On Aug 17, 3:34 pm, rick++ wrote:
Searching the NEIC online catalog returns 34 M8+s in the past 35
years.
There was one year with four (2000) and three others with three and
nine
years with none.

I go by a loose "Law of Three" in characterizing earthquake size-
frequency;
That is given a mean recurrence interval of "N" years, its not
uncommon
to see gaps of 1/3 N to 3N. I've seen this in San Andreas
paleoseismics too.
I suspect this has something to do with the quasi-fractal nature of
seismicity
statistics in time, space, and size. But I'm not sure how to prove
this.

Link them to severe weather events for a start. For instance, from a
link supplied in another thread he

This is when the fat lady sang:

1927 05 22 - Tsinghai, China - M 7.9 Fatalities 200,000

"The flooding was a result of persistent heavy rains that fell across
the central U.S. starting in
August 1926 and continuing through the spring of 1927.

August to December 1926

Around the middle of August 1926, the rains began to fall over the
upper midwestern U.S. The first storm system lasted for many days,
starting in South Dakota, Nebraska, Kansas, and Oklahoma and moving
eastward into Iowa, Missouri, Illinois, Indiana, Kentucky, and Ohio.

This system was followed within two days by a second and third storm,
which moved across the Mississippi Valley, causing rain to pour for
two weeks.

By September 1, 1926, dozens of streams and rivers began to overflow
their banks and inundate towns from "Carroll, Iowa to Peoria,
Illinois, 350 miles apart". The deluge continued through September
into early October and caused the Mississippi River to rise rapidly,
washing out bridges and railroads. For example, 15 inches of rain fell
over the course of three days in Iowa, flooding Sioux City.

By the end of October 1926, when the rains stopped, flooding was
observed across all of the upper midwestern states, with the Neosho
River in Kansas and the Illinois River in Illinois causing the worst
known flooding in U.S. recorded history."

Anyone might be forgiven for thinking this was the end of the
affair....

It was merely the end of the beginning:

"In mid-December 1926, the storms began anew across the Mississippi
Valley, with snow falling across the north and rain to the south and
east. To the north, Helena, Montana was hit with close to 30 inches of
snow.

To the south in Little Rock, Arkansas, close to 6 inches of rain fell
in one day. By Christmas, thousands were left homeless due to the
flooding and railroad traffic was suspended across the Mississippi
River. Many rivers rose to their highest levels ever recorded and the
gauge readings across the Ohio, Missouri, and Mississippi rivers from
October to December 1926 were at the highest ever known.

For example, the gauge at Vicksburg, Mississippi along the Mississippi
River in October 1926, which usually was around zero at that time of
year, was over 40 feet (12 meters). This gauge reading foreshadowed
the events to come, as high waters in the spring were expected to
follow.

In early January, no storms brewed over the region, but beginning in
mid-January, the rains
began to fall again. The Ohio River flooded Cincinnati on January 28,
1927. In early February, the
White and Little Red rivers flooded over 100,000 acres in Arkansas.
Rains continued through the
end of the month. In early March, a blanket of snow fell from the
Rockies to the Ozarks in the
north and rain deluged areas to the south in the lower Mississippi
Valley. For example, in
Mississippi, four inches (10 centimeters) of rain fell on March 16.
Then, from March 17 to March
20, three tornadoes touched down in the lower Mississippi Valley,
killing 45 people and damaging
the levees protecting the surrounding region. By the end of March
1926, every levee board south of
Cairo was operating 24 hours a day, patrolling the levees for breaches
and sandbagging the levees to
prevent overtopping.

The month of April brought no respite from the rain, and the rivers of
the upper and lower
Mississippi Valley continued to rise. By the second week of April,
over 1 million acres of land were
underwater and more than 50,000 people were driven from their homes
and living in temporary
shelters in Arkansas, Illinois, Kentucky, Mississippi, Missouri,
Oklahoma, and Tennessee. The
upper and lower Mississippi River - from Iowa to Louisiana - was in
flood stage. On April 13,
tornadoes once again touched down in the region. But the worst was yet
to come for Louisiana.
On April 15 (Good Friday), New Orleans received 15 inches (38
centimeters) of rain over the
course of 18 hours, totaling over one-quarter of the city's annual
average. Farther north,
Greenville, Mississippi received over 8 inches (20 centimeters) of
rain; between 6 and 15 inches (15
and 38 centimeters) fell in other counties along the Mississippi
River. On the same day, the New
York Times reported that "From Cairo to the sea, the most menacing
flood in years was sweeping
down the Mississippi River and its tributaries tonight." A follow-up
article showed pictures of
downtown New Orleans with 4 feet (1.2 meters) of standing water,
mistakenly stating that the
flooding was due to Mississippi River overflow rather than heavy
rainfall. Some of the political
leaders of the Delta states raised serious doubts about the levees
holding back the waters of the
river.

Then, on April 16, approximately 1,200 feet (366 meters) of levee at
Dorena, Missouri, which
lay only 30 miles (48 kilometers) south of Cairo, Illinois, collapsed.
This breach flooded 175,000
acres of land. The volume of water flowing down the Mississippi River
was unprecedented; in
1927, the Mississippi River south of Cairo carried a volume of water
measuring at least 1.7 million
cubic feet per second (cusecs) and possibly 2 million cusecs. In 1844,
the record flow of the river
near St. Louis was 1.3 million cusecs; in 1993, the volume was 1.03
million cusecs.
It was inevitable that another breach would happen, but there was
uncertainty as to where it
would occur. As a result, thousands of men struggled to reinforce the
levee along the lower
Mississippi River with sandbags. Then, on Thursday, April 21 at 8:00
am, the levee broke at
Mounds Landing, which lay below the junction with the Arkansas River
and approximately 12 miles
(19 kilometers) north of Greenville, Mississippi. Greenville was
flooded the next day. The breach
measured over 3,960 feet (1,207 meters) wide and 100 feet (30 meters)
deep, flooding the
Mississippi Delta with a volume of water measuring 468,000 cusecs. In
only ten days, 1 million
acres of land across the delta were immersed under water at least 10
feet (3 meters) deep. In 2007,
a deep still lake remains at the point where the former levee was
breached, eroding the underlying
delta sediments.
More breaches along the levee occurred farther to the south through
the months of April and
May, as the floodwater was channeled back once again through the
levees and into the Mississippi
River at Vicksburg, Mississippi. On May 24, the final breach of the
1927 flood occurred at McCrea,
Louisiana on the east bank of the Atchafalaya levee (Figure 3 shows
the full extent of the flood).

I haven't edited it properly yet as I need to reinstall Office but
your post was begging for it. So there you have the full 9 yards.

I need more weather references to take me to the end of May from where
the above account left off.

If this week's weather is anything to go by, the last of the spells
would have been desultory, so less inclination for journalism to
indulge us.

OTOH of course, the MetO was prophesying doom and there were some
places that got wet.