Seismogram of the June 10, 2019, magnitude 4.0 Lake Erie earthquake, recorded at the University of Michigan seismic station in Ann Arbor. Image credit: University of Michigan
In June 2019, a magnitude 4.0 earthquake occurred beneath Lake Erie just off the shoreline of Ohio, about 20 miles northeast of Cleveland.
Though no damages were reported, the underwater quake was widely felt up to 60 miles away-throughout northeastern Ohio and in parts of Pennsylvania, Ontario and southeastern Michigan.
The quake and numerous aftershocks occurred near the end of a period of record-setting increases in Great Lakes water levels and coincided with the highest water level ever recorded on Lake Erie. Could there be a connection between Lake Erie seismicity and fluctuating water levels in the lake?
To find out, University of Michigan researchers and their colleagues compiled a new catalog of 437 relatively small Lake Erie-area earthquakes that occurred between 2013 and 2020-the most complete such catalog ever obtained. All of the quakes were smaller than the June 2019 event, and most were likely not noticed by residents of the region.
Then the researchers calculated the stresses that shifting Lake Erie water levels would impart to faults in the rocks beneath the lake and used various statistical methods to look for a correlation between earthquake rates and water levels.
Their verdict?
"No conclusive correlation could be established between earthquake rate and water level or water-level change rate," said U-M geophysicist Yihe Huang, co-author of a study published online May 9 in the journal Seismological Research Letters.
The lack of a smoking gun may be partly due to the limited number of earthquakes in the new catalog, according to the researchers. Also, Lake Erie-induced stress changes on nearby earthquake faults are likely 10s or 100s of times smaller than those seen in places-such as the reservoir behind India's massive Koyna Dam-where earthquakes have been blamed on changing water levels.
"We cannot fully rule out the impact of increasing water level on reactivating the faults that hosted the 2019 Ohio earthquake sequence," said study lead author Dongdong Yao, a former U-M postdoctoral research fellow who is now at China University of Geosciences.
"Our results highlight the necessity of denser and closer monitoring of lake seismicity to further investigate the impact of changing water loading on reactivating shallow faults in this region."
