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Re: Quakes Shift Whole Island Of Sumatra...

Marc:

Magnitude 9 is 10 times more powerful than a Magnitude 8. Magnitude 10 is 10 times more powerful than a Magnitude 9, which means that it is 100 times more powerful than a Magnitude 8 (and 1000 times more powerful than a Magnitude 7, and 10,000 times more powerful than a Magnitude 6, etc).

From the U.S.G.S. [US Geological Survey] (see 
http://pubs.usgs.gov/gip/earthq1/measure.html):

"The severity of an earthquake can be expressed in several ways. The magnitude of an earthquake, usually expressed by the Richter Scale, is a measure of the amplitude of the seismic waves. The moment magnitude of an earthquake is a measure of the amount of energy released - an amount that can be estimated from seismograph readings. The intensity, as expressed by the Modified Mercalli Scale, is a subjective measure that describes how strong a shock was felt at a particular location.

The Richter Scale, named after Dr. Charles F. Richter of the California Institute of Technology, is the best known scale for measuring the magnitude of earthquakes. The scale is logarithmic so that a recording of 7, for example, indicates a disturbance with ground motion 10 times as large as a recording of 6. A quake of magnitude 2 is the smallest quake normally felt by people. Earthquakes with a Richter value of 6 or more are commonly considered major; great earthquakes have magnitude of 8 or more on the Richter scale.

The Modified Mercalli Scale expresses the intensity of an earthquake's effects in a given locality in values ranging from I to XII. The most commonly used adaptation covers the range of intensity from the condition of "I -- Not felt except by a very few under especially favorable conditions," to "XII -- Damage total. Lines of sight and level are distorted. Objects thrown upward into the air." Evaluation of earthquake intensity can be made only after eyewitness reports and results of field investigations are studied and interpreted. The maximum intensity experienced in the Alaska earthquake of 1964 was X; damage from the San Francisco and New Madrid earthquakes reached a maximum intensity of XI."

It seems to me that this quake is probably an X or an XI on this scale - but we'll need to see after everything is compiled.

Lest we think that this current catastrophe is the worst ever (but not to diminish the horror or tremendous loss), here is some info about 2 Chinese quakes (This is from http://www.drgeorgepc.com/EarthquakesChina.html - "The Tsunami Page of Dr. George P. C." [Excerpts from Unpublished Manuscript - by George Pararas Carayannis])

"The Great China Earthquake of 1556
The worse natural disaster in recorded history, at least in terms of lives lost, was caused by an earthquake in Hausien in the Shensi Province of China in 1556. The earthquake devastated 98 counties and eight provinces of Central China. The destruction spanned an area of 500 miles, and in some counties the average death toll was 60 percent of the population. A total of 830,000 people lost their lives, most of them from the collapse of poorly constructed houses. The magnitude of this earthquake has been estimated to be from 8.0 to 8.3 on the Richter scale.

The China Earthquake of 1976
No other earthquake in this century has been as catastrophic or has claimed as many lives as the great earthquake that struck the city of Tangshan, in Northern China, on July 28, 1976.

Tangshan, a thriving industrial city with one million inhabitants, is located only about 95 miles east, and slightly south, of Beijing. Although the region had experienced moderate seismic activity in the past, the city of Tangshan has been built on unstable, alluvial soil. To make matters worse, The city is located in the center of an area with major crustal faults on four sides. Furthermore, a 25-mile long fault passes through Tangshan, where only few of its structures are earthquake-resistant.

In the early morning hours of July 28, while the city was asleep, the magnitude 8.0 earthquake with its epicenter right on the city broke a five-mile section of the fault. Along the west side of the fault the land moved five feet northward in relation to the land on the east side. The east block tipped downward at the northern end of the break, and upward toward the south end. Over a four-by-five mile area the devastation of the city was nearly total. The force of the quake motions were so strong that people reported being thrown in the air. Within seconds, thousands died. Property destruction was unbelievable. Bridges, railroads, homes, factories were completely leveled.

In the harbor city of Tientsin, 60 miles to the southwest, and in Beijing to the west, the quake jolts forced thousands of frightened people into the streets seeking refuge from aftershocks.

The extent of the destruction and number of deaths in Tangshan and elsewhere in China was never disclosed officially. However, based on the density of population, it was fairly accurately estimated that there were at least 655,000 people dead, and 780,000 injured. These figures make the 1976 Tangshan earthquake, the second worse earthquake in recorded history. The most destructive earthquake ever, as reported earlier, occurred at Hausien in China's Shensi Province in 1556. "

Allan Edels

P.S. New Year's for the fourth time in the last four months???? I only celebrate twice in 4 months! :-)

From: Mar Qos Aker <marqosaker@yahoo.com>
To: edels@msn.com, dinosaur@usc.edu
Subject: Re: Quakes Shift Whole Island Of Sumatra...
Date: Wed, 29 Dec 2004 11:08:59 -0800 (PST)



Allan Edels <edels@msn.com> wrote:
David:

The initial reports said it was an 8.9 magnitude, but later reports have it
as a 9.0 (tieing a Russian quake [Kamchatka?] for the 4th strongest known
recorded earthquake). The scale is logarithmic which means that a 9 is 10
times more powerful than an 8. [But I really didn't need to tell you that -
that's just for our viewers :-) ].


>I thought it was 8.9 (isn't 9.0 about, like, half again as strong as 8.9?),
>and I thought it was 25 km = 15.6 miles beneath the surface?

Does a magnitude of 9 in earthquakes mean 10 times or 2 times as strong as an earthquake with magnitude of 10. I would appreciate a reference, if I am wrong. I thought it was a natural log. . . like e or whatever. I admit hereby my ignorance. I fairly ignorant about deenos, as my posts have made plain, but I am out of my league with earthquakes, other than seismos is gk for earthquake, or just quake, which is my point.

Thanks for the jawboning. To be able to celebrate New Year's for the fourth time in the last four months and with you deeno lovers is my greatest discovery, else I would not not of the discoveries that you all have shared with me. Again many thanks. Marc Bauer



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