Ultralow frictional healing explains recurring slow slip events

• 成果类型: Article
• 署名作者: Shreedharan, Srisharan; Saffer, Demian; Wallace, Laura M.; Williams, Charles
• 署名单位: University of Texas System; University of Texas Austin; Utah System of Higher Education; Utah State University; University of Texas System; University of Texas Austin; GNS Science - New Zealand
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-14125
• DOI: 10.1126/science.adf4930
• 发表日期: 2023-02-17
• 页码: 712-717
• 关键词: san-andreas fault; laboratory observations; subduction interface; stress-drop; earthquakes; region; margin; trench

摘要

Plate motion on shallow subduction megathrusts is accommodated by a spectrum of tectonic slip modes. However, the frictional properties and conditions that sustain these diverse slip behaviors remain enigmatic. Frictional healing is one such property, which describes the degree of fault restrengthening between earthquakes. We show that the frictional healing rate of materials entrained along the megathrust at the northern Hikurangi margin, which hosts well-characterized recurring shallow slow slip events (SSEs), is nearly zero (<0.0001 per decade). These low healing rates provide a mechanism for the low stress drops (<50 kilopascals) and short recurrence times (1 to 2 years) characteristic of shallow SSEs at Hikurangi and other subduction margins. We suggest that near-zero frictional healing rates, associated with weak phyllosilicates that are common in subduction zones, may promote frequent, small-stress-drop, slow ruptures near the trench.