Assoc. Prof. Dr. Wan Zuhairi Wan Yaacob Program Geologi UKMfrdaus/PenelusuranInformasi/File-Pdf/L5_STAG...Bencana sebagai proses semulajadi •Proses-proses semulajadi geologi:-–endogen
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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
TA
S
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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