earthquake hazard
TRANSCRIPT
Department of Earth SciencesKFUPM
Introduction to Seismology
Earthquake Hazard
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Ali [email protected].
sa
33° E 60° E
10° N
37°N
Previous Quiz
m
(3)
(1)
(2)
(1) Explain the physical meaning of above graph?(2) What you think might be a reason for observing
roll-off at lower (3) and higher (1) magnitudes.
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Log N
Natural hazards in time
Magnitude
Log
of f
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MagnitudeL
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f re
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terv
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
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Example: Seismicity of Stable Craton Cores (SCC) •Earthquake Catalogue Completeness for SCC •Magnitude Range for SCC •Magnitude-Frequency Plot for SCC •Worldwide rates of stable cratonic core seismicity
•African SCC seismicity •North American SCC seismicity •South American SCC Seismicity •Australian SCC Seismicity
•Seismicity of Canadian Stable Craton •Seismicity of Arabian Stable Craton
Previous LectureIn
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Spatial distribution of hazards
Principal earthquake zones and explosivevolcanoes
‘Ring of Fire’
S. E. Asia
CaribbeanMountSt. Helens1980
Montserrat1995-present
Toba 73ka
Pinatubo 1991
Tambora 1815
Aitapei1998
Alaska 1964
Northridge 1994Loma Prieta 1989
Chile 1960
Izmit 1999Lisbon1755
Tangshen1976
Tokyo 1923Kobe 1995
Tropical cyclone zones
Bhuj 2001
Taiwan 1999
Columbia 1999
Venezuela 2000Hurricane Mitch1999
GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
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Where do earthquakes occur?
Alaska 1964
Chile 1960
Tokyo 1923Kobe 1995
Turkey 1999Lisbon1755
The 20th C top ten
California1989 1994
Gujarat2001
Kashmir2005
Sumatra2004
GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
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SEISMIC HAZARD AND RISK
Earthquake quantificationSo far: how big?
ML, mb, Ms, Mw
how much damage? I, Io, I MSK, I MM
where?WWSSN, local networks, ISC
and now: when?earthquake prediction
how often?seismic or earthquake
hazard
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The probability of an earthquake occurring:•Specifically: the probability of an earthquake of magnitude m occurring or being exceeded
or•the probability of ground motion at level x occurring or being exceeded (where x = I, a, v or d)
Seismic hazard and Risk
Seismic risk $ RISK = HAZARD x VULNERABILITY x $ VALUE (Unesco)
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Earthquakes as a hazard
Estimated > 8 million killed in earthquakes during last millennium2 million deaths in 20th century1990-99 cost US$215 billionOver 40 countries are under threat from major destructive quakesOver 100 a year have potential for serious destruction (>M = 6)
Source: USGS
1,300,000 est2 – 2.9Very minor
130,000 est3 – 3.9Minor
13,000 est4 – 4.9Light
13195 – 5.9Moderate
1346 – 6.9Strong
177 – 7.9Major
18 and aboveGreat
ANNUAL AVERAGE
MAGNITUDE
1,300,000 est2 – 2.9Very minor
130,000 est3 – 3.9Minor
13,000 est4 – 4.9Light
13195 – 5.9Moderate
1346 – 6.9Strong
177 – 7.9Major
18 and aboveGreat
ANNUAL AVERAGE
MAGNITUDE
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Some notable earthquakes in history
Source: Hazard Research Center
Year Region Deaths Magnitude (Ms) 1556 China (Shensi) 830,000 - 1737 India (Calcutta) 300,000 1811 US (Missouri, New Madrid) several Mercalli intensity XI 1819 India (Kutch) 1,543 1906 US (California, San
Francisco) 700 8.25
1908 Italy (Messina) 120,000 7.5 1920 China (Kansu) 180,000 8.5 1923 Japan (Tokyo-Yokohama) 143,000 8.2 1960 Southern Chile > 3,000 8.5 1964 Alaska 131 8.6 1976 China (Tangshan) > 250,000 7.6
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Recent notable earthquakes
Year Region Deaths Magnitude (Ms) 1989 US/California (Loma Prieta) 63 7.0 1989 Newcastle (Australia) 13 5.6 1994 US/California (Northridge) 56 6.9 1995 Kobe (Japan) 5,400 6.9 1999 Izmit (Turkey) ~19,118 7.4 1999 Chi-chi (Taiwan) 3,400 7.6 1999 Athens (Greece) 110 5.9 2001 Gujarat (India) ~100,000? 7.6 2004 Niigata (Japan) 35 6.6 2004 Sumatra (Indonesia) 300,000? 9.15m
2005 Kashmir (Pakistan) ~ 80,000 7.6 Source: Hazard Research Center
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Yearly average of worldwide damage from natural disasters in the last three decades (data from Munich R)
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Geological hazards in context:loss events worldwide 2000
Windstorm38%
Others 26%
Earthquake & volcanic14%
Flood22%Total 851
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
Source
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
Source
Geological hazards in context III: economic losses worldwide 2000
Flood 53%Quake & volcanic 1%
Other 14%
Windstorm 32%Total US$ 31 bn
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
Source
Geological hazards in context IV: insured losses worldwide 2000
Windstorm 75%Other 4%
Flood 21%
Total US$ 8.3 bn
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
Source
WHAT ARE WE TRYING TO ACHIEVE?
Scientifically-study seismicity properties of earthquake sequences cumulative coseismic deformation maximum earthquakes
Socially- mitigate against earthquake losses•advise land-use planners•advise decision makers•advise insurers•advise earthquake engineers and constructors
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In general terms:
estimate hazard-forecasting, time distribution
zone or macrozone -space distributionmicrozone - local fluctuations
define design earthquakesselect time histories ( seismograms)what is the maximum earthquake?what is the maximum loading during EQ?What is the lifetime of structure?What is design spectra like?what is the maximum credible loading?
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Forecasting earthquakesForecasting is not prediction
less precise based upon analysis of earthquake return periods rather than identification of pre-cursor y signs
Active faults or fault segments do not rupture in a random manner
they have characteristic return periods (or at least return period envelopes)these reflect strain accumulation along the fault and the capacity of the fault to resist strain up to a given characteristic point - for that fault or fault segment
There are complications:Rupture will not occur according to a rigid timetable - there is a return period envelope rather than specific dateStrain may be released by one large quake or a number of smaller ones (e.g. Marmara Sea south of Istanbul)this has implications for risk assessment
GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
SourceIntr
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The Seismic Gap concept
Defined as an area in an earthquake-prone region where there has been a below average level of seismic energy releaseThe 1989 Loma Prieta quake filled a gap that had been aseismic since 1906 Other gaps exist in
Aleutian arc (Alaska)south of IstanbulTokyosouthern California
Istanbul seismic gap
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GEOL 3026/C471 GEOLOGICAL HAZARDS2005
Geological hazards in context II: fatalities worldwide 2000
Quake & volcano 4%
Total 9,270
Flood 67%Windstorm 15%
Other 14%
Source