资源环境科技发展态势分析平台

Tectonic tremor and low-frequency earthquakes (LFE) have been identified globally, but the physical mechanisms responsible for different types of LFE recurrence patterns are still elusive. Here we use a brittle ductile friction model to study the frictional conditions leading to different LFE recurrence patterns observed in central California. We do a comprehensive search of the friction parameters, including the brittle contact failure length and ductile damping strength to generate synthetic LFE bursts that match three different occurrence patterns of LFE bursts. We find that the output synthetic LFE burst recurrence type varies under different frictional conditions. The chaotic recurrence LFE sources require a higher brittle-to-ductile friction ratio, consistent with the observation that they are mainly at shallower part of the brittle-ductile transition zone. The trimodal recurrence LFE sources require a wide distribution of asperity sizes, indicating that the segment of deep San Andreas Fault between Monarch Peak and Parkfield is likely to be more fragmented and weaker than the surrounding segments.