Natural Hazards [email protected] Presentation on line at:...

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Natural HazardsNatural Hazards

[email protected]

Presentation on line at: www.geophysik.uni-muenchen.de/~malservisi/classes/NaturalHazards.htm

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Class schedule:

OCTOBER NOVEMBER DECEMBER JANUARY FEBRUARYmon 16 1tue 17 2wed 18 1 3thu 19 2 4 1fri 20 3 1 5 2sat 21 4 2 6 3sun 22 5 3 7 4mon 23 6 4 8 5tue 24 7 5 9 6wed 25 8 6 10 7thu 26 9 7 11 8fri 27 10 8 12 9sat 28 11 9 13 10

sun 29 12 10 14mon 30 13 11 15tue 31 14 12 16

wed 15 13 17thu 16 14 18fri 17 15 19sat 18 16 20sun 19 17 21mon 20 18 22tue 21 19 23wed 22 20 24thu 23 21 25fri 24 22 26sat 25 23 27sun 26 24 28mon 27 25 29tue 28 26 30wed 29 27 31

thu 30 28

fri 29sat 30sun 31

day room thema 13.12 AGU18.1 TU 0714 Intro 18.12 LMU 406 Volcanoes23.1 LMU 406 Intro Energy 20.12 TU 0714 Tsunami Lab 225.1 TU 0714 plate tectonics 25.12 Xmas30.1 LMU 406 Earthquakes Lab 1 27.12 Xmas1.11 national holiday 1.1 Xmas6.11 rocco in BC 3.1 Xmas8.11 rocco in BC 8.1 LMU 406 Tsunami Lab 2 due day

13.11 rocco in BC 10.1 TU 0714 Mass Movement Lab 315.11 rocco in BC 15.1 LMU 406 Mass Movements20.11 LMU 406 Earthquakes 17.1 TU 0714 Atmospheric engine22.11 TU 0714 Earthquakes 22.1 LMU 406 storm27.11 rocco in Berlin 24.1 TU 0714 hurricanes Lab 3 due day29.11 TU 0714 Earthquakes Lab 1 Due day 29.1 LMU 406 hurricanes4.12 LMU 406 Volcanoes 31.1 TU 0714 flood6.12 TU 0714 Volcanoes 5.2 LMU 406 flood

11.12 AGU 7.2 TU 0714 summary

A Definition:

HAZARD

A natural Hazard exist where a natural event is likely to harm people or properties

Another useful definition:

RISK:

The Probability that an events can occur in a given time X

the damage that the occurrence would cause

Not all the events are equals Not all the events are equals Hazard vs RiskHazard vs Risk



Largest earthquake in the 90s:

Magnitude 8.4 Balleny Islands Region 1998 March 25 03:12:25 UTC

NO SIGNIFICANT DAMAGES

NO CASUALTIES

Not all the events are equalsNot all the events are equalsHazards vs RiskHazards vs RiskSame year 1998:

Magnitude 5.5 Afghanistan-Tajikistan Border Region 1998 February 04 14:33:21 UTC





At least 2323 people killed8094 houses destroyed6725 livestock killed

Hazards vs RisksHazards vs RisksHazard: the potential to cause harm

Risk: the likelihood of harm in defined circumstances

Example:

Balleny Island potentially High seismic hazard Low seismic riskIf you build something there has the potential to be damagedbut since there is nothing the likelihood to be damaged is low.

Afghanistan High seismic hazard High seismic riskThe probability of earthquakes is high and the building in the Region are not built to resist an earthquake so it is very likely That a seismic event can make lot of damages.

Frequency vs MagnitudeFrequency vs MagnitudeIn general the Magnitude of an event is inversely proportionalto its Frequency to a given power. This says that normally the two variable are linear in a log log scale. Es for earthquakes:

The damage is not always related to large events.

Often lot of moderate events can do more damage than a big one.

Example of destroying a forest:

Termites are many and works continuously but in typical conditions do not destroy a full forest

Humans are fewer and work less often but cutting few trees at the time they can finish a forest (e.g. Iceland in middle age)

Elephant destroy lot of tree in one time but they are so few in a forest that their damages can be easily recovered.

The problem is when the large event became frequents (now the men destroy more than an elephant!)

Biggest risk?

Extraterrestrial Impact!!!

Can we change the hazard or the risk?

Let’s take for example a volcano:

Can we change the hazard? Or in other words can we stop the eruption?

But we can reduce the risk if we do not build our citiesOn the lahar path or too close to the volcano!!

MITIGATION

So what can we do?? So what can we do?? MITIGATIONMITIGATION

• Predictable or not?

• Preparedness and education

• Prevention vs reaction

Predictable vs UnpredictablePredictable vs Unpredictable







Hurricane are predictable with fewDays of warning

Images from Hurricane Ivan 2004






People can evacuate:Lot of damages but few casualty:Hurricane Andrew in 1992 is one of the worst disaster of US as total damages (250000 homeless 82000 business destroyed) but “only” 23 death

Preparedness and planningCan reduce the amount of damages

Predictable vs UnpredictablePredictable vs UnpredictableEarthquake can not be predicted but we know the regions where they can occur






Region where earthquake emergency are planned

Niigata, Japan, 1964 Mb 7.528 lives lost



And where they are not

Irpinia, Italy, 1980 Mb 6.94689 lives lost

So we can plan it with building that can resist the ground shaking“earthquakes do not kill, buildings do it”

Prediction ExamplesPrediction ExamplesHurricane prediction:Meteo observations and numerical modelcan help the forecast the evolution of a tropical storm up to 5 days in advance. Local storm and Tornado can not be forecasted.

Few days to few hours. Short term evacuation.



Meteorology, Climatology, Oceanography, Remote Sensing

• Seismic Activities: Earthquakes as precursors

• Thermal, magnetic and hydrologic conditions

• Amount of volcanic gas emission

• Topographic monitoring: Tilting and special bulging

• Remote sensing: Radar 3-D interferometry

• Geologic history of a volcano

Forecasting Volcanic Forecasting Volcanic ActivityActivity

Prediction ExamplesPrediction Examples

Volcanology, Geology, Geophysics, Remote Sensing

Volcanoes prediction:

Geological study let us know the past history of the volcano and its typical behavior (explosive or not, lahars path, etc…)

Geodetic observation monitor the deformation of the volcano.

Seismology give us the position of magma reservoir and magma movement.

Geochemical monitoring give us clues about the evolution of magma

These observations give as a day to day vital signs of the activity and allow to indicate the probability of an event

Mount Etna InSardeformation before eruption.

USGSMeasuring CO2At Long ValleyCalifornia

The forecasters can predict the probabilityof the event from few months to few hours before it happens. It can be necessary to have long term evacuation

Good example of MitigationGood example of Mitigation

Study of the hazard:

• Location

• Probability of occurrence

• Precursor

• Forecast

• Warning

Good example of MitigationGood example of Mitigation

Study of the hazard:

• Location

• Probability of occurrence

• Precursor

• Forecast

• Warning

ALL THIS CAN WORK ONLY IF

WE HAVE

• PLANNING

• PREPAREDNESS

• EDUCATION

These things are easier in richer countries!

Natural Processes soNatural Processes sowhere the energy came from?where the energy came from?Which processes are involved Which processes are involved

in Natural Hazards?in Natural Hazards?

For hazards associated with geological processes the“fight” between gravity and heat flow is the major playerthus plate tectonic, an effect of this “fight” is the theory

At the base of hazards related to earthquakes and volcanoes

Importance of time and speed

Importance of connectivity among different hazards

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