Effects and Responses to Tectonic Hazards

How a tectonic hazard creates a chain of effects

A tectonic hazard can harm people, damage buildings and disrupt everyday life. Its effects are what happens because of the event; its responses are the actions people take to deal with those effects.

Primary effects happen directly because of the hazard. During an earthquake, ground shaking can collapse homes, injure or kill people, damage roads and break water, gas and electricity supplies. During a volcanic eruption, lava and ash can damage buildings and farmland, ashfall can bury crops, and ash in the atmosphere can ground aircraft.

Secondary effects follow from the initial damage. A broken gas main may start a fire; damaged water supplies may leave people without clean drinking water, increasing the risk of disease. Destroyed homes leave people homeless, while damaged roads can prevent rescuers and supplies from reaching them. Businesses may lose income while they are closed, and food shortages can push prices up.

The connection matters more than the delay. For example, ground shaking → broken gas main → fire links a primary effect to a secondary effect, even if the fire starts within minutes. Earthquakes can also trigger landslides and avalanches. During an eruption, melting snow and ice can cause flooding and lahars: flows of water mixed with volcanic debris.

Responding to the emergency and rebuilding afterwards

Immediate responses focus on saving lives and meeting urgent needs during the emergency and the following days or weeks. Search-and-rescue teams locate survivors; medical staff treat injuries; shelters, food and clean water support people whose homes have been destroyed. Evacuation and clearing debris can help people reach safety and allow aid to get through.

Long-term responses take place over months and years. They include rebuilding homes, schools and transport routes, restoring services and helping people return to work. Recovery may also involve stronger building regulations, earthquake drills and better emergency planning.

Some activities span both stages. Emergency road clearance may create a route for ambulances, whereas rebuilding the road properly is a longer-term task. The distinction is therefore about the purpose and timescale of the action, rather than a fixed cut-off date.

Nepal, April 2015: extensive losses and difficult access

Nepal is a landlocked country between India and China. In 2015, its GDP per capita was below US$1,000, and about 80% of its population lived in rural, often remote communities. These conditions are important because limited resources and difficult access can make emergency relief and rebuilding harder.

In April 2015, a magnitude 7.8 earthquake struck Nepal. Its epicentre was about 80 km north-west of Kathmandu, in the Gorkha district, and its focus was approximately 15 km deep. More than 300 aftershocks followed.

The primary effects included approximately 9,000 deaths and more than 20,000 injuries. Electricity and water supplies were cut, and around 7,000 schools and 1,000 health facilities were damaged or destroyed. Shops, offices and factories were also destroyed.

The secondary effects extended beyond the damaged buildings. Almost 3.5 million people were made homeless. Avalanches affected Mount Everest and the Langtang Valley, while landslides blocked roads and rivers. Blocked roads made reaching remote communities more difficult. Damage to workplaces prevented people from earning a living, and damage to temples and World Heritage sites contributed to lost tourist income. Total damage was estimated at US$7–10 billion, around 35% of Nepal's GDP: a substantial burden relative to the size of its economy.

For the immediate response, 90% of the Nepalese army was mobilised, and tent cities were established in Kathmandu. International assistance included search-and-rescue teams, medical staff, medicines, food, water and temporary shelters. Crisis mapping using geographical information systems helped coordinate the response. The Asian Development Bank provided a US$3 million emergency relief grant.

The long-term response included clearing landslides and repairing roads to restore access to rural communities, rebuilding schools, introducing earthquake drills and strengthening building codes and their enforcement. The Asian Development Bank provided US$200 million for rebuilding, and a new government task force was established to plan for future earthquakes.

Central Italy, August 2016: rapid mobilisation but serious local damage

Italy is a high-income country, with GDP per capita above US$31,000. On 24 August 2016, a magnitude 6.2 earthquake struck central Italy, with a shallow focus of about 4.4 km. More than 200 aftershocks occurred over the next couple of days.

Its primary effects included 296 deaths and severe building damage. More than half of all buildings in Amatrice were damaged or destroyed, and around 80% of buildings in its old town were affected. The school collapsed and the hospital was badly damaged. In the immediate area, around 90% of livestock barns and stalls were destroyed.

The secondary effects included landslides blocking roads, homelessness, psychological distress and reduced tourism. Damage to agricultural buildings also disrupted farmers' livelihoods. Italy's wealth did not prevent severe losses in the worst-hit communities.

The immediate response involved soldiers, firefighters, the Red Cross, helicopters and 70 rescue-dog teams reaching the worst-hit areas within hours. Patients were transferred from Amatrice to a nearby hospital in Rieti, and a temporary hospital was established in Amatrice. Tents were supplied for about 10,000 homeless people, with additional shelter in sports halls and community buildings. Mobile kitchens served around 1,000 meals a day.

Communication also supported rescue work. Emergency telephone lines were established, and residents were asked to remove their Wi-Fi passwords so rescue teams could connect more easily.

For the long-term response, the government promised to move homeless people into temporary accommodation within six months. A €42 million initiative, called Home Italy, aimed to rebuild homes in their previous style. Community and Red Cross fundraising supported recovery. Children attended classes in nearby towns, and a temporary school was built in Amatrice to restore education.

What the comparison tells us about wealth

Both earthquakes killed people, damaged buildings, triggered landslides and required emergency shelter. Both countries also needed longer-term rebuilding. The difference was not the presence or absence of damage, but its scale and the resources available to respond.

Nepal suffered far more deaths and homelessness. Damage equivalent to around 35% of GDP placed a major strain on its economy. Its remote rural settlements and blocked roads complicated access, while international teams and funding played an important role in relief and rebuilding.

Italy could rapidly mobilise a range of domestic emergency services and transfer patients to a nearby hospital. Its greater economic resources provided more capacity to fund emergency care and reconstruction. Nevertheless, the destruction in Amatrice shows that national wealth does not guarantee that every building or community is well protected.

This is not a controlled comparison of wealth alone. Nepal's earthquake had a greater magnitude, both earthquakes were shallow, and the places and buildings affected differed. A strong explanation therefore links wealth to response capacity and recovery resources while also recognising the importance of the physical event and local conditions.

Effects: direct or consequential?

• Primary: directly caused by the hazard — deaths, injuries, collapsed buildings, damaged roads and broken supplies.
• Secondary: follow from initial impacts — fires, homelessness, disease risk, disrupted aid and lost income.
• Earthquakes can trigger landslides and avalanches; eruptions can cause flooding and lahars.

Responses: emergency or recovery?

• Immediate, days–weeks: rescue, medical care, evacuation, shelter, food and water.
• Long-term, months–years: rebuilding, restoring livelihoods, stronger building codes and improved emergency planning.

Nepal, April 2015

• Lower-wealth example: GDP per capita below US$1,000; many remote rural communities.
• Magnitude 7.8; focus about 15 km deep.
• Approximately 9,000 deaths, over 20,000 injured, almost 3.5 million homeless.
• Landslides blocked roads; tourism and livelihoods suffered. Damage: US$7–10 billion, around 35% of GDP.
• Immediate: army mobilisation, international aid, Kathmandu tent cities.
• Long-term: roads and schools rebuilt, stronger building codes, drills; US$200 million from the Asian Development Bank for rebuilding.

Central Italy, 24 August 2016

• High-income example: GDP per capita above US$31,000.
• Magnitude 6.2; focus about 4.4 km deep.
• 296 deaths; over half of Amatrice's buildings damaged or destroyed; hospital badly damaged.
• Landslides, homelessness, psychological distress and reduced tourism.
• Immediate: rescuers within hours, patient transfers, temporary hospital and tents for about 10,000 people.
• Long-term: accommodation promise within six months, €42 million Home Italy initiative, temporary school.

Main comparison

Greater wealth can support rapid emergency mobilisation and finance recovery. Nepal faced a larger burden relative to its economy and difficult rural access. However, magnitude, depth and local building conditions also influence losses: wealth alone does not explain the contrast.