Great Lakes Tsunamis?

E

El and Bill

New member
Don't want C-Dory boaters living and boating along the shores of the Great Lakes to feel 'left out' by the tsunami discussions among coastal boaters. Did you know there are wave threats in the Great Lakes (not just from storm waves) as well? On the lakes, the threat is not specifically from tsunamis but from SEICHES.

In simple terms, what is a seiche? First - pronounced sigh-shhh, and first used by a Swiss geologist to describe wave oscillations in their lakes.

We have all created a seiche - remember when you were a kid taking a bath and you discovered sloshing rhythmically back and forth caused a big wave to slursh over the end of the tub? Just get the right resonance and you can make a big wave. A resonant oscillation in an enclosed body of water is a seiche.

Earthquakes can cause a swimming pool seiche. California's Northridge quake in 1994 caused our backyard swimming pool in Nevada to slosh back and forth, slopping water out the ends.

A large earthquake can cause seiches in any enclosed body of water - the Great Lakes or any lake.

In 1954, a maximum 10-foot high seiche struck the eastern shore of Lake Michigan- drowning eight people, and creating havoc in harbors. This seiche was storm-caused.

http://www.isgs.illinois.edu/sections/e ... ches.shtml

Every year seiches are recorded in the Great Lakes (shallow Lake Erie, due to it's orientation parallel with weather systems, often has seiches).

So, when you fish, travel, or live on or near water it is good to know the potential (but not everyday) hazards.
 
Bill,

I think that I have read accounts of some segments of the Mississippi running backwards when the New Madrid quakes of 1811-12 hit. Aren't there still oxbow lakes that were formed when the river cut off some of the meanders durning that event?
 
We have a Cottage on Lake Michigan - Bay of Green Bay. Once every couple years the wind we'll hit just the right direction and push all the water down the bay. When this happens our water level/wave heights will increase around the 10 feet mark. We have a very heavy rough water pier that was anchored in and 4 ft off the water and it was knocked out of the water. We also had our Boston Whaler on a lift 5 ft off the water and it was knocked off the lift and destroyed. This is not really caused by the waves but more the water levels rising so fast.

Our Cottage has a natural sea wall cliff, so no worries hitting the Cottage. Older folks around us laugh that all the young folks put out piers and the old folks know better. But we have 80 degree water in the bay by us, so we'll take our chances.
 
While driving the cruise boat on Jackson Lake, there were two occasions where we saw waves in the lake when there was no wind and not wake from a boat. On both occasions, these were very close to the Teton fault, easy to pick out on the lake with the depth sounder (about 450 feet). The area is definitely seismically active - we felt several tremors while on land.

Do those have a name?
 
The Mississippi sure did run backwards after the New Madrid quake - that was a huge quake, and the rift is still seismically active today. There are lakes (one is named Quake Lake) where oxbows were cut off by the shifts in topography. We have anchored in one when coming down that part of the river on Halcyon.

Church bells rang in Boston from the passage of the seismic waves from that quake. If quake that happened today, the destruction in the Midwest would be horrific.
 
Although Lake Erie (where I have sailed/boated for forty years) is the smallest of the Great Lakes it has close to 10,000 square miles, with an average depth of only 62 feet. The average depth in the western basin, where we dock and where the destination/tourist islands are located is only 35 feet.

As a result, when we have heavy west winds over a number of days I have seen several feet of water blown toward the eastern end of the lake. In fact, in '83 I drove to my marina to check on my 18 foot sailboat after four days of heavy weather to find my boat hanging from its dock lines, due to the water being blown east!

Also, in the 1980's I was reading a copy of American History Illustrated and they always had the last page devoted to the history of 25 to 100 years ago. There was an account of a "tsunami" heading south across the lake from Canada and Cleveland being hit by a fifteen foot wall of water! I traveled to Cleveland and spent a few days in the Cleveland Library's microfiche archives reading local papers to find accounts of the event. It seems that the wave, if I remember correctly, came three blocks into the city, knocked trolleys off their tracks and took a number of lives.
I also discovered that there have been other more minor events, but nothing like the "big one".

There is a lot of interesting marine history out there.

Thanks for bringing this up, El and Bill. Have a great trip in Europe. Marcia and I will be thinking of you.

Regards,

Nick
" Valkyrie"
 
For a brief time, Rochester had a "big ferry" that ran back and forth to Toronto a couple of times per day during the summer months. It created a powerful wake: the first two were huge (tsunami-like) and arrived onshore "silently," without warning.

We have a cottage at a campground on L. Ontario, halfway between Rochester and Buffalo. One afternoon, while out for a sail in my Sunfish, I saw the ferry go by, ca. 10 miles away in the middle of the lake, and felt the wake pass under my boat.

When I returned to shore, my trailer dolly, which I had pulled up above the waterline but left on the beach, was nowhere to be found. Gradually, it dawned on me that it had been washed "out to sea" when the wake from the "big ferry" washed up onshore. (We found it a year later, when it washed back up on shore about a mile away from our campground!)
 
Bill – My family has lived on the shore of Lake Michigan north of Chicago since 1958, and one time in about 1965 there was an event that was called a seiche which had no resemblance to the description discussed on the ISGS site. It occurred on a completely normal, sunny day and the lake was calm. What happened was the water line retreated from the shore about 100 yards and stayed that way for a few hours. So the sandy bottom was exposed, much to our amazement, and it stayed that way for perhaps 3 hours. Then the water rather suddenly flowed back in somewhat like an advancing tide but much faster. Have you, or has anyone else, heard of such a thing? It does not fit the characteristics of a classic seiche, which we thought it was.
 
The med also has seiches. We just missed one at Ciutadella Harbor, Menorca Island (Balaeric Islands of Spain). Locally these are called "Rissaga" We had anchored in Mahon, a few days before Cuitadella Harbor had a catestrophic seiche and destroyed all of the boats in that harbor on the other side of the Island. My understanding is that these are meteorological tsunamis--due to barametric pressure changes in resonate systems, and certain harbors are subject to this--others are not.
 
Jay - the event you witnessed in Lake Michigan may have been related to earthquakes in Alaska (the big one in '64 but another in '65) and been seismic seiches in the lake or perhaps it was meteorological - depending on the period of 'sloshing,' all the water could be on the Michigan side, drying up the Illinois side, and then slosh back to Illinois - or, if the oscillation is just right, the node of water could 'heap' up in the middle of the lake, drying both shores, then slosh back to lower the middle and heap up on the shores. These are only possibilities, but might explain the event you saw.
 
Question for El and Bill. Why couldn't one of the Great Lakes have a tsunami if a quake happened beneath the lake?
So maybe there are no faults beneath any of the lakes so no tsunamis?

Jay
 
El & Bill,
Our late friend Leo, who had 50 years of experience boating on Lake Superior, was tied up at CPR Slip on St. Ignace Island once and was awakened from a sound sleep when his coffee cup slid off the table. Upon investigation he found that a seiche had left his sailboat sitting on the bottom! He told us, "If I hadn't seen it, I wouldn't have believed it." Apparently CPR is fairly prone to the affects of a seiche, perhaps due to its Cape Cod - type configuration.
Al
 
I saw one of those on a pond I was working on in the 90's out east of Redmond Washington. When you had the earthquake about a 2 footer rolled across that pond. The only reason I knew there was a quake was because the trees started to sway as the wave came across the pond. Didn't realize they had a name for them.
 
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