the down-dip LFE families have recurrence intervals several times smaller than the up-dip families. For the April 2008 Episodic Tremor and Slip event, the best recorded LFE families exhibit a strong tidal Coulomb stress sensitivity starting 1.5 days after the rupture front passes by each LFE family. The southernmost LFE family, which has been interpreted to be on the subduction plate boundary, near the up-dip limit of tremor, has a very short recurrence time. Also, these LFEs tend to occur during times when predicted tidal Coulomb stress is discouraging slip on the plate boundary. Both observations suggest this LFE family may be on a different fault.
