Is there accelerated crustal deformation before large earthquakes? A case study of strong intra-plate earthquakes in China

The existence of a detectable precursory phase of fault slip preceding major earthquakes has been a subject of ongoing debate for decades. A recent study (Bletery and Nocquet, 2023) demonstrated exponential acceleration of fault slip prior to large earthquakes. Conversely, (Hirose et al., 2024) reported no such phenomenon when analyzing tiltmeter data. Furthermore, their analysis focused predominantly on subduction zone earthquakes, with limited consideration of intraplate earthquake scenarios. In this study, we examined 15 M ≥6.5 intraplate earthquakes in China from 2010 to 2024 and found no clear evidence of deformation acceleration prior to these events. We also investigated several key factors contributing to uncertainties in this approach. Our findings suggest that the exponential acceleration phenomenon is associated with specific earthquake characteristics and is influenced by the spatial distribution of proximal seismic signals.