Earthquakes as Natural Disasters: Causes, Impacts and Risk Reduction

When the ground beneath our feet suddenly shifts, buildings collapse, lives are lost, and entire communities are forever changed. Earthquakes represent one of nature’s most powerful and unpredictable forces, capable of causing devastation within seconds. Understanding how these seismic events occur, their historical impact, and how we can reduce their catastrophic effects is essential for building safer, more resilient communities worldwide.

How earthquakes happen and the seismic waves they generate 🔗

Earthquakes occur when two blocks of the earth suddenly slip past one another along a fault, releasing energy that has been building up due to tectonic plate movements. The earth’s outer layer consists of massive puzzle pieces called tectonic plates that constantly move, sliding past, bumping into, or pulling away from each other. When these plates get stuck due to friction but continue to move, energy accumulates until the fault finally gives way, producing an earthquake.

The point below the earth’s surface where the earthquake begins is called the hypocenter, while the location directly above it on the surface is the epicenter. When an earthquake strikes, it generates several types of seismic waves that travel through and along the earth’s surface, each with distinct characteristics and destructive potential.

Primary waves (P-waves) 🔗

P-waves are compressional waves that move particles back and forth in the same direction the wave travels. These are the fastest seismic waves, traveling at speeds between 4-8 kilometers per second through the earth’s crust. Because of their speed, P-waves arrive first at seismic recording stations. They can travel through solids, liquids, and gases, making them detectable across vast distances. While P-waves generally don’t cause significant damage, they serve as an early warning signal that more destructive waves are coming.

Secondary waves (S-waves) 🔗

S-waves are shear waves that move the ground perpendicular to the direction of wave travel, creating a side-to-side or up-and-down motion. These waves travel slower than P-waves, typically at 2.5-4 kilometers per second, and can only move through solid materials. S-waves are more destructive than P-waves due to their larger amplitudes and the shearing motion they create in structures.

Surface waves (L-waves) 🔗

Surface waves travel along the earth’s surface rather than through its interior. These waves cause the most damage to structures because they have the strongest vibrations and stay concentrated near the surface where buildings and infrastructure exist. The two main types are Love waves, which create horizontal side-to-side motion, and Rayleigh waves, which produce a rolling, elliptical motion similar to ocean waves. Surface waves arrive after both P and S-waves but cause the majority of destruction during major earthquakes.

Devastating earthquakes that have shaped history 🔗

Throughout history, earthquakes have claimed millions of lives and reshaped entire regions. Understanding past earthquakes helps us prepare for future events and highlights the importance of disaster preparedness.

India’s major seismic disasters 🔗

India has experienced numerous catastrophic earthquakes due to its location at the collision zone of tectonic plates. The 1905 Kangra earthquake killed more than 20,000 people in Himachal Pradesh, destroying nearly 100,000 homes and marking one of the deadliest pre-independence disasters.

More recently, the 2001 Bhuj earthquake in Gujarat claimed between 17,000-20,000 lives on India’s Republic Day, destroying approximately 400,000 homes and damaging millions of structures. This earthquake measured 7.7 in magnitude and caused damage estimated at billions of dollars.

The Himalayan region has been particularly vulnerable. The 1991 Uttarkashi earthquake killed 768-2,000 people, while the 1999 Chamoli earthquake resulted in 103 deaths and affected over 2,000 villages across multiple districts. The 1993 Latur earthquake in Maharashtra was particularly devastating because it struck an area previously considered non-seismic, killing approximately 8,000 people when stone houses collapsed in rural villages.

Recent global earthquake catastrophes 🔗

The international community was shocked by the February 2023 Turkey-Syria earthquakes, which killed over 55,000 people across both nations. A magnitude 7.8 earthquake struck in the early morning hours, followed nine hours later by a magnitude 7.7 aftershock. The devastation was immense-over 230,000 buildings were damaged or destroyed in Turkey alone, and more than 2.7 million people were left homeless. This disaster became the deadliest earthquake in Turkey’s modern history and the fifth-deadliest earthquake of the 21st century.

On New Year’s Day 2024, Japan experienced the Noto Peninsula earthquake with a magnitude of 7.5. While the direct death toll was lower at approximately 240 people, the total casualties eventually reached 691 when including disaster-related deaths from conditions in evacuation centers, hypothermia, and delayed medical care. The earthquake damaged over 204,000 structures and displaced thousands of residents, demonstrating that even in earthquake-prepared nations, these disasters exact a heavy toll.

Reducing earthquake risks through preparedness and mitigation 🔗

While we cannot prevent earthquakes, we can significantly reduce their devastating impacts through comprehensive disaster risk reduction strategies implemented at various timeframes.

Immediate response measures 🔗

Short-term disaster risk reduction focuses on immediate preparedness and response activities. Families should create emergency plans, assemble earthquake kits with essential supplies, and practice “Drop, Cover, and Hold On” drills regularly. During an earthquake, the safest action is to drop to your hands and knees, take cover under a sturdy table or desk, and hold on until the shaking stops. Communities should establish search and rescue teams and coordinate emergency response protocols to save lives in the critical hours following an earthquake.

Medium-term retrofitting and awareness 🔗

Medium-term measures involve strengthening existing infrastructure and raising public awareness. Retrofitting weak structures to meet seismic standards can prevent building collapse during earthquakes. Seismic safety aims to prevent casualties by establishing techniques that minimize damage to constructions, including innovations in energy dissipation and seismic base isolation that detach buildings from their foundations.

Education and training programs help communities understand earthquake risks and appropriate responses. Regular earthquake drills, like the Great ShakeOut exercises, ensure that people know how to protect themselves when shaking begins. Community awareness campaigns about securing heavy furniture, storing emergency supplies, and identifying safe spots in buildings can save countless lives.

Long-term building codes and resilient infrastructure 🔗

The most effective long-term strategy involves enforcing strict building codes in high seismic risk zones and developing resilient infrastructure. Programs like the National Earthquake Hazards Reduction Program develop strategies and tools that can reduce adverse earthquake effects and promote implementation of protective measures among at-risk communities.

Modern building codes require structures to withstand specific levels of ground shaking based on regional seismic hazards. Construction techniques such as reinforced concrete frames, shear walls, and flexible foundations help buildings absorb and dissipate seismic energy rather than collapse. In regions like Chile and Japan, strict enforcement of seismic safety designs has resulted in buildings remaining standing during major earthquakes, saving thousands of lives.

Infrastructure planning must also account for earthquake risks. Critical facilities like hospitals, fire stations, and emergency operation centers should be built to higher standards to remain functional after earthquakes. Utilities including water, gas, and electrical systems need earthquake-resistant designs to prevent secondary disasters like fires and flooding.

What do you think? How prepared is your community for a potential earthquake? What steps could you take today to make your home and family safer in the event of seismic activity?

References

1. https://www.usgs.gov/programs/earthquake-hazards/science-earthquakes
2. https://www.britannica.com/video/rock-vibrations-Earth-earthquake-waves-P-surface/-218347
3. https://www.sciencelearn.org.nz/resources/340-seismic-waves
4. https://www.sms-tsunami-warning.com/pages/seismic-waves
5. https://www.walkthroughindia.com/walkthroughs/top-15-most-devastating-earthquakes-in-india/
6. https://www.gktoday.in/list-of-major-indian-earthquakes/
7. https://www.gktoday.in/earthquakes-in-india-seismic-zoning-and-major-quakes/
8. https://en.wikipedia.org/wiki/1999_Chamoli_earthquake
9. https://en.wikipedia.org/wiki/2023_Turkey%E2%80%93Syria_earthquakes
10. https://en.wikipedia.org/wiki/2024_Noto_earthquake
11. https://disasterphilanthropy.org/disasters/2024-japan-earthquake/
12. https://www.habitat.org/our-work/disaster-response/disaster-preparedness-homeowners/earthquakes
13. https://www.unesco.org/en/ipred/knowledge
14. https://www.fema.gov/emergency-managers/risk-management/earthquake/nehrp