Geography and Cartography

1. Cartography Fundamentals

a) Definition and Purpose

• Cartography: The study and practice of making geographical maps (from Greek chartis = map, graphein = write).
• Maps represent spatial information using symbols chosen by cartographers to depict features like political boundaries, economic zones, or geological formations.

b) Map Symbols and Key

• Symbols represent:
  • Areas: forests, countries, temperature zones (often coloured or shaded).
  • Lines: transport routes, rivers, borders.
  • Points: houses, mountain peaks.
• Every map includes a key (legend) explaining these symbols.

c) Scale

• Scale shows the ratio between map distance and real-world distance.
• Numerical scale example: 1:50,000 means 1 cm on the map = 50,000 cm (500 m) in reality.
• Graphic scale: a visual graduated bar indicating distances.
• Scale size:

  Scale Type	Example	Detail Level	Area Covered
  Large scale	1:25,000	Detailed	Smaller area
  Small scale	1:100,000	Less detailed	Larger area

d) Map Projections

• Maps are always distorted because the Earth is spherical and cannot be perfectly represented on a flat surface.
• Different projections distort size, shape, or distances differently.
• Example: Countries near poles appear larger than reality.
• Only a globe shows true proportions accurately.
• Common projections:
  • Mercator (1569): preserves angles, distorts size near poles.
  • Robinson (1963): balances size and shape distortions.

e) Geographic Coordinate System

• To locate places precisely, maps use a grid system of imaginary lines:
  • Parallels: horizontal lines parallel to the equator (0° latitude), measuring north-south position up to 90° at poles.
  • Meridians: vertical lines from pole to pole, measuring east-west position from the Prime Meridian (0° longitude) up to 180° east or west.
• Locations are given in degrees (°) of latitude and longitude.

f) Important Concepts to Remember

A map’s scale, symbols, and projection determine how accurately it represents the real world.

g) Examples of Coordinates (for practice)

• Cities and their latitude/longitude can be found in atlases (e.g., Nyon, Vancouver, Buenos Aires).
• Capitals can be identified by coordinates (e.g., 41°17′ S, 174°46′ E).

h) Practical Application

• Large scale maps (e.g., 1:50,000) show more details (roads, buildings) than small scale maps (e.g., 1:200,000).
• Comparing sizes of countries or regions requires understanding map scale and projection distortions.

This summary condenses the essentials of cartography: definitions, symbols, scales, projections, and coordinate systems, enabling efficient revision without re-reading the full course.

1. Map Elements

A map is a visual representation of an area, designed to communicate spatial information clearly. Key elements include:

• Title: Indicates the map’s subject or purpose.
• Legend (Key): Explains symbols, colors, and patterns used.
• Scale: Shows the relationship between distances on the map and real-world distances.
• Compass Rose: Indicates directions (usually North).
• Grid/Coordinates: Helps locate places precisely using latitude and longitude.
• Labels: Names of places, features, or important points.

These elements ensure the map is understandable and useful for its intended audience.

2. Map Scales

The scale of a map defines how much the real world has been reduced to fit on the map. It is crucial for measuring distances and understanding the level of detail.

Types of Scales:

Key points:

• A large scale map shows a smaller area with more detail (e.g., 1:10,000).
• A small scale map shows a larger area with less detail (e.g., 1:1,000,000).
• Always use the scale to convert map measurements to real-world distances.

3. Using Scales

To calculate real distance:

$$\text{Real distance} = \text{Map distance} \times \text{Scale factor}$$

Example: On a 1:50,000 map, 2 cm on the map equals 1 km in reality (2 cm × 50,000 cm = 100,000 cm = 1 km).

To remember: The scale tells you how much the Earth’s surface has been shrunk to fit the map, which is essential for accurate distance measurement and understanding map detail.

1. Map Projections and Coordinate Systems

a) Key Concepts of Earth's Illumination and Rotation

• Day and night result from Earth being illuminated on one half by the Sun, while the other half remains in shadow.
• Earth rotates from west to east, causing the Sun to appear to rise in the east and set in the west.
• At the Equinoxes (Vernal and Autumn), day and night are equal (12 hours each) worldwide; the Sun is directly overhead at the Equator.
• During the Winter Solstice (around Dec 21-22), the southern hemisphere tilts toward the Sun; the Sun is overhead at the Tropic of Capricorn.
  • The Antarctic Circle experiences 24 hours of daylight (midnight sun).
  • The Arctic Circle is in continuous darkness (polar night).

b) Time Zones and Legal Time

• Solar time varies continuously with longitude, making it impractical for daily use.
• The world is divided into 24 time zones, each roughly 15° of longitude wide, where legal time is uniform.
• Time zone borders often follow political boundaries for convenience.
• The Prime Meridian at Greenwich, London, defines Greenwich Mean Time (GMT), the reference for all time zones.
• Most clocks now use Coordinated Universal Time (UTC), based on atomic clocks and adjusted occasionally by a leap second to stay aligned with Earth's rotation.
• Traveling eastward across time zones requires setting clocks forward by one hour per zone.
• Crossing the International Date Line (in the Pacific Ocean) changes the calendar date by one day.

c) Historical Notes

• The first time zone system was introduced in 1847 by British railway companies using GMT.
• In 1879, Sandford Fleming proposed a global system of hourly time zones.

The Earth’s rotation causes the cycle of day and night, but legal time zones standardize time to simplify human activities worldwide.

1. Earth's Movements and Seasons

a) Time Zones and Standard Time

• Standard Time Zones: Adopted worldwide to unify local times based on fixed offsets from GMT (Greenwich Mean Time) or UTC (Coordinated Universal Time).
• Historical Adoption: Before standardization, countries used local observatory times. Nepal was the last to adopt a standard time (UTC+5:45) in 1986.
• Daylight Saving Time (DST): Clocks are advanced by one hour during spring to autumn to maximize daylight use. This practice is currently debated globally.

b) Internal Structure of the Earth

The Earth is composed of four main layers, each with distinct properties:

• The Earth's layers are arranged by density: heaviest elements in the core, lighter materials outward.

c) Physical Layers Related to Plate Tectonics

• Oceanic crust: ~5 km thick, mainly basalt.
• Continental crust: ~35 km thick, mainly granite.

The Earth's seasons result from its axial tilt and orbital movements, affecting sunlight distribution and daylight duration throughout the year.

1. Time Zones

Time zones are regions of the Earth divided by longitudes where the same standard time is used. They help coordinate time across different areas based on the Earth's rotation.

2. Key Concepts

• The Earth rotates 360° in 24 hours → it rotates 15° per hour.
• Each time zone generally spans 15° of longitude, corresponding to a 1-hour difference in local time.
• Time zones are centered on meridians spaced 15° apart, starting from the Prime Meridian (0° longitude) in Greenwich, England.
• Moving eastward, time increases by 1 hour per zone; moving westward, time decreases by 1 hour per zone.

3. International Date Line (IDL)

• Located roughly along the 180° longitude line, opposite the Prime Meridian.
• Crossing the IDL east to west → add one day.
• Crossing the IDL west to east → subtract one day.
• It ensures the calendar date stays consistent worldwide despite time zone changes.

4. Practical Implications

To remember: The Earth is divided into 24 time zones, each 15° apart, with time increasing by one hour every 15° eastward from the Prime Meridian. The International Date Line adjusts the calendar day to maintain global time consistency.

1. Formation of New Oceanic Crust

• Magma reaches the surface, cools rapidly, and solidifies into basaltic rock.
• Each eruption widens the ridge and adds new crust, causing the oceanic plate to grow over time.

2. Convergent Boundaries: Subduction

• Subduction occurs when two tectonic plates move toward each other and one is forced beneath the other.
• Oceanic plate vs. Continental plate:
  • The denser oceanic plate subducts beneath the continental plate.
  • Forms deep oceanic trenches and triggers intense geological activity.
  • The subducted plate melts in the asthenosphere, creating magma.
  • The continental plate is compressed and uplifted, forming mountain ranges (e.g., the Andes).
  • Magma rising through cracks causes volcanic activity.
• Oceanic plate vs. Oceanic plate:
  • The older, denser plate subducts beneath the younger one.
  • Creates island arcs (e.g., Aleutian Islands).

3. Convergent Boundaries: Continental Collision

• When two continental plates collide, neither subducts due to similar densities.
• The crust crumples and folds, forming extensive mountain ranges.
• Examples:
  • The Alps (African Plate vs. Eurasian Plate)
  • The Himalayas (Indian Plate vs. Eurasian Plate)
• Characterized by intense geological activity (earthquakes, mountain building) but less volcanic activity than subduction zones.

4. Transform Boundaries (Conservative or Strike-Slip)

• Plates slide past each other horizontally along fault lines (strike-slip faults).
• Frequent earthquakes occur due to tension buildup and release.
• Example: San Andreas Fault in California, which may cause southern California to drift northwest over millions of years.

5. Earthquakes

• Result from a sudden release of energy within the Earth's crust.
• Generate seismic waves traveling at 4 to 13 km/s.
• Occur at the surface or deep underground; about one million earthquakes per year globally.

a) Historical Example

• 1356 Basel Earthquake: magnitude ~7.1M, most significant in Central Europe.

b) Earthquake Risk in Switzerland

• Located near the Rhine Rift Valley, a fault zone between African and Eurasian plates.
• Regions at risk: Valais, Basel, Rhine Valley.
• Monitored by the Swiss Seismological Service.

6. Effects of Earthquakes

7. Tectonic Context of Earthquakes

8. Causes and Terminology

• Most earthquakes caused by rupture of geological faults or rift zones.
• Other causes: volcanic activity, landslides, mine explosions, nuclear tests.
• Focus: point within the Earth where an earthquake originates.

Key point: Subduction recycles oceanic crust at convergent boundaries, balancing crust creation at divergent boundaries.

1. Earthquake Terminology

• Hypocentre (focus): The point inside the Earth where an earthquake originates, usually less than 100 km deep but can reach up to 500 km.
• Epicentre: The point on the Earth's surface directly above the hypocentre.

2. Seismic Scales

Two main scales measure earthquakes:

Key point: Richter scale quantifies energy released; Mercalli scale describes earthquake impact on people and structures.

3. Earthquake Risk Zones

• Most earthquakes occur along tectonic plate boundaries, especially in the Pacific Ring of Fire, which:
  • Encircles the Pacific Ocean.
  • Contains 452 volcanoes and over 75% of the world's active/dormant volcanoes.
  • Experiences mostly shallow earthquakes (within tens of km depth).
• Intraplate earthquakes occur away from plate boundaries due to crustal deformation (slow distortion of Earth's crust).
  • Examples: 1811–1812 Arkansas (USA), 1976 Tangshan (China).
• Earthquakes can also happen near hot spots (e.g., Hawaii) where magma rises through the mantle.

4. Earthquake Preparedness and Risk Reduction

Effective strategies to reduce earthquake damage include:

• Public education and training: Teaching safe responses (e.g., "Drop, Cover, and Hold On").
• Urban planning: Avoid building near fault lines.
• Earthquake-resistant construction: Use of rubber base isolators, steel bracing, hydraulic shock absorbers.
• Securing utilities: Reinforce water pipes and power lines to prevent secondary disasters.

Note: Developed countries (MEDCs) like Japan and the USA have advanced prevention measures; less developed countries (LEDCs) often lack resources, leading to higher casualties and damage.

5. Earthquake Prediction

• Reliable prediction of earthquakes remains impossible despite research.
• Potential indicators studied include:
  • Ground deformation
  • Changes in groundwater levels
  • Magnetic/electric field fluctuations
  • Unusual animal behavior
• No consistent or scientifically reliable method exists to predict exact time, location, or magnitude.

> Earthquake prediction is currently not achievable; focus remains on preparedness and risk reduction.

1. Earthquake Forecasting and Early Warning

• Probabilistic forecasting estimates the likelihood of seismic activity in a region over time, based on historical and geological data.
• Some countries use early warning systems that detect weaker P waves before the stronger S waves, providing a warning from a few seconds up to a minute before the earthquake.

Early detection of P waves can alert populations before the more damaging S waves arrive.

2. Structure and Behavior of a Volcano

• A volcano consists of a magmatic chamber beneath the surface connected to the exterior by vertical conduits called chimneys.
• Ashes and lava accumulate around chimneys during eruptions.
• Pre-eruption signs include:
  • Slight ground shaking from magma movement.
  • Expansion of the volcano’s flanks causing surface deformation.
  • Increased volume, temperature, and change in composition of gases released.
• Eruption process: Pressure builds in the magmatic chamber until magma rises through chimneys; gases escape as magma ascends; molten rock is called lava once it reaches the surface.
• Eruptions end when magma supply is exhausted or pressure drops.
• Volcanoes can remain dormant or inactive for long periods.

3. Classification of Volcanic Eruptions

4. Volcano Classification by Tectonic Setting

Rift volcanoes produce new crust as mantle material rises through plate gaps, forming mid-ocean ridges or land volcanoes.

1. Subduction Volcanoes

• Location: Found in subduction zones where an oceanic plate sinks beneath a continental plate.
• Formation process: Oceanic crust melts under high temperature and pressure, mixing with magma and water-saturated sediments.
• Magma ascent: Magma rises through ~80 km of continental crust, becoming chemically complex and viscous.
• Lava type: Andesite, thick and sticky, causing potential blockage in volcanic conduits.
• Eruption style: Explosive due to high silica, water, and gas content; typical of Strombolian eruptions.
• Volcano type: Called stratovolcanoes or composite volcanoes, characterized by steep-sided cones formed by alternating layers of lava, ash, and debris.
• Example: Mount Saint Helens (USA).

2. Hot Spot Volcanoes

• Location: Occur within tectonic plates, not at boundaries.
• Formation: Caused by mantle plumes—columns of hot molten rock rising from deep Earth.
• Lava type: Basaltic, with low silica and gas content.
• Eruption style: Effusive, producing steady lava flows without violent explosions.
• Volcano type: Large shield volcanoes with broad, gently sloping shapes.
• Example: Hawaiian Islands.

3. Matter Ejected by Volcanoes

4. Other Volcanic Features

• Volcanic Plug: Hardened magma filling a volcano’s central vent; remains after erosion, often used for buildings.
• Fumarole: Openings emitting volcanic gases, often visible as water vapor clouds.
• Solfatara: Fumaroles emitting sulfurous gases with a rotten egg smell; leave yellow sulfur deposits.
• Geyser: Natural hot spring ejecting water and steam periodically due to underground magmatic heating.

Key point: Subduction volcanoes produce explosive eruptions with viscous andesite lava, while hot spot volcanoes produce effusive eruptions with fluid basaltic lava.

1. Tsunamis

A tsunami is a large sea wave caused primarily by underwater earthquakes that displace a significant volume of water. The term originates from Japanese.

a) Key Characteristics

• Triggering events: underwater earthquakes, volcanic eruptions, landslides.
• Wave behavior:
  • In deep water, waves are low and barely noticeable.
  • Near shallow coasts, waves can rise dramatically, up to 30 metres high.
• Speed: between 500 and 800 km/h.
• Warning signs: the sea often recedes dramatically before the wave arrives.
• Multiple waves can strike in succession, increasing danger.
• Tsunamis may strike hours after the triggering earthquake.

b) Travel Time Example

• A tsunami generated 1,000 km offshore can take about 2 hours to reach the coast.

2. Examples of Notable Tsunamis

> A tsunami is a series of powerful waves caused by sudden displacement of water, capable of traveling at jet speeds and causing massive coastal destruction hours after the triggering event.