This is one of my earliest successful speeches. I competed in several High School competitions, often earning a fifth-place certificate. My father helped me with the cadence and rhythm, but the writing and research are all mine. Later, after the Loma Prieta quake (which I got to experience first hand), I updated it and used it as one of my speeches in Toastmasters. This is the updated version.
The summer of 1776, Muskingum River, Ohio.
1835, Concepcion, Chile.
1906, San Francisco.
1971, San Fernando Valley.
What do all these have in common? Tremor, terror, and tragedy.
Going through what we have been going through these past few months, we are very much aware of earthquakes. One can be felt somewhere in the world every ten minutes. And in a year, 1 in 50 will cause damage.
Maybe some of you remember the 1969 Santa Rosa quake. I remember and I was halfway around the world. For it hit the front page of the Nairobi newspapers along with pictures of leveled county offices. Chimneys had fallen, underground pipes had ruptured and sidewalks had buckled. Virtually every store in the downtown area sustained broken windows. The damage was estimated at six million dollars.
Throughout the ages, man has been fascinated by earthquakes, building myths around them from giants underground to fish jumping in underground streams. But what are earthquakes, really?
Well, picture two plates stuck together, one going one way, the other going the opposite. The pressure and strain, they snap. That is an earthquake.
The plates I am talking about are called tectonic plates. The earth’s crust is divided into these 10 to 60 mile thick slabs or plates. They move around on a current of magma, deep inside the earth, called the mantle. Because of this movement, a movement so slow we are virtually unaware of it, North America and Europe are moving apart at the rate of an inch a year. And Los Angeles is moving up toward San Francisco at the rate of two inches a year.
This movement also causes faults to form. A fault is a crack or fracture in the earth, where rocks on either side of the fracture have been displaced so that the layers no longer match. There are two kinds of faults: the strike-slip, which moves in a horizontal motion (back and forth), and the dip-slip, which moves in a vertical (up and down). The San Andreas Fault, our favorite, which knifes 600 miles through California, from Mexico, through San Francisco into the Pacific Ocean, is a strike-slip fault.
What causes faults to form and earthquakes to happen? Well, scientists believe that there is an earth wave moving at about 70 miles a year beneath the crust. They call this wave a deformation front. There are two theories as to what causes a deformation front.
One is that the spreading plates are unable to accommodate a sudden pulse of magma, thus causing the wave. The crust contracts and expands to permit passage of the wave. When the wave hits a heavily stressed fault, an earthquake results.
The second idea is that there are convection currents in the magma. These currents circulate slowly, rising to the crust and sinking again. Now, if this hot, viscous material gets hotter or undergoes more stress it thins. And this surge of thinned material, followed by thick, releases elastic energy stored in the current, thus creating the deformation front. When the front hits a stressed fault, an earthquake happens.
Earthquakes have other side effects besides the earth shaking. They are very subtle, but with the right instruments, they can be detected and even forewarn of an earthquake.
One way geophysicists detect earthquakes is with radon wells. These wells are specifically drilled to sample radon, an element in the earth. They are usually four to six inches across and about 100 feet deep.
In regions where stresses are building, the level of radon builds for weeks or months until it reaches a peak and then takes about the same amount of time to decline to its original level.
The Chinese say when the radon levels are almost back to normal, earthquakes happen. The Russians say they happen when the radon has reached a bottom and is on its way up again.
The radon level changes are caused by the layers of rock beneath the surface being subjected to mounting tension as the land masses on the opposite sides of the fault try to move past each other and begin to crack. This increases their surface area and opens numerous tiny pores, allowing more radon to escape.
Another side effect is the eerie lights that often accompany earthquakes. This is apparently caused by a powerful electric field generated by the shifting rocks. Geophysicists at the US Geological Survey have found that the heat of rocks sliding along a fault vaporizes water in the rocks. Electric charges within the water collect near the fault, attracting ions in the atmosphere and making them glow as they move through the electric field.
Animals also help forewarn that an earthquake is imminent. For some reason, animals behave strangely before an earthquake. For example the howling of dogs before the 1906 San Francisco quake and the immense flock of screaming sea-birds that appeared over Concepcion, Chile, before it was destroyed in 1835. The list goes on and on. Scientists think that odorants released into the air by shifting rocks could be the cause, but they are unsure.
Although earthquakes have their destructive side, they also have a beneficial side. For one, if there were no seismic waves, we would be unaware of what’s happening on our planet. And two, mountains are constantly eroding, if earthquakes didn’t push them back up, the world would become flat; one of stagnant seas and swamps. Seismic waves are the pulse beats of our planet. If they were to stop, ours would indeed be a dead world.