Earthquakes radiate waves with periods of tenths of seconds to several minutes. Rocks behave like elastic solids at these frequencies. Elastic solids allow a variety of wave types and this makes the ground motion after an earthquake or explosion (called an event) quite complex. There are two basic types of elastic wave: one involving compression and rarefaction of the elastic material in the direction of propagation of the wave, and one involving no compression but shear of the elastic material perpendicular to its direction of propagation. These are called P and S waves respectively, for primary and secondary since the P wave travels fastest and arrives first.

What scientists have only recently discovered is that the more familiar earthquakes, those that are easily measured while in progress and instantaneous in their destruction, are often preceded by longer, slow-moving, catastrophic disruptions rumbling twenty miles or more beneath us, too deep to be felt and too quiet to be measured for most of human history.

Once you have been in an earthquake you know, even if you survive without a scratch, that like a stroke in the heart, it remains in the earth's breast, horribly potential, always promising to return, to hit you again, with an even more devastating force.

Listen to the sound of the earth turning.

The earthquake, however, must be to every one a most impressive event: the earth, considered from our earliest childhood as the type of solidity, has oscillated like a thin crust beneath our feet; and in seeing the laboured works of man in a moment overthrown, we feel the insignificance of his boasted power.

If we come down to the other end of this great gamut, to very slow vibrations, we shall find a certain number so slow as to affect the heavy matter of the atmosphere to strike upon the tympanum of our ear and reach us as sound there may be, and there must be, an infinity of sounds which are too high or too low for the human ear to respond to them; and to all such sounds, of which there must be millions and millions, the human ear is absolutely deaf. If there be vibrations so slow that they appear to vs as sound, and other exceedingly rapid ones which appear as light, what are all the others? Assuredly there are vibrations of all intermediate rates We have them as electrical phenomena of various kinds; we have them as the Rontgen rays. In fact, the whole secret of the Rontgen rays, or X-rays, is simply the bringing within the capacity of our eyes and within the field of our vision a few more rays, a few of the finer rates of vibration, which normally would be out of our reach

Earthquakes generate elastic waves when one block of material slides against another; the break between the two blocks being called a fault. Explosions generate elastic waves by an impulsive change in volume in the material. Small explosive charges are used in controlled-source seismic experiments in which the waves penetrate only a few kilometres into the earth.

The drum lets us hear the heartbeat of the earth.

The shrill echoes ring amidst the skies.

Three days after the ’64 earthquake in Los Angeles, a television news reporter asked a survivor who had been near the epicenter how long the quake had lasted.
“It’s still going on,” the survivor said calmly.

When an object impacts the Moon at high speed, it sets the Moon slightly wobbling. Eventually the vibrations die down but not in so short a period as eight hundred years. Such a quivering can be studied by laser reflection techniques. The Apollo astronauts emplaced in several locales on the Moon special mirrors called laser retroreflectors. When a laser beam from Earth strikes the mirror and bounces back, the round-trip travel time can be measured with remarkable precision. This time multiplied by the speed of light gives us the distance to the Moon at that moment to equally remarkable precision. Such measurements, performed over a period of years, reveal the Moon to be librating, or quivering with a period (about three years) and amplitude (about three meters), consistent with the idea that the crater Giordano Bruno was gouged out less than a thousand years ago.

Every challenge we take on has the power to knock us to our knees. But what’s even more disconcerting than the jolt itself is our fear that we won’t withstand it. When we feel the ground beneath us shifting, we panic. We forget everything we know and allow fear to freeze us. Just the thought of what could happen is enough to throw us off balance. What I know for sure is that the only way to endure the quake is to adjust your stance. You can’t avoid the daily tremors. They come with being alive. But I believe these experiences are gifts that force us to step to the right or left in search of a new center of gravity. Don’t fight them. Let them help you adjust your footing.

We do not realize the sound the world makes-unless of course, it comes to a stop. Then, when it starts, it sounds like an orchestra.
Breaking waves. Whipping wind. Falling rain. Squawking birds. All throughout the universe, time resumed and nature sang.

Our hearts resonate at the same frequency as the earth and the universe. Therefore, we are all valuable instruments in the orchestration of the world and its harmony. We must always be aware of the vibrations we emit individually and collectively. Always be in command of your music. Only you can control and shape its tone. If life throws you a few bad notes or vibrations, don't let them interrupt or alter your song.