Introduction
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MEASURING
MAGNITUDE
Description
When
scientists refer to a "great" earthquake, they
do not mean the earthquake was fabulous, they mean it was
huge, Informally, earthquakes are classified according to
their size.
| Magnitude |
Desc. |
| Under
5 |
small |
| 5
- 6 |
moderate |
| 6
- 7 |
large |
| 7
- 8 |
major |
| 7.8
or above |
great |
| Magnitude |
Date |
Location |
Length
in
Kilometers |
Duration
seconds |
| 7.8 |
January 8,
1857 |
Fort Tejon |
360 |
130 |
| 7.7 |
April 18,
1906 |
San Francisco |
400 |
110 |
| 7.5 |
July 21, 1952 |
Kern County |
75 |
27 |
| 7.3 |
June 28, 1992 |
Landers |
70 |
24 |
| 7.0 |
October 17,
1989 |
Loma Prieta |
40 |
7 |
| 6.9 |
May 18, 1940 |
Imperial Valley |
50 |
15 |
| 6.7 |
January 17,
1994 |
Northridge |
14 |
7 |
| 6.6 |
November 24,
1987 |
Superstition
Hills |
23 |
16 |
| 6.5 |
April 9, 1968 |
Borrego
Mountain |
25 |
6 |
| 6.4 |
October 15,
1979 |
Imperial Valley |
30 |
13 |
| 6.4 |
March 10,
1933 |
Long Beach |
15 |
5 |
| 6.1 |
April 22,
1992 |
Joshua Tree |
15 |
5 |
| 5.9 |
July 8, 1986 |
North Palm
Springs |
20 |
4 |
| 5.9 |
October 1,
1987 |
Whittier
Narrows |
6 |
3 |
| 5.8 |
June 28, 1991 |
Sierra Madre |
5 |
2 |
-
These
are the fastest-slipping faults, moving at a rate of at
least 4 millimeters per year. The Newport-Inglewood
fault, although famous, moves less than 0.5 millimeter per
year, slower than many others in Southern California.
-
*550
kilometers of the San Andreas fault are in Southern
California, south of Parkfield.
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