Download Earthquakes

Earthquakes
• An earthquake is a sudden rapid shaking of the earth.
• They are caused by the breaking and shifting of the rock
beneath the earth’s surface.
• Often found in conjunction with Plate tectonic
boundaries.
An earthquake can cause:
-buildings and bridges to collapse
-disrupt utility supply lines
-trigger landslides, avalanches, flash
floods, fires, and huge destructive ocean waves.
Earthquakes
Earthquakes
Residence in Los Gatos moved off
its foundation
Hector Mine surface rupture
Earthquake Location Map
Ninety percent of the
world's earthquakes
occur in specific areas
that are the boundaries
of the Earth's major
crustal plates. Shown
on the map are the
epicenter locations of
earthquakes of
magnitude 4.5 or
greater that occurred
from 1978 through
1987.
Ring of Fire
• The "Ring of Fire",
also called the
Circum-Pacific belt,
is the zone of
earthquakes
surrounding the
Pacific Ocean--about
90% of the world's
earthquakes occur
there.
Plate Boundary Types
• Convergent Boundaries
• Divergent Boundaries
• Transform Faults
Convergent Boundary
• Mountain Building
Convergent Boundary
• Subduction Zone
Divergent Boundary
• Sea Floor Spreading
Transform Fault
• Plates move past each other.
Most Recent Utah Earthquake
July 11, 2003 – Near Huntsville
Seismicity of the U.S 1975-1995.
Earthquake Measurements
• Magnitude – Richter Scale
Energy released during the earthquake
• Intensity – Mercalli Scale
Damage or loss of life caused by the
earthquake
Richter Scale
• Invented by Charles
F. Richter in 1934
• The Richter magnitudes
are based on a
logarithmic scale (base
10). What this means is
that for each whole
number you go up on the
Richter scale, the
amplitude of the ground
motion recorded by a
seismograph goes up ten
times.
Richter Scale Measurement
• Richter Scale is calculated using a
seismograph
Seismometer
• A seismograph, or
seismometer, is an
instrument used to
detect and record
earthquakes.
Generally, it consists
of a mass attached to
a fixed base. During
an earthquake, the
base moves and the
mass does not.
Locating Earthquakes
Richter Scale
• 3.5-5.4 Often felt, but rarely causes damage.
• Under 6.0 At most slight damage to well-designed
buildings. Can cause major damage to poorly
constructed buildings over small regions.
• 6.1-6.9 Can be destructive in areas up to about 100
kilometers across where people live.
• 7.0-7.9 Major earthquake. Can cause serious damage
over larger areas.
• 8 or greater Great earthquake. Can cause serious
damage in areas several hundred kilometers across.
Mercalli scale
• Invented by Giuseppe
Mercalli in 1902,
• This scale uses the
observations of the
people who
experienced the
earthquake to
estimate its intensity.
Mercalli Scale
• I. Not felt except by a very few under especially favorable
circumstances.
• II. Felt only by a few persons at rest, especially on upper floors of
buildings. Delicately suspended objects may swing.
• III. Felt quite noticeably indoors, especially on upper floors of
buildings, but many people do not recognize it as an earthquake.
Standing automobiles may rock slightly. Vibration like passing of
truck. Duration estimated.
•
IV. During the day felt indoors by many, outdoors by few. At night
some awakened. Dishes, windows, doors disturbed; walls make
creaking sound. Sensation like heavy truck striking building.
Standing automobiles rocked noticeably.
Mercalli Scale Cont.
• V. Felt by nearly everyone, many awakened. Some dishes,
windows, and so on broken; cracked plaster in a few places;
unstable objects overturned. Disturbances of trees, poles, and other
tall objects sometimes noticed. Pendulum clocks may stop.
• VI. Felt by all, many frightened and run outdoors. Some heavy
furniture moved; a few instances of fallen plaster and damaged
chimneys. Damage slight.
• VII. Everybody runs outdoors. Damage negligible in buildings of
good design and construction; slight to moderate in well built
ordinary structures; considerable in poorly built or badly designed
structures; some chimneys broken. Noticed by persons driving cars.
• VIII. Damage slight in specially designed structures; considerable in
ordinary substantial buildings with partial collapse; great in poorly
built structures. Panel walls thrown out of frame structures. Fall of
chimneys, factory stack, columns, monuments, walls.Heavy furniture
overturned. Sand and mud ejected in small amounts. Changes in
well water. Persons driving cars disturbed.
Mercalli Scale Cont.
• IX. Damage considerable in specially designed structures; well
designed frame structures thrown out of plumb; great in substantial
buildings, with partial collapse. Buildings shifted off foundations.
Ground cracked conspicuously. Underground pipes broken.
• X. Some well built wooden structures destroyed; most masonry and
frame structures destroyed with foundations; ground badly cracked.
Rails bent. Landslides considerable from river banks and steep
slopes. Shifted sand and mud. Water splashed, slopped over banks.
• XI. Few, if any, (masonry) structures remain standing. Bridges
destroyed. Broad fissures in ground. Underground pipelines
completely out of service Earth slumps and land slips in soft ground.
Rails bent greatly.
• XII. Damage total. Waves seen on ground surface. Lines of sight
and level distorted. Objects thrown into the air.
Earthquake Terminology
• Epicenter – area on the earths surface directly
above the focus or hypocenter
• Fault – area of two surfaces of rock move
passed one another
• Focus – actual location of the earthquake
• Hypocenter – same as the focus
Types of Earthquake Waves
• Primary or P waves
• Secondary or S waves
• Surface or L waves
Body waves
Surface waves
Tsunami
• Tsunamigenic is
referring to those
earthquakes,
commonly along
major subductionzone plate boundaries
such as those
bordering the Pacific
Ocean, that can
generate tsunamis.
Destructive Earthquakes
• Date
Location
Deaths
Mag
Comments
• January 23, 1556 China, Shansi
830,000
• July 27, 1976
China, Tangshan 255,000* 8.0 Estimated
death toll (official) as high as 655,000.
• August 9, 1138 Syria, Aleppo
230,000
• May 22, 1927
China, near Xining 200,000 8.3 Large fractures.
• December 22, 856+ Iran, Damghan
200,000
• December 16, 1920 China, Gansu
200,000 8.6 Major
fractures, landslides.
• March 23, 893+ Iran, Ardabil
150,000
• September 1, 1923 Japan, Kwanto 143,000 8.3 Great Tokyo fire.
• October 5, 1948 USSR
110,000 7.3 (Turkmenistan,
Ashgabat)
• December 28, 1908 Italy, Messina 70,000 7.5 Deaths from
100,000 earthquake and (estimated) tsunami.
Annual Earthquakes
•
•
Magnitude
Average Annually
Great 8 and higher
1
•
Major
7 _ 7.9
18
•
Strong
6 _ 6.9
120
•
Moderate
5 _ 5.9
800
•
Light
4 _ 4.9
6,200 (estimated)
•
Minor
3 _ 3.9
49,000 (estimated)
• Very Minor
2 _ 3:
about 1,000 per day
1 _ 2:
about 8,000 per day
Earthquakes 1900's
•
•
•
•
•
•
•
•
•
•
1. Chile
1960 05 22
2. Prince William Sound, Alaska
1964 03 28
3. Andrean of Islands, Aleutian Islands 1957 03 09
4. Kamchatka
1952 11 04
5. Off the Coast of Ecuador
1906 01 31
6. Rat Islands, Aleutian Islands
1965 02 04
7. India_China Border
1950 08 15
8. Kamchatka
1923 02 03
9. Banda Sea, Indonesia
1938 02 01
10. Kuril Islands
1963 10 13
9.5 Mw
9.2 Mw
9.1 Mw
9.0 Mw
8.8 Mw
8.7 Mw
8.6 Mw
8.5 Mw
8.5 Mw
8.5 Mw
Remember
It’s not
“ If ”
But
When!!!!!!!
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