Topic 2 : Tectonics Cluster

Plate tectonic theory

Explains Earth's internal structure and how forces drive global plate movements.

Convection currents

Hot softened mantle currents that drive the movement of tectonic plates.

Slab-pull force

Gravity-driven subduction of denser oceanic plates that drags the rest of the plate along.

Seafloor spreading

Process where magma rises through mid-ocean ridges to form new oceanic crusts.

Evidence from age of rocks

Younger rocks are found near mid-ocean ridges, while older rocks are further away.

Limited sediment accumulation

Older oceanic crusts are destroyed at trenches, making oceanic crusts younger than continental crusts.

Magnetic striping

Alternating stripes of rock on the seafloor with normal and reversed magnetic polarity.

Evidence from rock composition

Basalt forms oceanic crust and contains minerals influenced by Earth's magnetic field.

Divergent plate boundaries

Plates move away from each other, resulting in mid-ocean ridges and earthquakes.

Convergent plate boundaries

Plates move towards each other, leading to fold mountains and oceanic trenches.

Transform plate boundaries

Plates slide past each other, resulting in faults and earthquakes.

Tectonic processes of earthquakes

Stress builds up until it exceeds the fault's strength, releasing seismic waves.

Magnitude of earthquakes

Determined by the energy released during ground movement, recorded by seismometers.

Measuring earthquakes

The Richter Scale measures local magnitude, while the Moment Magnitude Scale measures larger earthquakes.

Tectonic processes of volcanic eruptions

Magma with dissolved gases is less dense and forces its way upward through the crust.

Magnitude of volcanic eruptions

Determined by the amount of dissolved gases and magma viscosity.

Measuring volcanic eruptions

The Volcanic Explosivity Index measures the explosivity of eruptions based on various factors.

Distribution of earthquakes

Concentrated along plate boundaries, especially at the Pacific Ring of Fire.

Distribution of volcanoes

Located near convergent and divergent boundaries, with hot spot volcanoes away from them.

Distribution of tectonic hazards

Most hazards are near plate boundaries, affecting areas beyond their geographic region.

Earthquake hazards

Include ground shaking and tsunamis, impacting ecosystems, properties, and human life.

Volcanic eruption hazards

Include tephra and lava flows, causing destruction and health threats.

Benefits of volcanic eruptions

Provide fertile soil and valuable minerals, and allow for geothermal energy and tourism.

Disaster risk management

Aims to prevent and manage disaster risks, strengthening community resilience.

Disaster risk and loss

Can have serious economic, social, and environmental consequences, hindering development.

Reducing disaster risks

Important for developing countries as a cost-effective investment in future loss prevention.

Tectonic disaster risk

Interaction between hazards and vulnerability, leading to potential loss of life and property.

Factors influencing earthquake risks

Include hazard nature, building quality, and population density.

Factors influencing volcanic eruption risks

Include magma composition, water availability, and human settlements.

Strengthening resilience

Essential for communities in hazard-prone zones to recover from disasters effectively.

Strategies for community resilience

Include land use planning, hazard-resistant designs, and preparedness measures.

Challenges in building resilience

Limited community resources and organizational capabilities for disaster response.

Disaster management

Involves planning and strategies for responding to and recovering from disasters.

Disaster management strategies

Include search and rescue, evacuation, and restoring living conditions post-disaster.

Challenges in disaster management

Include lack of resources and the need for stakeholder collaboration.