Earthquakes are among nature's most powerful and unpredictable phenomena. Every year, the Earth experiences hundreds of thousands of earthquakes — most too small to feel, but some capable of catastrophic destruction. Understanding the science behind these events is the first step toward protecting yourself, your family, and your property.
This section covers the fundamental concepts of earthquake science, from the geological forces that cause earthquakes to the technologies we use to detect and measure them. Whether you're a homeowner assessing seismic risk, a student learning about plate tectonics, or simply curious about how the Earth works, these guides provide comprehensive, research-based information.
How Earthquakes Work
What Causes Earthquakes?
Earthquakes result from the sudden release of energy that has accumulated in the Earth's crust. This energy builds up as tectonic plates move and interact, creating stress along fault lines. When the stress exceeds the strength of the rocks, the fault slips and releases energy in the form of seismic waves.
What Causes Earthquakes: The Complete Guide explains the physics of earthquake generation, including plate tectonics, fault mechanics, and the earthquake cycle.
Types of Earthquakes
Not all earthquakes are created equal. Tectonic earthquakes (caused by fault movement) are the most common and destructive, but volcanic earthquakes, collapse earthquakes, and even human-induced earthquakes also occur. Each type has distinct characteristics and hazard profiles.
Types of Earthquakes Explained covers the full spectrum of seismic events and where they occur.
Earthquake Waves
When a fault ruptures, it generates three types of seismic waves that travel through the Earth at different speeds. P-waves arrive first and cause back-and-forth motion. S-waves follow and cause side-to-side shaking. Surface waves arrive last but often cause the most damage.
Earthquake Waves: P-Waves, S-Waves, and Surface Waves provides a detailed explanation of wave mechanics and how they affect buildings and infrastructure.
Measuring Earthquakes
Magnitude Scales
The size of an earthquake is measured using magnitude scales. The moment magnitude scale (Mw) has largely replaced the original Richter scale for scientific purposes, though both measure the energy released at the source. Each whole number increase represents approximately 32 times more energy.
Earthquake Magnitude Scale: Richter vs. Moment Magnitude explains how earthquakes are measured and what different magnitude levels mean for damage potential.
Epicenter and Depth
An earthquake's location is defined by its epicenter (the point on the surface directly above the rupture) and its depth (how far below the surface the rupture occurred). Shallow earthquakes generally cause more surface damage than deep ones of the same magnitude.
Earthquake Epicenter and Depth Explained covers how seismologists locate earthquakes and why depth matters for hazard assessment.
Seismology
Seismology is the scientific study of earthquakes and seismic waves. Modern seismologists use networks of sensitive instruments to detect earthquakes worldwide, map fault systems, and assess seismic hazards. The field has advanced dramatically since the first seismographs were developed in the late 1800s.
Introduction to Seismology provides an overview of the science, its history, and its practical applications.
Earthquake Effects and Hazards
Aftershocks
Large earthquakes are almost always followed by aftershocks — smaller earthquakes that occur as the crust adjusts to the stress changes caused by the mainshock. Aftershock sequences can last for months or even years, and some aftershocks can be large enough to cause additional damage.
Understanding Aftershocks explains aftershock patterns, how long they last, and how to stay safe during aftershock sequences.
Liquefaction
Liquefaction occurs when saturated, loose soil loses its strength during earthquake shaking and behaves like a liquid. This phenomenon can cause buildings to sink, tilt, or collapse, and is a major hazard in areas with sandy or silty soils near water.
Soil Liquefaction: Causes, Effects, and Mitigation covers the science of liquefaction and how to assess whether your property is at risk.
Earthquakes and Tsunamis
Large undersea earthquakes can displace massive volumes of water, generating tsunamis that travel across ocean basins at jet-aircraft speeds. When these waves reach shallow coastal waters, they slow down and pile up into devastating walls of water.
How Earthquakes Cause Tsunamis explains the connection between seismic events and tsunami generation.
Earthquake Prediction and Preparedness
Can We Predict Earthquakes?
Despite decades of research, reliable short-term earthquake prediction remains beyond our current capabilities. Seismologists can identify high-risk areas and estimate long-term probabilities, but they cannot predict exactly when or where the next earthquake will strike.
The Science of Earthquake Prediction examines what we know, what we don't know, and why prediction is so difficult.
Earthquake-Resistant Buildings
While we cannot prevent earthquakes, we can design buildings to withstand them. Modern earthquake engineering uses flexible foundations, reinforced structures, and energy-dissipating systems to protect buildings and their occupants during strong shaking.
How Earthquake-Proof Buildings Work explores the engineering principles that make structures more resilient.
Continue Learning
Understanding earthquake science empowers you to make better decisions about preparedness. After exploring these guides, continue to our Preparedness Section to learn practical steps for protecting your home and family, or visit our Fault Lines Guide to learn about specific earthquake hazards in your region.