Causes: Tectonic hazards are primarily caused by the movement of Earth's tectonic plates. These plates are constantly in motion, and their interactions at plate boundaries – where they meet – can lead to earthquakes and volcanic eruptions.

• Convergent boundaries: Where plates collide, one may subduct beneath the other. This process generates intense pressure and friction, leading to earthquakes and often volcanic activity (e.g., the Andes Mountains).
• Divergent boundaries: Where plates move apart, magma rises from the mantle to fill the gap, creating new crust and often resulting in volcanic eruptions (e.g., the Mid-Atlantic Ridge).
• Transform boundaries: Where plates slide past each other horizontally, friction builds up, and sudden releases of energy cause earthquakes (e.g., the San Andreas Fault).

Effects: The effects of tectonic hazards are varied and can be devastating.

• Earthquakes: Ground shaking can cause buildings to collapse, landslides, and tsunamis (if the earthquake occurs under the ocean).
• Volcanoes: Eruptions release lava, ash, and gases, which can destroy property, contaminate water supplies, and cause respiratory problems. Pyroclastic flows are particularly dangerous.

Responses: A range of responses are used to mitigate the impacts of tectonic hazards.

• Prediction and early warning systems: Scientists are working to improve earthquake and volcanic prediction, and early warning systems can provide valuable time for evacuation.
• Building codes: Stricter building codes in earthquake-prone areas require structures to be more resilient to ground shaking.
• Land-use planning: Restricting development in high-risk areas (e.g., near active volcanoes or fault lines) can reduce vulnerability.
• Evacuation plans: Developing and practicing evacuation plans is crucial for minimizing casualties.
• Disaster relief: International aid and emergency services are essential for providing assistance to affected communities.

Coastlines are constantly being shaped by a variety of processes, broadly categorised as erosional and depositional. Erosion involves the wearing away and removal of coastal material. This can be caused by several factors:

• Wave Action: The constant impact of waves against the coastline is a major erosional force. Waves carry energy that can dislodge rocks and sediment.
• Abrasion: Waves carrying sand and pebbles act like sandpaper, grinding away at the coastline.
• Hydraulic Action: The force of water entering cracks and fissures in rocks can compress air, causing the rocks to break apart.
• Attrition: Rocks and pebbles carried by waves collide with each other, becoming smaller and smoother.

Deposition, conversely, involves the dropping of eroded material. This occurs when waves lose energy, often in sheltered bays or estuaries. Key processes include:

• Longshore Drift: The movement of sediment along the coastline, caused by waves approaching the shore at an angle.
• Spit Formation: The accumulation of sand and shingle extending from the land into the sea.
• Bay and Headland Formation: Differential erosion creates bays (sheltered indentations) and headlands (prominent rocky features).

Examples of erosion include the formation of cliffs through wave action and abrasion, and the creation of caves and arches through hydraulic action. Examples of deposition include the building of sand dunes along beaches and the formation of spits.

Deposition occurs when the river loses energy and is unable to carry its sediment load. This happens when the river's velocity decreases, for example, when it enters a wider valley or a flatter area. As the velocity decreases, the river drops its sediment.

Processes of deposition include:

• Gradual deposition: Sediment is deposited slowly and evenly over a large area.
• Rapid deposition: Sediment is deposited quickly, often in a concentrated area. This can occur after a flood event.

Factors influencing landform type:

• Load of sediment: A large sediment load will lead to deposition in areas of low velocity.
• Gradient of the river: A gentle gradient will result in deposition.
• Availability of space: If there is plenty of space, sediment will be deposited over a wider area.
• Type of sediment: The size and shape of the sediment will influence the type of landform formed. For example, large boulders will form a different landform than fine sand.

Landforms formed by deposition include:

• Alluvial fans: Formed where a river emerges from a confined valley onto a plain.
• Floodplains: Formed by the deposition of sediment during floods.
• Deltas: Formed where a river enters a lake or the sea.