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DoctorD DoctorD is offline
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First recorded activity by BoatBanter: Feb 2008
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Default Boothbay Me Unusual Tide Changes

On Nov 2, 9:49�pm, "Bill Kearney" wrote:
Good thought. Large meteorites aren't detectable by any means known to
modern man.


One large enough to cause that sort of wave action would undoubtedly be
detectable on earthquake gear.


This reminds me of an incident that happened in Chicago on June 26,
1954. Yes, Chicago. While the Second City will never have a tsunami
hit, Lake Michigan does occasionally have what is known as seiche. A
seiche is a sudden, large type of wave that can cause loss of life and
property damage.

On The Lake, a seiche is usually caused by air pressure and wind, such
as when a storm front moves quickly across its surface. Strong
downbursts can cause one large wave or a series of large waves. The
wave or waves then travel across The Lake until the seiche get to
shore. There it can rebond and travel to the opposite shore...a ping
pong effect.

The largest seiche on record to strike the Illinois coast of Lake
Michigan reached a maximum height of 10 feet, caused lakeshore damage,
and drowned eight people.

During the sailing season here in Illinois, April through October,
small seiches regularly strike the shores of Lake Michigan. These
typically range in size from a few inches to one foot. NOAA issues
warnings to Lake Michigan boaters when conditions favoring a seiche
are present. However, in 1954, when the record-high seiche occurred,
no such warning was issued. The entire Illinois coast experienced a
wave 2-4 feet high at 9:30am on that Saturday. But at the North Avenue
beach, down to Montrose Harbor, the wave grew to a maximum height of
10 feet. An undetermined number of fishermen and swimmers were swept
into the water by the surge. Most were rescued but eight drowned.

This particular seiche was caused by a very severe squall line that
crossed southern Lake Michigan a few hours earlier. It's thought that
the storm generated winds up to 60 miles per hour. This sent a seiche
toward Michigan City, Indiana. There a 6-foot wave reached shore at
about 8:10 a.m. and was rebounded across southern Lake Michigan
towards Chicago. A seiche moves much more slowly than a tsunami, which
can reach speeds of a hundred miles an hour. It took over an hour for
the seiche to travel the 40 miles from Michigan City to the Chicago
(approximately 30 mph).