Fluctuations in long-term seismicity in response to changing water
levels along one of the Earth's largest lakes
Abstract
The Great Lakes region is usually considered to be seismically inactive.
However, earthquakes do occur around this region and may be related to
stress changes caused by water level fluctuations. We perform a
systematic template matching analysis of regional seismicity in
2013-2020 and calculate the Coulomb stress change caused by water
loading. The new catalog reveals 20-40 M>0 earthquakes/year
before 2019. The high seismicity rate in 2019 is dominated by active
aftershocks following the ML4.0 Ohio earthquake. Given
the limited number of earthquakes, neither seasonal pattern nor obvious
increasing trend of seismicity with fluctuating water levels can be
established. However, we cannot rule out the role of increasing water
level in reactivating the faults that host the 2019 Ohio earthquake
sequence. The lake loading induced stress change is found to increase
with water level at low effective friction coefficient, with maximum
positive stress change of ~0.2 KPa (µ = 0.2).