In June 2019, a magnitude 4.0 earthquake occurred beneath Lake Erie simply off the shoreline of Ohio, about 20 miles northeast of Cleveland.
Although no damages had been reported, the underwater quake was extensively felt as much as 60 miles away — all through northeastern Ohio and in components of Pennsylvania, Ontario and southeastern Michigan.
The quake and quite a few aftershocks occurred close to the tip of a interval of record-setting will increase in Nice Lakes water ranges and coincided with the best water stage ever recorded on Lake Erie. May there be a connection between Lake Erie seismicity and fluctuating water ranges within the lake?
To seek out out, College of Michigan researchers and their colleagues compiled a brand new catalog of 437 comparatively small Lake Erie-area earthquakes that occurred between 2013 and 2020 — probably the most full such catalog ever obtained. All the quakes had been smaller than the June 2019 occasion, and most had been possible not observed by residents of the area.
Then the researchers calculated the stresses that shifting Lake Erie water ranges would impart to faults within the rocks beneath the lake and used varied statistical strategies to search for a correlation between earthquake charges and water ranges.
“No conclusive correlation could possibly be established between earthquake charge and water stage or water-level change charge,” stated U-M geophysicist Yihe Huang, co-author of a examine revealed on-line Might 9 within the journal Seismological Analysis Letters.
The shortage of a smoking gun could also be partly because of the restricted variety of earthquakes within the new catalog, in response to the researchers. Additionally, Lake Erie-induced stress adjustments on close by earthquake faults are possible 10s or 100s of instances smaller than these seen in locations — such because the reservoir behind India’s large Koyna Dam — the place earthquakes have been blamed on altering water ranges.
“We can’t totally rule out the affect of accelerating water stage on reactivating the faults that hosted the 2019 Ohio earthquake sequence,” stated examine lead writer Dongdong Yao, a former U-M postdoctoral analysis fellow who’s now at China College of Geosciences.
“Our outcomes spotlight the need of denser and nearer monitoring of lake seismicity to additional examine the affect of fixing water loading on reactivating shallow faults on this area.”
To comply with up on their findings, Huang and her colleagues will use novel strategies to watch Nice Lakes regional seismology and can conduct physics-based simulations. Particularly:
- Huang and U-M seismologist Zack Spica are planning a area experiment this summer time to transform an present fiber-optic cable in Lake Ontario into sensors that may higher monitor seismicity and different phenomena reminiscent of seiches, backside currents or water-level adjustments. Earlier research in different components of the nation have demonstrated the potential for utilizing present networks of fiber-optic cables — the identical optical fibers that ship high-speed web and HD video to our houses — to review earthquakes.
- Huang and colleagues will simulate the extra stresses on Lake Erie-area earthquake faults attributable to excessive water ranges, in addition to the diploma to which lake water percolating into the bedrock might assist lubricate these faults. “These two results could also be competing with one another in nature, and the physics-based simulations might help us decide which impact is extra essential,” she stated.
As well as, Huang and her crew are nonetheless analyzing knowledge from a community of eight seismometers, generally known as the LEEP challenge for Lake Erie Earthquake exPeriment, that they operated within the western nook of Lake Erie from October 2018 to July 2021.
The Nice Lakes area is usually thought of to be seismically inactive, and earthquakes of magnitude 5 or larger are uncommon. Nonetheless, earthquakes with magnitudes larger than 2 happen two or 3 times a yr within the area, primarily round lakes Erie and Ontario. Earthquakes with magnitudes of two.5 to three are the smallest typically felt by folks.
“We aren’t sure whether or not Lake Erie-area faults can produce damaging or lethal earthquakes,” stated Huang, assistant professor within the U-M Division of Earth and Environmental Sciences. “That is why seismologists are keen on finding out a magnitude 4-type earthquake sequence from this area.”
Because the early 2010s, japanese Ohio has seen a big improve within the frequency of comparatively small earthquakes. The origins of these earthquakes are poorly understood, however some earlier research recommended they are often attributed to wastewater injection and hydraulic fracturing actions.
Injection-induced seismicity has additionally been recommended because the set off for the area’s final magnitude 5 earthquake, which occurred in January 1986 in northeastern Ohio, east of Cleveland in southern Lake County.
Within the new examine, which covers the interval from 2013 to 2020, the U-M-led crew discovered a cluster of earthquakes within the neighborhood of the 1986 temblor and close to wastewater disposal wells that had been working through the examine interval. They concluded that this cluster of quakes “is likely to be probably induced by wastewater disposal.”
“Extra intriguingly, the 1986 earthquake was additionally taking place throughout one other interval of recorded high-water ranges throughout the Nice Lakes,” the authors wrote. “Nonetheless, as a result of a big distance relative to Lake Erie, it could be troublesome to judge the affect of lake-induced stress change on triggering the 1986 earthquake.”
To create their new catalog of 437 Lake Erie-area quakes, the researchers began with 27 beforehand reported earthquakes listed within the Superior Nationwide Seismic System Complete Earthquake Catalog, which is called the ComCat catalog.
U.S. seismometer networks captured steady recordings of floor motions within the area through the examine interval. Utilizing the waveforms produced by the 27 identified earthquakes as templates, the crew scanned the continual recordings looking for beforehand undetected earthquakes with related waveforms. The method is known as template matching.
Many of the earthquakes within the new catalog wouldn’t have been felt by space residents and are solely detectable by close by seismometers delicate to tiny quantities of floor shaking.
The brand new catalog revealed 20 to 40 small earthquakes per yr through the examine interval, main as much as the June 2019 occasion. A excessive seismicity charge in 2019 was dominated by aftershocks following the magnitude 4.0 earthquake.
Along with compiling the excellent new catalog, the crew was additionally first to map the fault that ruptured to provide the 2019 quake, which occurred at a depth of roughly 2 kilometers (1.2 miles).
Along with Yao and Huang, the authors of the Seismological Analysis Letters paper are Liang Xue of Bowling Inexperienced State College and Syracuse College, Yuning Fu of Bowling Inexperienced State College, Andrew Gronewold of the College of Michigan Division of Earth and Environmental Sciences and the Faculty for Setting and Sustainability, and Jeffrey Fox of the Ohio Division of Pure Assets. Funding to Yao and Huang was offered by the College of Michigan.