Seismically-induced quartz grain alterations as indicators of past earthquake events

Seismic activity often triggers liquefaction, a process where water-saturated sediments lose their strength due to an increase in pore water pressure. This process leads to the development of soft-sediment deformation structures (SSDS), such as load casts, clastic dykes, flame structures etc. However, distinguishing seismogenic SSDS from those triggered by other mechanisms (e.g., storms, overloading) can be challenging.

This study investigates the micromorphological changes in quartz grains derived from SSDS caused by liquefaction triggered by seismic shocks., Laboratory simulations mimicking seismic conditions revealed characteristic quartz alterations, including microcracks, edge corrosion, and grain fragmentation. These features were found to be closely linked to the duration of seismic exposure.

Particularly notable was the discovery of gold within quartz cracks, which serve as direct evidence of seismic events and underscore the role of seismicity in mineral redistribution. This novel finding highlights the potential of quartz grains as micro-scale markers for reconstructing past seismic activities. Geochemical factors, such as pH and redox potential, further influenced the behavior of liquefied sediments and the extent of quartz grain deformation, demonstrating the complex interplay between seismic forces and geochemical conditions in shaping sedimentary records.