Development and application of data assimilation methods for GPSdata to estimate frictional properties on plate boundary faults

板块边界断层滑动的时空变化主要受断层上的摩擦性质控制。为了估计断层上的摩擦性质，我们发展了利用GPS数据估计断层摩擦定律中的参数(摩擦参数)的数据同化方法。我们将该方法应用于2011年东北9.0级地震后的余滑区，以估计余滑区的摩擦性质。结果表明，摩擦参数依赖于滑移率，且滑移率越高，摩擦性能越不稳定。

Spatial and temporal variations in slip on plate boundary faults is primarily governed by frictional properties on faults. To estimate frictional properties on faults, we develop data assimilation methods to estimate parameters in fault friction laws (friction parameters) using GPS data. We apply this method to afterslip following the 2011 Mw 9.0 Tohoku-oki earthquake to estimate frictional properties in the afterslip area. The results show that the friction parameter, which has been estimated to be constant in previous studies, is dependent on slip rate and higher slip rates result in less stable frictional properties.