A Quick Look At Some Famous Earthquakes
To gain entry in one's list of famous earthquakes, the event must either be of a very high magnitude, cause great loss of life, or cause massive destruction. The more famous ones are usually are characterized by at least two of these three factors. The most recent earthquakes of note are the 2008 quake in the Sichuan province of China, and the 2004 quake in Sumatra, Indonesia, which gave birth to an even more devastating tsunami.
Loss of life and property destruction are naturally going to occur where an earthquake happens in a heavily populated area. Earthquakes of a magnitude equal to that of the Sumatra quake have been recorded, but have occurred in areas having little or no population. A couple of these are included in our listing of famous earthquakes.
What Causes An Earthquake? - Certain areas on our planet are more susceptible to earthquakes than others. This is because the surface of the earth consists of plates, called tectonic plates, which are in constant, though very slow, motion. When two of these plates come together, one generally begins to slide underneath the other. At the surface, the movement of these plates is usually not noticeable to humans, although sensitive instruments can detect them. Occasionally a plate will become stressed in its attempt to move and when finally "breaking free” with a lurching motion, causes the earths surface to move and we feel it as an earthquake. An earthquake often means that things have returned to normal, and the plates are no longer stressed, or will not become so again for a number of years. Then we'll experience another quake. When these movements are sufficiently large to cause massive earth movement, we can add to our list of famous earthquakes.
The larger earthquakes then, are usually the result of this tectonic movement, but can also arise from a fault occurring in one of the plates. This was the case behind the New Madrid (Missouri) earthquakes of 1811 - 1812. The entire Mississippi valley felt this quake, estimated to be a Magnitude 8.0 earthquake, and it is one of the more famous earthquakes to have happened in the continental United States. The Mississippi Valley does not lie on a fault line, so the quake was in no way expected. It occurred due to a fault in the tectonic plate itself, not from any interaction between plates, the usual cause. Small, localized earthquakes also are felt from time to time, resulting from events such as volcanic activity. Many earthquakes were recorded prior to the eruption of Mount St. Helens in 1980. Some could be felt, but most were of a very low magnitude. The eruption itself was the big ground shaker.
As far as famous earthquakes go, we tend to place them on the list of famous earthquakes depending on where we live. A few centuries ago, a major earthquake could occur with great loss of life and property damage, yet most of the world would be unaware of it. Today, we learn of such a quake almost instantly, witness the recent quakes in China and Indonesia. International assistance begin to get underway almost as soon as the ground stopped shaking. In the United States, news of the New Madrid quake probably spread with the speed of the horse. On the other hand, with telephones and the telegraph in place, people on the east coast were made aware of the San Francisco quake almost immediately.
The San Francisco Quake - The 1906 San Francisco Earthquake is estimated to have been somewhere between a Magnitude 7.7 and 8.3. It was huge in the area covered, having been caused by a 300 mile long rupture in the San Andreas fault. The epicenter was close to the city of San Francisco, and the duration of the quake itself lasted nearly a minute. The quake was felt throughout the state of California, and into Oregon and Nevada. The exact death toll has never been known exactly, but at least 900 people died, if not twice that number. As far as the city itself was concerned, what the quake didn't destroy or damage, the subsequent fire took care of. It was not unusual at the time for a major quake in a major city to be followed by fire. It still can happen of course, but in those days there were more open flames, and more wooden buildings to fuel the flames. Since the Great San Francisco quake, there have been others in California, include one not many years ago in the Bay area, as well as several in the greater Los Angeles area. While there has been some significant damage, the loss of life in recent quakes has been nothing compared to the 1906 quake. (continued...)