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Earth Processes:Earthquakes
Dr. K. Vijaya Kumar
School of Earth SciencesSRTM University, Nanded 431 606Maharashtra, INDIA
(E-mail: [email protected])
Lecture 22 and 23
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Global Earthquake Locations
At the boundaries between plates, friction causes them to
stick together. When built up energy causes them to break,
earthquakes occur
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Plate Boundaries and Earthquakes
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Where do earthquakes form?
Figure showing the tectonic setting of earthquakes
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Earthquakes
Shaking of earth due to movement of rocks along a fault.Rocks under stress accumulate strain energy over time.When stress exceeds strength of rocks, rock breaks.Strain energy is released as seismic waves. The longer thatenergy is stored up and is maintained without release, themore likely that a strong earthquake will occur.
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Earthquakes are the manifestations of sudden release of strain energy
accumulated in the rocks over extensive periods of time
in the upper part of the Earth.
Seismology (derived from Greek word Seismos meaning
Earthquake and Logos meaning science) is the science ofEarthquakes and related phenomena
Aftershock
An earthquake that follows a large magnitude earthquake called,
main shock and originates in or around the rupture zone of the
main shock. Generally, major earthquakes are followed by a
number of aftershocks, which show a decreasing trend in
magnitude and frequency with time.
Seismograph/ Seismogram
Seismograph is an instrument that records the ground motions.
Seismogram is a continuous written record of an earthquake
recorded by a seismograph.
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Epicentre:
It is the point on the surface of the earth, vertically above
the place of origin (hypocentre) of an earthquake.
This point is expressed by its geographical Coordinates
in terms of latitude and longitude.
Hypocentre or Focus:
It is the point within the earth, from where seismic wavesoriginate. Focal depth is the vertical distance between
the Hypocentre (Focus) and Epicentre.
Magnitude:
It is a quantity to measure the size of an earthquake and is
independent of the place of the observation.
Intensity refers to the amount of damage done in an
earthquake and is dependent on the place of observation
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Tsunami
A system of gravity waves formed in the sea due to large
scale disturbance of sea level over a short duration of time.
Tsunamis are caused by earthquakes under the sea bottom,submarine volcanic eruptions, displacement of submarine
sediments, coastal landslides and meteor impact. However, not all
coastal earthquakes produce Tsunamis.
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Focus and Epicenter of Earthquake
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NATURE OF EARTHQUAKES
1) Foreshocks
2) Main shock
3) Aftershocks
4) Earthquake Swarm
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CLASSIFICATION DISTANCE
1) Teleseismic Earthquake > 1000 km2) Regional Earthquake > 500 km
3) Local Earthquake < 500 km
TYPES OF EARTHQUAKES
1) Tectonic Earthquake
2) Volcanic Earthquake
3) Collapse Earthquake
4) Explosion Earthquake
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Types of seismic waves1. Body waves -- travel through interior2. Surface waves -- travel on surface of earth
Specific Body WavesPrimary or "P" Waves: Primary waves Highest velocityCauses compression and expansion in direction of wave travel.Secondary or "S" Waves: Secondary or shear waves
Slower than P waves but faster than surface waves.Causes shearing of rock perpendicular to direction of wavepropagationCannot travel through liquids
Surface Waves or "Love" (L) WavesCause vertical & horizontal shakingTravel exclusively along surface of earth
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Primary or PWave
Secondary orS Wave
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Seismic Waves
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Time-Travel Curve
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Seismographs
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Seismogram Printout
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Determining the location of an earthquakeFirst, distance to earthquake is determined.1. Seismographsrecord seismic waves
2. From seismograph record called the seismogram, measure time delaybetween P & S wave arrival
3. Use travel time curve to determine distance to earthquake as functionof P-S time delay
Now we know distance waves traveled, but we don't know the direction fromwhich they came.
We must repeat the activity for each of at least three (3) stations totriangulate a point (epicenter of quake).
Plot a circle around seismograph location; radius of circle is the distance to thequake.
Quake occurred somewhere along that circle.
Do the same thing for at least 3 seismograph stations; circles intersect atepicenter. Thus, point is triangulated and epicenter is located.
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Triangulation of 3stations to locateearthquake
epicenter
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Earthquake Magnitude
M5
M6
M7
Magnitude-- measure of energy released duringearthquake.
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Richter Magnitude Scale
Distance S P Magnitude Amplitude
km sec ML mm
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Determining the magnitude of an earthquakeMagnitude-- measure of energy released during earthquake.There are several different ways to measure magnitude.Most common magnitude measure is Richter Magnitude, named for the
renowned seismologist, Charles Richter.
Richter Magnitude Measure amplitude of largest S wave on seismograph record. Take into account distance between seismograph & epicenter.
Richter Scale Logarithmic numerical (NOT a physical) scale Increasing one whole unit on Richter Scale represents 10 times greater
magnitude. Going up one whole unit on Richter Scale represents about a 30 times
greater release of energy.
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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. Using this scale, a
magnitude 5 earthquake would result in ten times the
level of ground shaking as a magnitude 4 earthquake(and 32 times as much energy would be released). A
magnitude 1 seismic wave releases as much energy
as blowing up 6 ounces of TNT. A magnitude 8
earthquake releases as much energy as detonating 6million tons of TNT.
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Earthquake Magnitude Scale
Magnitude Earthquake Effects Estimated Number
Each Year
2.5 or less
Usually not felt, but can
be recorded by
seismograph.
900,000
2.5 to 5.4Often felt, but only
causes minor damage.30,000
5.5 to 6.0Slight damage tobuildings and other
structures.
500
6.1 to 6.9
May cause a lot of
damage in very
populated areas.
100
7.0 to 7.9Major earthquake.
Serious damage.20
8.0 or greater
Great earthquake. Can
totally destroy
communities near the
epicenter.
One every 5 to 10 years
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Earthquake Magnitude Classes
Earthquakes are also classified in categories ranging from
minor to great, depending on their magnitude.
Class Magnitude
Great 8 or more
Major 7 - 7.9
Strong 6 - 6.9
Moderate 5 - 5.9
Light 4 - 4.9
Minor 3 -3.9
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EARTHQUAKE INTENSITY
Rossi-Forel Intensity Scale (I X)
Modified Mercalli (MM) Intensity Scale
(1956 version), (I XII)
Medvedev-Sponheuer-Karnik (MSK) Intensity Scale(1992 Version), (I XII)
Isoseismals
Isoseismals are the curved lines joining the localities of same intensity.
Intensity refers to the amount of damage done in anearthquakeMercalli Scale is used to express damage
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Magnitude / Intensity Comparison
Magnitude and Intensity measuredifferent characteristics of earthquakes.
Magnitude measures the energy released
at the source of the earthquake.
Magnitude is determined frommeasurements on seismographs.
Intensity measures the strength of
shaking produced by the earthquake at acertain location. Intensity is determined
from effects on people, human structures,
and the natural environment.
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Magnitude Typical Maximum
Modified Mercalli
Intensity
1.0 - 3.0 I
3.0 - 3.9 II - III
4.0 - 4.9 IV - V
5.0 - 5.9 VI - VII
6.0 - 6.9 VII - IX
7.0 and higher VIII or higher
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Abbreviated Modified Mercalli Intensity Scale
I. Not felt except by a very few under especially favorable conditions.
II. Felt only by a few persons at rest, especially on upper floors of
buildings.
III. Felt quite noticeably by persons indoors, especially on upper floors ofbuildings. Many people do not recognize it as an earthquake. Standing
motor cars may rock slightly. Vibrations similar to the passing of a truck.
Duration estimated.
IV. Felt indoors by many, outdoors by few during the day. At night, some
awakened. Dishes, windows, doors disturbed; walls make cracking sound.Sensation like heavy truck striking building. Standing motor cars rocked
noticeably.
V. Felt by nearly everyone; many awakened. Some dishes, windows
broken. Unstable objects overturned. Pendulum clocks may stop.
VI. Felt by all, many frightened. Some heavy furniture moved; a fewinstances of fallen plaster. Damage slight.
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VII. Damage negligible in buildings of good design and construction;
slight to moderate in well-built ordinary structures; considerable
damage in poorly built or badly designed structures; some chimneys
broken.VIII. Damage slight in specially designed structures; considerable
damage in ordinary substantial buildings with partial collapse. Damage
great in poorly built structures. Fall of chimneys, factory stacks,
columns, monuments, walls. Heavy furniture overturned.
IX. Damage considerable in specially designed structures; well-
designed frame structures thrown out of plumb. Damage great in
substantial buildings, with partial collapse. Buildings shifted off
foundations.
X. Some well-built wooden structures destroyed; most masonry and
frame structures destroyed with foundations. Rails bent.
XI. Few, if any (masonry) structures remain standing. Bridgesdestroyed. Rails bent greatly.
XII. Damage total. Lines of sight and level are distorted. Objects thrown
into the air.
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EARTHQUAKE ENERGY
log E = 12 + 1.8 ML
log E = 5.8 + 2.4mb
log E = 11.4 + 1.5Ms
1.0 10.0 times about 32 times0.5 3.2 times about 5.5 times
0.3 2.0 times about 3 times
0.1 1.3 times about 1.4 times
Magnitude Ground Motion Energy
Magnitude versus ground motion and ener
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the big one
A Magnitude 8 (M8)
earthquake is much bigger
than a M7 earthquake:
Roughly 10x greater
displacements
Roughly 30x more energy
released
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Bigger Faults Make Bigger Earthquakes
1
10
100
1000
5.5 6 6.5 7 7.5Magnitude
Kilometers
8
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Bigger Earthquakes Last a Longer Time
1
10
100
5.5 6 6.5 7 7.5 8
Magnitude
Second
s
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EARTHQUAKE MAGNITUDE FREQUENCY AND ENERGY
http://en.wikipedia.org/wiki/File:Graph_of_largest_earthquakes_1906-2005.png7/30/2019 Lecture 22 23
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EARTHQUAKE MAGNITUDE, FREQUENCY AND ENERGY
One of the largest earthquakes since seismometer invented ~ 1900
Stein & Wysession after IRIS
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LIST OF SOME SIGNIFICANT EARTHQUAKES IN INDIA
AND ITS NEIGHBOURHOOD
DATE EPICENTRE LOCATION MAGNITUDE
Lat (Deg.N)Lat
(Deg.E)
1819 JUN 16 23.6 68.6KUTCH,
GUJARAT8.0
1869 JAN 10 25 93
NEAR
CACHAR,
ASSAM
7.5
1885 MAY 30 34.1 74.6 SOPOR, J&K 7.0
1897 JUN 12 26 91SHILLONG
PLATEAU8.7
1905 APR 04 32.3 76.3 KANGRA,H.P
8.0
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1918 JUL 08 24.5 91.0SRIMANGAL,
ASSAM
7.6
1930 JUL 02 25.8 90.2DHUBRI,
ASSAM7.1
1934 JAN 15 26.6 86.8BIHAR-
NEPALBORDER8.3
1941 JUN 26 12.4 92.5ANDAMAN
ISLANDS8.1
1943 OCT 23 26.8 94.0 ASSAM 7.2
1950 AUG 15 28.5 96.7
ARUNACHAL
PRADESH-
CHINA BORDER
8.5
1956 JUL 21 23.3 70.0ANJAR,
GUJARAT7.0
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1967 DEC 10 17.37 73.75KOYNA,
MAHARASHTRA6.5
1975 JAN 19 32.38 78.49 KINNAUR, HP 6.2
1988 AUG 06 25.13 95.15
MANIPUR-
MYANMAR
BORDER
6.6
1988 AUG 21 26.72 86.63BIHAR-NEPAL
BORDER6.4
1991 OCT 20 30.75 78.86 Uttarakhasi, UP 6.6
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1993 SEP 30 18.07 76.62Latur/Killari
Maharashtra6.3
1997 MAY 22 23.08 80.06 Jabalpur, MP 6.0
1999 MAR 29 30.41 79.42Chamoli District,
UP6.8
2001 JAN 26 23.40 70.28 BHUJ , GUJARAT 7.7
2004 DEC 26 03.34 96.13OFF WEST COAST
OF SUMATRA9.3
2005 OCT 08 34.49 73.15 PAKISTAN 7.6
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Date Location Name Magnitude
0
May 22, 1960 Valdivia, Chile 1960 Valdiviaearthquake
9.5
March 27, 1964Prince William
Sound, Alaska, USA
1964 Alaska
earthquake9.2
December 26, 2004Indian Ocean,
Sumatra, Indonesia
2004 Indian Ocean
earthquake9.19.3
November 4, 1952Kamchatka, Russia
(then USSR)
1952 Kamchatka
earthquakes9.0
March 11, 2011
Pacific Ocean,
Thoku region,
Japan
2011 Thoku
earthquake9.0
November 25, 1833 Sumatra, Indonesia1833 Sumatra
earthquake8.89.2 (est.)
January 31, 1906Ecuador
Colombia
1906 Ecuador-
Colombia
earthquake
8.8
Large earthquakes of the World
http://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/Indian_Oceanhttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Kamchatkahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Pacific_Oceanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Ecuadorhttp://en.wikipedia.org/wiki/Colombiahttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/1906_Ecuador-Colombia_earthquakehttp://en.wikipedia.org/wiki/Colombiahttp://en.wikipedia.org/wiki/Ecuadorhttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/1833_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquakehttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Pacific_Oceanhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kamchatkahttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indian_Oceanhttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/1964_Alaska_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/Prince_William_Soundhttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1960_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valdivia,_Chile7/30/2019 Lecture 22 23
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February 27,
2010Maule, Chile
2010 Chile
earthquake8.8
January 26, 1700 Pacific Ocean,USA and Canada
1700 Cascadiaearthquake
8.79.2 (est.)
July 8, 1730 Valparaiso, Chile1730 Valparaiso
earthquake8.79.0 (est.)
November 1,
1755
Atlantic Ocean,
Lisbon, Portugal
1755 Lisbon
earthquake
8.7 (est.)
February 4, 1965Rat Islands,
Alaska, USA
1965 Rat Islands
earthquake8.7
July 9, 869
Pacific Ocean,
Thoku region,
Japan
869 Sanriku
earthquake8.6 (est.)
October 28,
1707
Pacific Ocean,
Shikoku region,
Japan
1707 Hei
earthquake8.6 (est.)
http://en.wikipedia.org/wiki/Maule_Regionhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/Valparaisohttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/Lisbonhttp://en.wikipedia.org/wiki/Portugalhttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/Rat_Islandshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Shikoku_regionhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquakehttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/Shikoku_regionhttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/869_Sanriku_earthquake_and_tsunamihttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/T%C5%8Dhoku_regionhttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/1965_Rat_Islands_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Rat_Islandshttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/1755_Lisbon_earthquakehttp://en.wikipedia.org/wiki/Portugalhttp://en.wikipedia.org/wiki/Lisbonhttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/1730_Valparaiso_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valparaisohttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/1700_Cascadia_earthquakehttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/2010_Chile_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Maule_Region7/30/2019 Lecture 22 23
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August 15, 1950
Assam, India
Tibet, China
1950 Medog
earthquake 8.6
March 9, 1957
Andreanof
Islands, Alaska,
USA
1957 Andreanof
Islands
earthquake
8.6
March 28, 2005Sumatra,
Indonesia
2005 Sumatra
earthquake8.6
August 13, 1868Arica, Chile
(then Peru)
1868 Arica
earthquake8.59.0 (est.)
December 16,
1575
Valdivia, Chile
(Kingdom of
Chile)
1575 Valdivia
earthquake8.5 (est.)
October 20,
1687
Lima, Peru
(Viceroyalty of
Peru)
1687 Peru
earthquake8.5 (est.)
http://en.wikipedia.org/wiki/Assamhttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Tibethttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Aricahttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Limahttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/1687_Peru_earthquakehttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Viceroyalty_of_Peruhttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Limahttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/1575_Valdivia_earthquakehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Valdivia,_Chilehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/1868_Arica_earthquakehttp://en.wikipedia.org/wiki/Peruhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Aricahttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/2005_Sumatra_earthquakehttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/1957_Andreanof_Islands_earthquakehttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Alaskahttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/Andreanof_Islandshttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/1950_Medog_earthquakehttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/Tibethttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Assam7/30/2019 Lecture 22 23
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May 24, 1751
Concepcin,
Chile (Kingdom
of Chile)
1751
Concepcin
earthquake
8.5 (est.)
November 11,
1922
Atacama
Region, Chile
1922 Vallenar
earthquake8.5
February 3,
1923
Kamchatka,
Russia (USSR)
1923 Kamchatka
earthquakes8.5
February 1,
1938
Banda Sea,Indonesia
(Dutch East
Indies)
1938 Banda Sea
earthquake8.5
October 13,
1963
Kuril Islands,
Russia (USSR)
1963 Kuril
Islandsearthquake
8.5
September 12,
2007
Sumatra,
Indonesia
2007 Sumatra
earthquakes8.5
http://en.wikipedia.org/wiki/Concepci%C3%B3n,_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/Kamchatka_Peninsulahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Banda_Seahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/Kuril_Islandshttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/September_2007_Sumatra_earthquakeshttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Sumatrahttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/1963_Kuril_Islands_earthquakehttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kuril_Islandshttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/1938_Banda_Sea_earthquakehttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Dutch_East_Indieshttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Banda_Seahttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Kamchatka_earthquakeshttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Kamchatka_Peninsulahttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/1922_Vallenar_earthquakehttp://en.wikipedia.org/wiki/Chilehttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/Atacama_Regionhttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/1751_Concepci%C3%B3n_earthquakehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Captaincy_General_of_Chilehttp://en.wikipedia.org/wiki/Concepci%C3%B3n,_Chile7/30/2019 Lecture 22 23
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Figure 1. Schematic views of Indian tectonics. Plate boundary velocities are indicated in mm/year. Shading indicates flexure of India: a 4 km deep trough near the Himalaya an
Isoseismal of the 2001 Bhuj
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Isoseismal of the 2001 Bhuj
Earthquake, Mw 7.7
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Isoseismals of large earthquakes in India
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The earthquake zoning map of India divides India into 4
seismic zones (Zone 2, 3, 4 and 5) unlike its previous
version which consisted of five or six zones for thecountry. According to the present zoning map, Zone 5
expects the highest level of seismicity whereas Zone 2 is
associated with the lowest level of seismicity.
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Zone 5
Zone 5 covers the areas with the highest risks zone that
suffers earthquakes of intensity MSK IX or greater. The
IS code assigns zone factor of 0.36 for Zone 5. Structural
designers use this factor for earthquake resistant design
of structures in Zone 5. The zone factor of 0.36 is
indicative of effective (zero period) peak horizontal
ground accelerations of 0.36 g (36 % of gravity) that maybe generated by an earthquake in this zone. It is referred
to as the Very High Damage Risk Zone. The state of
Kashmir, Punjab, the western and central Himalayas, the
North-East Indian region and the Rann of Kutch fall in
this zone.Generally, the areas having trap or basaltic rock are
prone to earthquakes.
Zone 4
http://en.wikipedia.org/wiki/MSK-IXhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Punjab_(India)http://en.wikipedia.org/wiki/Himalayashttp://en.wikipedia.org/wiki/Rann_of_Kutchhttp://en.wikipedia.org/wiki/Rann_of_Kutchhttp://en.wikipedia.org/wiki/Himalayashttp://en.wikipedia.org/wiki/Punjab_(India)http://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/Peak_ground_accelerationhttp://en.wikipedia.org/wiki/MSK-IX7/30/2019 Lecture 22 23
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Zone 4
This zone is called the High Damage Risk Zone and
covers areas liable to MSK VIII. The IS code assignszone factor of 0.24 for Zone 4. The Indo-Gangetic basin
and the capital of the country (Delhi), Jammu and Bihar
fall in Zone 4. In Maharashtra Patan area(Koyananager)
also in zone 4.
Zone 3
TheAndaman and Nicobar Islands, parts ofKashmir,
Western Himalayas fall under this zone. This zone isclassified as Moderate Damage Risk Zone which is
liable to MSK VII. and also 7.8 The IS code assigns
zone factor of 0.18 for Zone 3.
http://en.wikipedia.org/wiki/Andaman_and_Nicobar_Islandshttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Kashmirhttp://en.wikipedia.org/wiki/Andaman_and_Nicobar_Islands7/30/2019 Lecture 22 23
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Zone 2
This region is liable to MSK VI or less and is classified asthe Low Damage Risk Zone. The IS code assigns zone
factor of 0.10 (maximum horizontal acceleration that can
be experienced by a structure in this zone is 10 % of
gravitational acceleration) for Zone 2.
H ds ss i t d ith Q k s
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Hazards associated with Quakes Shaking:
Frequency of shaking differs for different seismic waves.High frequency body waves shake low buildings more.
Low frequency surface waves shake high buildings more.Intensity of shaking also depends on type of subsurface material.Unconsolidated materials amplify shaking more than rocks do.Fine-grained, sensitive materials can lose strength when shaken. They losestrength by liquefaction.Buildings respond differently to shaking depending on construction styles,materials
Wood -- more flexible, holds up wellEarthen materials -- very vulnerable to shaking.
Ground displacement:Ground surface may shift during an earthquake (esp. if focus is shallow).Vertical displacements of surface produce fault scarps.
Tsunamis (NOT tidal waves)
Tsunamis are huge waves generated by earthquakes undersea or belowcoastal areas.If earthquake displaces sea surface, wave is generated that can grow as itmoves over sea surface.
FiresUsually occurs from shifting of subsurface utilities (gas lines)
More reasonable assessment, based upon actual seismicity
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The Global Seismic Hazard Assessment Program (GSHAP), with the support
of the International Council of Scientific Unions (ICSU), and endorsed as a
demonstration program in the framework of the United Nations International
Decade for Natural Disaster Reduction (UN/IDNDR).
Earthquake Hazard Potential Map
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Parkfield, CA
Earthquake Capital of the World
q p
Ground Acceleration
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Seismologists usually define strong ground motion as the
strong earthquake shaking that occurs close to(less than about 50 km from) a causative fault.
The strength of the shaking involved in strong ground
motion usually overwhelms a seismometer, forcing the use of
accelerographs (or strong ground motion accelerometers)for recording.
Ground Acceleration
http://en.wikipedia.org/wiki/Seismologyhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Geologic_faulthttp://en.wikipedia.org/wiki/Seismometerhttp://en.wikipedia.org/wiki/Accelerographhttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Accelerographhttp://en.wikipedia.org/wiki/Seismometerhttp://en.wikipedia.org/wiki/Geologic_faulthttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Seismology7/30/2019 Lecture 22 23
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What Controls the Level of Shaking?
Magnitude
More energy released
Distance Shaking decays with distance
Local soils
amplify the shaking
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Intense ground shaking during large
earthquakes can damage or even cause failureof engineered structures such as buildings,
bridges, highways, and dams. Sustained strong
shaking can also trigger ground failures, such
as rock falls, landslides, earth flows andliquefaction. Strong motion seismology uses
special sensors, called accelerometers, to
record these large-amplitude ground motions
and the response of engineered structures tothese motions.
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Comparison of peak ground acceleration with the damage intensities and zone factors as
defined by IS 1893 : 2002
IS code seismic zone II III IV V
Perceived shaking Moderate Strong Very strong Severe
Potential damage Very light Light Moderate Moderate
heavy
Peak acceleration (%g) 3.99.2 9.218 1834 3465
Ground Acceleration of India
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Ground Acceleration of India
DAMAGE DEPENDS ON BUILDING TYPE
RESISTANT CONSTRUCTION REDUCES EARTHQUAKE RISKS
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0.2 gDamage
onset for
modern
buildings
RESISTANT CONSTRUCTION REDUCES EARTHQUAKE RISKS
Earthquakes don't kill people; buildings kill people." Coburn &Spence 1992
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Social Impacts
(impact on people)
Economic Impacts
(impact on
business in the
area)
Environmental
Impacts (impact
on the landscape)
Primary effects Death,
Homes destroyed,Services e.g. water
disrupted,
Transport systems
damaged
Businesses &
property destroyed,
Landscape
destroyed,
Secondary effects Diseases Looting,
Economic effect ofrestoring
businesses
Fires,
Tidal Waves,Landslides
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COMPLEX PLATE
BOUNDARY ZONE IN
SOUTHEAST ASIA
Northward motion of
India deforms all of
the region
Many small plates
(microplates) andblocks
Molnar & Tapponier, 1977
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Tsunami Movement: ~600 mph in deep water
~250 mph in medium depth water
~35 mph in shallow water
TSUNAMI - water wave generated by earthquake
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NY Times
Worlds Largest Earthquake: 1964 Anchorage, Alaska
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Registered 8.6 on Richter Scale
Tsunami Movement
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NOAA
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IN DEEP OCEAN tsunami has long wavelength, travels fast,
small amplitude - doesnt affect ships
AS IT APPROACHES SHORE, it slows. Since energy is
conserved, amplitude builds up - very damaging
TSUNAMI WARNING
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Because seismic waves travel much
faster (km/s) than tsunamis, rapid
analysis of seismograms can identify
earthquakes likely to cause major
tsunamis and predict when waves will
arrive
Deep ocean buoys can measure
wave heights, verify tsunami and
reduce false alarms
Earthquake Prediction
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Earthquake Prediction:
Precursory Events
Ex/ 1989 Loma Prieta
Earthquake
Soil Helium Variation
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Also: Resistivity, water pressure and well levels, geyser
activity, changes in seismicity
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Earthquake Prediction: Animal Behavior??
Another Approach: Forecasting
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Seismic Gap Hypothesis
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Short-Term Crustal Deformation Precursor
Mogi, 1984
Short-Term Electromagnetic Precursor
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Short Term Electromagnetic Precursor
Fraser-Smith, et al., 1990
Paleoseismology
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M >7 mean = 132 yr s = 105 yr
Estimated probability in 30 yrs 7-51%
Sieh et al., 1989Extend earthquake
history with geologic
record
FREQUENCY-MAGNITUDE RELATIONSHIP
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For New Madrid,combine instrumental
seismology with earlierdata to explore largeearthquake recurrence
Largepaleoearthquakes
occurred at~ 1450 and 900 AD(Magnitudes unknown)
Gives a M7 every
few thousand years.
Might NEVER get aM8 earthquake
Stein & Newman, 2004
?
Earthquake Cycle
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Periodic Time-predicatable Slip-predicatable
Shimazaki and Nakata, 1980
Earthquake Cycle
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Parkfield, California,
showed evidence of the
recurrence of similar-sized
(M 6.0) earthquakes
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In 1985 a 6.0 Parkfield earthquake was predicted with 95% confidence to
occur by 1993.
Mean = (1966-1857)/5 = 22 years
Expected date = 1988
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Didnt occur until 2004
(16 years late!)
Was it a success?
Right size, right location,wrong date.
Prediction of the 1975 Haicheng, China
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g
Earthquake (M7.3)
Prediction based on foreshocks
and animal behavior saved many
lives