Natural Hazards and Coastal Environments Overview

Characteristics of volcanoes

Openings in the Earth's crust releasing magma, gas, and ash.

Characteristics of earthquakes

Sudden shaking caused by energy release along faults or plate boundaries.

Distribution of volcanoes and earthquakes

Found at destructive, constructive, and conservative plate boundaries.

Measurement of volcanoes

Volcanic Explosivity Index (VEI).

Measurement of earthquakes

Richter scale (magnitude), Mercalli scale (intensity).

Causes of volcanic hazards at plate boundaries

Subduction at destructive boundaries and magma rising at constructive boundaries.

Causes of earthquake hazards at plate boundaries

• Friction and pressure build-up at destructive, constructive, or conservative plate boundaries, which is suddenly released as seismic energy.

Causes of hazards at hotspots

Mantle plumes create volcanoes away from plate boundaries (e.g., Hawaii).

Characteristics of tropical cyclones

Intense low-pressure systems with strong winds and heavy rain.

Distribution of tropical cyclones

5°-30° latitude, fueled by warm oceans.

Measurement of tropical cyclones

Saffir-Simpson scale (Categories 1-5).

Causes of tropical cyclone hazards

Warm ocean temperatures, low pressure, wind shear, Coriolis effect.

Why people live in hazard-prone areas

Economic opportunities, fertile soils, cultural ties, or lack of alternatives.

Vulnerability to natural hazards

Depends on physical, social, and economic factors.

Short-term impacts of hazards

Injuries, deaths, infrastructure damage.

Long-term impacts of hazards

Economic loss, rebuilding, Displacement

Preparing for earthquakes

Public education, emergency plans, building codes.

Warning and evacuation

Alerts and plans to move people to safety.

Earthquake-resistant building design

Flexible materials and reinforced structures.

Remote sensing

Satellites to detect and monitor hazards.

GIS

Mapping and analyzing hazard data for better planning.

Short-term responses

Emergency aid, temporary shelter, supplies.

Long-term planning

Hazard mapping, rebuilding, and risk assessment.

Hazard management in developed countries

Advanced technology and infrastructure.

Hazard management in developing countries

Limited resources and reliance on international aid.

Constructive waves

Build up beaches; low energy.

Destructive waves

Erode coastlines; high energy.

Erosion processes

Attrition (rock-on-rock), abrasion (rock scraping), hydraulic action (water force), solution (dissolving).

Transportation processes

Traction (rolling), saltation (bouncing), suspension (floating), solution (dissolved).

Longshore drift

Movement of sediment along a coast by waves.

Mechanical weathering

Breakdown of rocks by freeze-thaw or salt cracking.

Chemical weathering

Rocks dissolved by acidic rainwater (e.g., carbonation).

Biological weathering

Breakdown by plants (roots) or animals (burrowing).

Mass movement

Downslope movement of material (sliding, slumping, rockfall).

Concordant coastline

Rock layers parallel to the coast.

Discordant coastline

Rock layers perpendicular to the coast.

Vegetation on coasts

Stabilizes dunes and prevents erosion.

Human impacts on coasts

Tourism, industry, and coastal management.

Isostatic sea level change

Local land-level changes (e.g., glacial rebound).

Eustatic sea level change

Global water volume changes (e.g., melting ice).

Emergent landforms

Raised beaches, relic cliffs.

Submergent landforms

Rias (drowned valleys), fjords (drowned glacial valleys).

Differential Erosion

Where harder rock forms protruding headlands and softer rock is worn away to create bays.

Wave-cut platforms

Flat areas left as cliffs erode.

Caves, arches, stacks, stumps

Erosion processes form these features in sequence.

Beaches

Formed by deposited sand or shingle.

Spits and bars

Longshore drift deposits sand to form spits; bars close off bays.