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Posts Tagged ‘California’

The earthquake that rocked Alaska on March 27, 1964 needs no special introduction.  It is the most powerful earthquake recorded in the Northern Hemisphere.  Only two others, the great Chilean earthquake of 1960 and the 2004 quake off Sumatra (which caused that terrible tsunami), have approached or surpassed the Alaskan quake’s strength, which struck in the Prince William Sound area shortly after 5:30pm on Good Friday.

Geologists believe that earthquakes occuring along subduction zones tend to be more powerful than quakes along standard fault lines, because greater stresses build up as the upper plate passes over the lower.  The Alaskan quake was of that type and, while I wasn’t alive when it happened, the pictures show tremendous damage.

The land buckled and heaved during the 4-minute quake, permanently rising as much as 30′ (the Kodiak area) in places while dropping 10′ in others, creating new beachlines and opening fissures in the surface.  In the photo above, you can see how the beach areas of Middleton Island on the left slid nearly 12′ from its original level on the right.

Of course, the forces we are discussing here were astronomically stronger than any man-made structures.  Anchorage was heavily damaged, as were a good number of smaller cities and towns.  In fact, significant damage was reported over an area covering more than 50,000 square miles from a quake that was felt over more than half-a-million square miles.  Thousands of major aftershocks over the next 18 months served to terrorize an already stunned populace trying to put their lives, homes, and infrastructure back together.  But its effects were even more far-reaching.

The rapid shift along the plates triggered tsunamis that were detected throughout the Pacific Ocean and caused widespread damage.  While deaths from the quake itself (falling buildings, etc.) were incredibly few (10-15, depending on your source), 120 fatalities were caused by tsunamis.  Crescent City, on California’s northern coast, was particularly hard hit, where 14-foot waves were responsible for 11 deaths and millions of dollars of damage.

But the location of the Alaskan earthquake (well off the equator in the upper Northern Hemisphere) also caused the planet to wiggle, which means that the effects of the quake were seen worldwide.  Small tsumani waves were detected in Cuba, small boats were reportedly capsized off Louisiana’s coasts, and water oscillations were seen in Africa.

Here in the central United States, we occasionally mention the fabled “big one” that supposedly will someday strike the San Andreas Fault and knock the most heavily-populated parts of California into the Pacific, while simultaneously casting a wary glance in the direction of the New Madrid Fault, knowing we stand on shaky ground ourselves.  But I think a good number of us would like to believe that “the big one” has already come and gone, striking the Alaskan coast 46 years ago (as of this writing).

Time will tell if that belief stands up to the motion of the tectonic plates.

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When one thinks of historical disasters in California, usually one of two events comes to mind…both involving earthquakes.  The first, and most obvious, is the earthquake and fire that struck San Francisco in 1906.  The second is the quake that again rocked the city in the fall of 1989.

But our topic of discussion this evening has nothing to do with earthquakes, though a whole lot of earth got moved.  Just before midnight on March 12, 1928, the St. Francis Dam collapsed, sending a tremendous wall of water (initially 125 feet high) screaming down the San Francisquito Canyon (roughly following the San Francisquito Canyon Road).

The causes of the failure were numerous, and go back almost to the start of construction in 1924.  Originally engineered as a 175-foot high dam, 10′ were added to the height in order to increase the water capacity.  Halfway through construction, yet another 10′ were added.  There were issues with material quality, proper design, and proper accounting for the bed on which the dam was built, but the height changes were probably the main problem.

When construction was completed, the dam began to fill without issue.  But as the dam reached capacity, the structural shortcomings came to light.  The additional height was not accompanied by enough width at the bottom to support the additional forces at the dam’s top.  So at 11:57pm, the pressure at the top of the dam sort of lifted the dam off its foundation and pushed it over.

More than 12 billion gallons ripped down the valley, at breakneck speed and with earth-gouging power.  Recall that when we talked about the terrible Johnstown Flood that occurred 40 years earlier, the collapsing South Fork Dam released less than half the volume of water.

Five and a half hours later, when the floodwaters reached the Pacific Ocean (more than 50 miles away), they carried homes, giant chunks of concrete and rock, parts of a hydroelectric plant, and the bodies of an estimated 600 people.  Upstream at the dam site, only the center section of the dam (shown above, aptly named the “Tombstone”) remained.

The collapse of the St. Francis Dam is a relative unknown in the list of California disasters, but it was one of the worst engineering disasters of the previous century.  In fact, in California’s history, only the dreadful 1906 earthquake resulted in a greater loss of life.

Recommended Reading: Directions to the St. Francis Dam – A nice pictoral of how to find the site of California’s second-worst disaster.

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The cold continues…-15 again this morning and the white car still doesn’t start.  It’s like a really bad saga.

When I mention that Today’s History Lesson has something to do with San Francisco, each of you will have different images pop into your brain.  For some, it’s the houses packed so tightly together (each of which costs a bundle to own).  For others, it might be the fog over the Bay.  Some may immediately think of the earthquakes that have, over the years, caused catastrophic damage to the area.

For me personally, it’s that one street that winds back and forth (the name escapes for the moment).  It’s the scenes from the movie Bullitt with Steve McQueen and his Mustang, where pursued became pursuer as they flew down those descending streets in one of the more dramatic car chases ever to grace the movie screen.  But the thing that probably comes to my mind first is the same thing for many of you as well…

The Golden Gate Bridge.

Along with the Empire State Building, Mount Rushmore, and the Statue of Liberty, the Golden Gate is likely one of the most recognizable man-made structures in America, if not the world.  It’s not the tallest, it’s not the longest (though it was when it was built), and it’s not the most expensive bridge ever built.  And it’s never had a major collapse to color its history, as others have.

But it, as much as any structure ever built, has demonstrated man’s ability to harness the rigid laws of physics and use them in a way that actually helps people.  Before the Bridge (in the early 1930’s), getting from San Francisco to Sausalito required a ride on a ferry across the Bay, or a drive of many hours around the Bay, taking advantage of whatever other bridges would serve to shorten the trip.  And while the ferry worked, it wasn’t so nice in heavy weather, and ferries could only move so many cars at a time.

The idea of a bridge, however, was looked on with skepticism.  The distance (6,700′) was daunting.  The weather and the winds and the waves would wreak havoc on a bridge.  The water in the middle of the proposed span was 500′ deep…driving pilings and pouring concrete and building supports would be very difficult.  And the harbor still had to support a significant shipping business as well as the needs of the U.S. Navy.  Nobody wanted ships constantly plowing into a bridge.  And of course, there were those occasional earthquake concerns.

The solution was a suspension bridge.  Two massive supports would be “planted” on the far ends of the bridge, which would prevent the expensive process of laying supports in deep water, while simultaneously removing a bunch of solid targets for ships to hit in bad weather.  Then, a bunch of cable would be strung between the supports and the bridge itself, providing the lift.  Of course, there’s a whole lot more physics and stuff involved, but I averaged a D+ in my two semesters of college physics, so I’m not the guy to explain it.

And on January 5, 1933, that’s what the workers started building.  Completed in 1937 and opened to traffic in May of that year, the Golden Gate runs almost 9,000′ from abutment to abutment.  It weighs in at a rather heavy 894,500 tons.  The bridge is supported and stabilized by 80,000 miles of high-tensile cable, which means two things.  First, it can hold up two tons of stuff (cars, trucks, and buses) per foot.  Second, the bridge offers significant flex (up to 15′ of total deflection) without collapse.

While I’ve visited California, I’ve never been to San Francisco nor seen the Golden Gate.  But I’d love to visit.  Getting my wife to actually cross the Golden Gate, however, well…

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On November 2, 1947, the largest flying boat ever constructed lifted off on its maiden flight near Long Beach, California.  Officially called the H-4 Hercules, it was built by billionaire aircraft designer (and noted eccentric) Howard Hughes, and it was immense.  The contract for three prototypes, which was awarded to Hughes in 1942 with the help of famous shipbuilder Henry Kaiser, came during wartime, when aircraft metals were scarce and mostly spoken for.  The size of the plane dictated that more abundant materials be used, so it was made almost entirely of birch wood.

The time required to design and build the prototype (partially due to Hughes’ fanatical attention to detail) meant that it was finished too late to serve in the Second World War, but it was still a very impressive aircraft.  It’s 320-foot wingspan was (and still is and probably will be in the future) the largest ever.  It’s also one of the tallest, with it’s rear stabilizer reaching nearly 80 feet skyward.

It was powered by eight 3000-horsepower Pratt and Whitney engines, the same engines powering the brand-new Convair B-36 Peacemaker.  Those engines (with a bit of jet assistance) would keep B-36’s aloft for more than a decade.

But for the H-4, just 30 seconds over the water would suffice, because that’s all the longer the flight lasted…and Howard Hughes’ labor of love would never fly again.  The public, in an attempt to ridicule this “one-flight-wonder”, called the plane the “Spruce Goose”.  Hughes loathed the name, and not just because the public got the type of wood wrong.  But it was the name that stuck.

Recommended Activity:  Visit the Evergreen Aviation and Space Museum – The Spr…the H-4 Hercules is there, along with a bunch of other cool stuff.

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