Assoc. Prof. Dr. Wan Zuhairi Wan Yaacob

Program Geologi

UKM

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Bencana sebagai proses semulajadi

• Proses-proses semulajadi geologi:-– endogen & eksogen

• mengakibatkan kerosakan harta benda dankehilangan nyawa; punca:-– Manusia tinggal dekat dengan kawasan bencana– Perubahan guna tanah – perbandaran / pembalakan –

flooding / landslide

• Frequency (recurrence interval) vs magnitude (amount of energy released); inversely related– Large flood– Volcanic eruption– earthquake

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less frequent

Magnitude-frequency concept

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Inverse relationship between magnitude and frequency

Much of the work forming the earth surface is done by events of moderate magnitude and frequency

Small magnitude, high frequency

High magnitude, less frequency

Moderate magnitude, moderate frequency

High impact

Benefits of natural hazards• River flooding

– Nutrient to floodplains– Delivering sediment to beaches– Flushing pollutants

• Landslides– Forming dam – produce lakes

• Volcanic eruptions – Create new land (Hawaii)– Nutrient-rich volcanic ash

• Earthquakes– Fault gouge: groundwater barrier (subsurface dam)– Mountain building

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Death and damage by natural hazards

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H = high; M = medium; L = low

Geobencana aktif

(Bencana semulajadi)

geobencana pasif

(Bencana berkaitan dengan manusia )

Earthquake Landslide/slope failure

Volkano Subsidence

Hurricane (Ribut) Flooding

Tornadoes Erosion

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JENIS – JENIS GEOBENCANA

Hazardous events (Aswathanarayana, 1995)

Type of hazard Events

Natural: purely natural, not induced by humans

Large earthquake, volcanic eruptions, subsidence in karst areas, large river floods, landslides

Mixed: Natural in character but influenced by human action

Small earthquakes in a region of below ground disposal liquid wastes, landslides in developed areas, river floods in develop areas

Technological: generated by human action

Subsidence in subsurface mines; failure of a dam or nuclear power plant, WAR??

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JENIS GEOBENCANA DAN HUBUNGAN DENGAN SAIZ DAN KEPANTASAN

Kegagalancerun/amblesipantas

Tsunami

Puting beliung

Banjir kilat

Volkano

Gempa bumi

Hakisan tebing Gelinciran tanah Banjir

Hakisan

Perlodakan

Amblesi perlahan

Rayapan tanah

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Saiz bencana BESARkecil

ke

pa

nta

sa

nP

ER

LA

HA

NP

AN

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Nature’s Top Ten Most Destructive Forces

10. WATER (Waterfall)

9. GEYSER

8. LIGHTING & THUNDER

7. WILD FIRE

6. RAIN AND FLOODING

5. AVALANCHE

4. OCEAN (giant waves) – TSUNAMIS

3. SUPER WIND

2. EARTHQUAKE

1. SUPERVOLCANO

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10- 6 : Can be avoided and escaped

1-5 : Faster and very difficult to

escape

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–“You never run faster than the avalanche”

– “The white killer”

-“Silent killer”

-“Giant vacuum cleaner”

–“You never escape the ground moving beneath you”

-“The sleeping giant”

Yellowstone National Park

New ranking !!!??

• 1. Tsunami

• 2. Earthquake

• 3. Volcanic

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Disaster Prediction & Warning

• Location

• Probability of occurrence

• Precursor events

• Forecasting

• Warning

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Risk Assessment

• Risk of particular event = (probability of that event occur) x (consequence of the event)

• Consequence = damage to people, property, economic activity, public service, etc)

• Large earthquake: low probability but high consequence

• Acceptable risk

– Minimum risk that people can accept

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Human response to hazards

• Land-use planning– Avoid build on floodplains or active

landslides

• Insurance – Flood insurance – Earthquake insurance

• Evacuation– Need sufficient time to evacuate

• Disaster preparedness– Training – Artificial control of natural processes

• Retaining wall against landslide• Flood control – dams; levees; smart tunnel;

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Pertambahan penduduk dan peristiwageobencana

• Pertambahan pendudukmenyebabkan ramai terpaksa tinggalberdekatan dengan kawasanbencana

• Cth 1: Mexico City – 23 million in 2300km2

– City is built on ancient lake beds– September 1985; 7.8 magnitude;

10,000 killed

• Cth 2: Colombian volcano del Ruiz– 1845 – mudflow; killing 1000– 1985 – another mudflow; 21000 killed

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Colombian volcano del Ruiz

TAMMAT

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