Layer

Temperature

and depth

Density and pressure

Composition

Division

State

Crust

Lowest and shallow

Lowest

Silica

Continental

Solid

Oceanic

Mantle

Higher and deeper

Higher

Fe + Mg

Uppermost

Solid

Asthenosphere

Plastic

Lower mantle

Solid

Core

Highest and deepest

Highest

Fe + Ni

Outer

Liquid

Inner

Solid

Divergent

S人人

Convergent

Mainly Circum-Pacific Belt // Alpine-Himalayan Belt

Transform

- North American Plate and Pacific Plate

- North American Plate & Caribbean Plate

- South American Plate & Scotia Plate

Layer

Divergent

Plate Boundary

Construtive

Force

Tensional

C-C

- Rift valley (eg. East African Rift): central block sinks

- Normal faults → hanging wall displaced downward

- Magma rises through lines of weakness / faults / cracks → lava is ejected → lava cools and solidifies → volcanoes / submarine volcanoes

→ volcanic island: volcanoes repeated eruption → submarine volcanoes rise above sea level

O-O

- Mid-oceanic ridge: magma rises through lines of weakness / faults / cracks → lava flows out → lava cools and solidifies to form mid-oceanic ridge → new crustal materials form at the gap → age of rock is younger near mid-oceanic ridge → transform fault connect each segment of mid-oceanic ridge

- Rift valley: same as above

- Block mountain: cracks dip toward each other → central block is left as a block mountain

- Submarine volcanoes // volcanic island // volcanic island arc: same as C-C (eg. Easter Island)

Internal Process

Faulting // volcanism

Layer

Convergent

Plate Boundary

Destrutive

Force

Compressional

C-C

- Fold mountains: sediment is compacted into sedimentary rocks → sedimentary rocks folded up due to compressional force for a long period of time → uplifted (eg. Himalayas)

- Reverse faults: hanging wall displaced upward

O-O

- Ocean trenches: denser plate subducts below the other plate → formed in subduction zone (eg. Java Trench)

- Volcanic island arc (eg. Islands of Indonesia)

- Volcanic islands // submarine volcanoes: subducted crust melts into magma → magma rises through lines of weakness → lava is ejected → lava cools and solidifies

→ volcanic island: volcanoes repeated eruption → submarine volcanoes rise above sea level

O-C

- Ocean trenches: same as above (eg. Peru-Chile Trench)

- Fold mountain: denser oceanic plate subducts below continental plate → subducted crust melts into magma → sedimentary rocks folded up due to compressional force for a long period of time → uplifted (eg. Andes)

- Volcanoes: same as above (eg. Mount Chimborazo)

Internal Process

Folding // faulting // volcanism

Layer

Transform

Plate Boundary

Conservative

Force

Shearing

C-C

- Transform faults (eg. San Andreas Fault)

O-O

O-C

Volcanism

Hot spots: continuous extrusion of lava above hot spot → volcano grows gradually above sea level → hot spot fixed in location while Pacific Plate moves NW → original volcano further from hot spot and becomes extinct → newer volcano formed at SE of extinct volcano

Internal Process

Faulting // volcanism

Earthquake

- (name of two plates) collide / diverge / slide past → compressional / tensional / shearing force is generated → plate movements → stress builds up → stress exceeds strength of rock → rock breaks and displaces along the fracture → energy moves up in seismic waves → shaking

- Frequently in convergent and transform boundaries

Tsunami

- (name of two plates) collide / diverge / slide past → compressional / tensional / shearing force is generated → release of immense energy → violent shaking → normal / reverse / strike-slip fault → vertical movement of a large area of ocean floor / water body → vertical displacement of rocks on sea bed → set off big wave that piles up near the shallow shore

- Frequently in convergent boundaries

Volcanic Eruption

- Subducted crust melts into magma → magma rises through lines of weakness → lava is ejected → lava cools and solidifies and forms volcanoes / submarine volcanoes

→ repeated eruptions make submarine volcanoes rise above sea level → volcanic island

- Frequently in convergent / divergent / hot spots

Monitoring / forecasting / warning systems

→ earthquake: analyze past records → use seismographs to measure seismic waves → rely on satellites to detect slight movements

→ tsunami: install open-sea tsunami buoys / ocean-bottom tsunami gauges (eg. Pacific Tsunami Warning Centre)

→ volcanic eruption: study of history and geological structure of volcano → predict occurrence of eruptions

Effective

- More time for evacuation

- Raise awareness and preparedness for hazards

Ineffective

- Low level of technology → unable to predict time / place / magnitude precisely

- Low input of capital → no maintenance

- Corruption → inefficient government

Hazard-proof designs

→ tsunami: reinforce with concrete / provide evacuation routes / build sea walls  or costal levees

Effective

Prevent collapse of buildings → lower casualties → less people buried under collapsed buildings // less disruption of transport system / communication system

Ineffective

- Low availability of capital

- Low availability of technology

- Corruption → difficult to enforce building laws

Land-use planning

Effective

- Help government plan and formulate policies → reduce impact of earthquakes

- Avoid building facilities with potential dangers

- Impose laws governing the height and structure of buildings

- Establish evacuation route with adequate road signs at the urban-planning stage

Ineffective

- Low accuracy of identifying high-risk areas

- Wrong decisions = more loss of life / properties

Education and drills → teach students what to do before / during / after hazard // hold regular drills for general public

Effective

- Increase people's awareness / preparedness

- Minimize potential losses

Ineffective

- People tend to forget unhappy experiences or hazards that happened long time ago

Rescue systems → well-trained and well-equipped rescue teams

Effective

- Higher number of lives saved

- Less people killed by disease / dirty water / starvation post-hazard

Ineffective

Rescue is delayed by buried roads / collapsed communication systems / corrupt management / political barriers in LDC

Disaster aid and insurance

Effective

- Lower property losses

- Strengthen equipment available for rescue work

- Help rebuild homes and economy

Ineffective

Corruption → inefficient government

Earthquake

Opportunties

- Attract scientists from all over the world to study mountain science

- Attract mountaineering experts to climb the earth's summit

- Favor development of tourism industry

- Provide job opportunities → higher income and better living standards for local people

- Enhance economy

Risks

- Injuries / loss of life / spread of diseases

Primary:

- Damage structures

- Kill and injure people

- Shock people and cause panic

- Damage power lines / gas / water pipes

Secondary:

- Breakdown of communication links / disruption of transport / damage hospitals / hinder relief work

- Collapse of dam → widespread flooding

- Fires

- Contaminate water supply → spread of diseases

- Trigger tsunamis

- Aftershocks → collapse of weakened structures

Tsunamis

Risks

- Coastal flooding → wash away beaches / uprooting of trees / sweep away heavy objects further inland → destruction of infrastructure

- Changes to coastline

- Disruption to local ecosystems

- Injuries / loss of life / spread of diseases

Volcanic eruption

Opportunties

- Favor development of tourism industry

- Favor development of geothermal power

Risks

- Injuries / loss of life / spread of diseases