Category Archives: Earthquake

Understanding The Richter Scale

The Richter Scale

The now-famous Richter scale was developed in 1935 by Charles Richter of the California Institute of Technology. The scale was intended only for use in California to separate the large number of small earthquakes from the small number of larger ones. The scale is derived from astronomy’s stellar magnitude scale.

The scale assigns a number to quantify the size of the earthquake. The number is derived by calculating the logarithm of the combined horizontal amplitude of the largest displacement from zero on a seismogram. It is a logarithmic scale, so an earthquake of five is ten times greater than a four, and an eight is 10,000 times greater than a four.

The energy of the earthquake is proportional to the square root of the cube of the amplitude. So each step of of the scale has an energy 31.6 times that of the previous. A nine, therefore, has 10,000 times the amplitude of a five, but a million times more energy.

Originally posted 2015-01-05 02:18:28.

Worst Earthquakes Worldwide by Magnitude

Largest Earthquakes Worldwide
In Terms of Magnitude

1.
Chile
May 22, 1960
Magnitude: 9.5

2.
Prince William Sound, Alaska
March 28, 1964
Magnitude: 9.2

3.
Aleutian Islands
March 9, 1957
Magnitude: 9.1

4.
Kamchatka, Russia
Nov. 4, 1952
Magnitude: 9.0

5.
Sumatra, Indonesia
Dec. 26, 2004
Magnitude: 9.0

6.
Japan
March 11, 2011
Magnitude: 8.9

7.
Ecuador
Jan. 31, 1906
Magnitude: 8.8

Chile
February 27, 2010
Magnitude: 8.8

8.
Aleutian Islands
Feb. 4, 1965
Magnitude: 8.7

9.
Sumatra, Indonesia
March 28, 2005
Magnitude: 8.7

10.
India-China border
Aug. 15, 1950
Magnitude: 8.6

11.
Kamchatka, Russia
Feb. 3, 1923
Magnitude: 8.5

Originally posted 2015-01-05 02:15:36.

Earthquake Facts

  • Several million earthquakes occur every year. Most go unnoticed because they are very small, or because they occur in very remote areas. There is no scientific evidence to suggest that animals can predict earthquakes.
  • The moon does not influence earthquakes.
  • California is NOT going to fall into the ocean. The Pacific Plate and North American plates are moving sideways to one another. California earthquakes along the San Andreas Fault are strike-slip quakes. However, sometime in the very distant future, San Francisco and Los Angeles will be adjacent to each other.
  • There is no evidence that we are having any more or less earthquakes than in the past. If it seems like there are more, that is because areas that formerly were unpopulated now have people, and because sensitive instruments now can detect previously undetectable tremors.
  • Volcanos do not cause earthquakes. However, they often occur in the same areas because the same forces that cause volcanos (plate tectonics) also cause earthquakes.
  • Originally posted 2015-01-05 02:16:56.

    The Worst US Earthquakes By Death Toll

    The Worst US Earthquakes
    Deadliest US Earthquakes

    As Measured By Death Toll

    The United States’ Worst Earthquakes
    As Measured By Death Toll

    1.
    The Great San Francisco Earthquake
    April 18, 1906
    Magnitude: 7.8
    Death Toll: 3,000

    The Great San Francisco Earthquake is by far the deadliest ever to hit the United States.

    2.
    Aleutian Islands, Alaska
    April 1, 1946
    Magnitude: 8.1
    Death Toll: 165

    Most of the deaths from this earthquake were in Hawaii, as the resulting tsumami killed 159. Five were killed in Alaska; 1 in California.

    3.
    The Good Friday Earthquake
    Prince William Sound, Alaska
    March 28, 1964
    Magnitude: 9.2
    Death Toll: 125

    The strongest earthquake to ever hit the United States caused a tsunami that killed 98 in Alaska, 11 in California, and one in Oregon. Fifteen were killed in Alaska as a direct result of the quake. The effects of the quake were felt worldwide: several fishing boats were reported sunk off of Louisiana, and wells were seen sloshing water in South Africa.

    4.
    Long Beach, California
    March 11, 1933
    Magnitude: 6.3
    Death Toll: 115

    Poor building design led to the deaths of 115 as people were killed by falling debris as they ran out of buildings. The quake led to a mandate in California that scool buildings be earthquake resistant.

    5.
    Hawaii Island, Hawaii
    April 3, 1868
    Magnitude: 7.9
    Death Toll: 77

    Thirty one died from landslides; 46 from the resulting tsunami.

    Originally posted 2015-01-05 02:12:22.

    The World’s Deadliest Earthquakes

    The World’s Worst Earthquakes

    As measured by the death toll.

    The worst earthquakes in history, in terms of the death toll have  occurred in China. In addition to lying along the earthquake prone “ring of fire”, China also has historically had a high population density. This virtually ensure that the highest earthquake casualties will be in China. It also is helpful that the Chinese have long had efficient bureaucracies, which were able to document the casualties as long ago as the 1500s.

    1.

    Shaanxi Province, China
    January 23, 1556
    Magnitude: approximately 8
    Death Toll: 830,000

    2.
    Tangshan, China
    July 28, 1976
    Magnitude: 7.5
    Death Toll: 242,000
    The casualties in this may have been higher. The Chinese government is thought to have deliberately understated the numbers for political reasons.

    3.
    Aleppo, Syria
    August 9, 1138
    Magnitude: ?
    Death Toll: 230,000

    4.
    Haiti
    January 12, 2010
    Magnitude: 7.0
    Death Toll: 222,517

    5.
    Xining, China
    May 22, 1927
    Magnitude: 7.9
    Death Toll: 200,000

    6.
    Damghan, Iran
    December 22, 1856
    Magnitude: unknown
    Death Toll: 200,000

    7.
    Gansu, China
    December 16, 1920
    Magnitude: 8.6
    Death Toll: 200,000

    8.
    Ardabil, Iran
    March 23, 893
    Magnitude: ?
    Death Toll: 150,000

    9.
    Kwanto, Japan
    September 1, 1923
    Magnitude: 8.3
    Death Toll 143,000

    10.
    Ashgabat, Turkmenistan, USSR
    October 5, 1948
    Magnitude: 7.3
    Death Toll: 110,000

    11.
    Messina, Italy
    December 28, 1908
    Magnitude: 7.2
    Death Toll: 100,000

    Originally posted 2015-01-05 02:10:17.