Source Volume Heterogeneity of the Ms = 6.6 Kaoiki l983 Earthquake: Precursors and Mainshock

最近我们发现的证据表明，考伊基地震每10.4年重复一次。位置和复发间隔似乎很稳定。然而，震级在5.5到6.6之间。我们建议研究上次（1983年11月）花木地震的前兆和主震源的非均质性，以便建立一个物理模型，对该地区下一次主震进行详细的预测。我们将在花木震源体内分析1979年至1983年的参数：(1)衰减（尾波衰减率），(2)b值，(3)局地地震的频率含量，(4)使用地震倍频的地震速度变化。我们对这一卷地震活动率的分析揭示了数据报告中最突出的前兆静息，其速率变化从震源附近的0%到震源以东的90%不等。初步结果表明，震源体积的这种非均质性也反映在尾波衰减率上：在本底地震活动率最高和前兆率下降最大的体积中，衰减更强。我们计划确定频率含量和b值是否也作为空间的函数而变化，以及这些空间差异如何与主震破裂的复杂性相关。

Recently we found evidence which suggests that the Kaoiki earthquake is repeated every 10.4 years. The location and recurrence interval appear to be very stable. However, the magnitude varies between 5.5 and 6.6. We propose to study precursors and mainshock source heterogeneities of the last (Nov. 1983) Kaoiki earthquake in order to develop a physical model which may allow a detailed prediction of the next mainshock in this area. The parameters which we will analyze for the years 1979 to 1983 within the Kaoiki source volume are: (1) attenuation (coda decay rate), (2) b-values, (3) the frequency content of local earthquakes, and (4) seismic velocity variations using earthquake doubles. Our analysis of the seismicity rate in this volume revealed the most outstanding precursory quiescence reported to data, with the rate change varying from 0% near the hypocenter to 90% east of it. Preliminary results suggest that this heterogeneity of the source volume is also reflected in the coda decay rate: Stronger attenuation is observed in the volume which contains the highest background seismicity rate as well as the greatest precursory rate decrease. We plan to determine whether frequency content and b values also vary as a function of space and how any of these spatial differences may relate to the complexities of the mainshock rupture.