Edexcel GCSE Geography B (1GB0) — Hazardous Earth
A magnitude 7.0 earthquake in one country can kill over 200,000 people, while a far stronger magnitude 9.0 earthquake elsewhere might directly kill fewer than 1,000. Why does a country's wealth drastically change the way the earth shakes?
The answer lies in how development influences a nation's ability to prepare for and respond to tectonic events. We assess the severity of these events by categorising their effects into primary impacts and secondary impacts.
In developed nations, strict building codes and aseismic design mean that direct deaths from shaking are often low. Instead, the highest costs come from secondary impacts and economic disruption.
In emerging and developing countries, poor infrastructure leads to catastrophic death tolls, and the economic damage represents a much larger percentage of their total wealth.
Volcanic eruptions are measured using the Volcanic Explosivity Index (VEI). Like earthquakes, the balance of primary and secondary impacts varies by development.
To fairly compare the impact of hazards across different countries, geographers calculate the economic loss as a percentage of the country's Gross Domestic Product (GDP).
Worked Example: Nepal 2015 Earthquake
Step 1: Identify the financial values from the disaster.
Step 2: Substitute these values into the equation.
Step 3: Calculate the final percentage.
When the ground stops shaking, the first thing many people do today isn't calling emergency services—it's posting online. Modern disaster assessment relies on three distinct types of data, each with unique strengths and critical limitations.
| Data Source | Primary Strength (Assess) | Main Weakness (Assess) |
|---|---|---|
| Social Media | Best for immediate, real-time response and saving lives in the "golden hour." | Biased and unreliable; excludes those on the wrong side of the "digital divide" (e.g. elderly or very poor). |
| Satellite Imagery | Best for mapping the spatial extent of damage in unreachable or remote areas. | Processing takes time, and cloud cover (like monsoon rains) can completely block views. |
| Socio-Economic Data | Vital for long-term planning and calculating the total "true cost" (GDP loss, unemployment). | Often outdated; it does NOT help emergency services in the first 72 hours of a disaster. |
1. Social Media (Short-term Response) Platforms like Twitter and Facebook provide real-time crowdsourcing to locate trapped survivors when traditional phone lines fail (as seen in Japan, 2011). In Nepal (2015), over 7,000 volunteers used social media to map 14,000 miles of roads for aid agencies, a process known as crisis mapping.
2. Satellite Imagery (Spatial Assessment) Satellites use remote sensing to provide "before and after" comparisons without putting geologists in danger. For example, the British Geological Survey (BGS) used satellites to map over 3,000 landslides in Nepal to find blocked remote villages.
3. Socio-Economic Data (Long-term Analysis) Governments layer satellite imagery over population density and wealth statistics using GIS (Geographic Information System) software. This identifies which communities are most vulnerable and require the most financial aid for long-term recovery.
Students often confuse primary and secondary impacts; remember that tsunamis, landslides, and fires are secondary impacts because they are triggered by the initial event, not the hazard itself.
For 8-mark 'Assess' questions comparing developed and developing countries, examiners expect you to explicitly weigh up significance; state clearly that developed nations face higher absolute economic costs, while developing nations face higher death tolls and GDP percentage losses.
When assessing data sources (Skill 10), always provide a balanced argument by contrasting the real-time speed of social media against its unreliability due to the 'digital divide'.
Primary impact
The immediate effects caused directly by the hazard, such as ground shaking, building collapse, or being hit by lava.
Secondary impact
Indirect effects that occur hours, days, or weeks later as a result of primary impacts, such as tsunamis, disease from contaminated water, or economic loss.
Aseismic design
Building construction techniques designed to withstand earthquake shaking and reduce primary impacts on property.
Liquefaction
A process where intense ground shaking causes water-saturated soil to lose its strength and behave like a liquid, causing buildings to sink or tilt.
Volcanic Explosivity Index (VEI)
A scale from 0 to 8 used to measure the explosiveness of volcanic eruptions based on the volume of ejected material and ash cloud height.
Disaster Risk Equation
A formula (Risk = [Hazard x Vulnerability] / Capacity) showing that a hazard's risk increases with high vulnerability and decreases with high coping capacity.
Crowdsourcing
Obtaining information or input for a task by enlisting a large number of people via the internet or social media.
Crisis mapping
The real-time gathering and analysis of data from social media and satellites to assist humanitarian response during a disaster.
Remote sensing
Collecting data about the Earth's surface from a distance, typically using satellites or aircraft, without making physical contact.
GIS (Geographic Information System)
A digital framework that layers different types of data, such as satellite imagery and socio-economic statistics, to identify spatial patterns and vulnerable areas.
Put your knowledge into practice — try past paper questions for Geography B
Primary impact
The immediate effects caused directly by the hazard, such as ground shaking, building collapse, or being hit by lava.
Secondary impact
Indirect effects that occur hours, days, or weeks later as a result of primary impacts, such as tsunamis, disease from contaminated water, or economic loss.
Aseismic design
Building construction techniques designed to withstand earthquake shaking and reduce primary impacts on property.
Liquefaction
A process where intense ground shaking causes water-saturated soil to lose its strength and behave like a liquid, causing buildings to sink or tilt.
Volcanic Explosivity Index (VEI)
A scale from 0 to 8 used to measure the explosiveness of volcanic eruptions based on the volume of ejected material and ash cloud height.
Disaster Risk Equation
A formula (Risk = [Hazard x Vulnerability] / Capacity) showing that a hazard's risk increases with high vulnerability and decreases with high coping capacity.
Crowdsourcing
Obtaining information or input for a task by enlisting a large number of people via the internet or social media.
Crisis mapping
The real-time gathering and analysis of data from social media and satellites to assist humanitarian response during a disaster.
Remote sensing
Collecting data about the Earth's surface from a distance, typically using satellites or aircraft, without making physical contact.
GIS (Geographic Information System)
A digital framework that layers different types of data, such as satellite imagery and socio-economic statistics, to identify spatial patterns and vulnerable areas.
