Earthquakes destroy through a combination of violent ground shaking, structural collapse, and a chain of secondary disasters that can cause more damage than the shaking itself. A single event can level tens of thousands of buildings, trigger tsunamis and fires, and leave entire regions uninhabitable. The 2023 earthquakes in Turkey and Syria, for example, killed over 52,000 people, damaged nearly 242,000 buildings, and caused an estimated $34.2 billion in direct physical damage across eleven provinces home to 15 million people.
Ground Shaking and Soil Liquefaction
The most immediate source of destruction is the shaking itself. Seismic waves radiate outward from the earthquake’s origin, vibrating the ground violently enough to crack foundations, shatter glass, and topple walls. At the highest intensities, virtually all constructed works are damaged or destroyed, railroad rails bend and buckle, and large shearing cracks open in the ground.
But the ground doesn’t just shake. In certain soil conditions, it stops behaving like a solid altogether. This process, called liquefaction, happens when loose, water-saturated soil loses its rigidity during shaking. Normally, grains of sand or silt press against each other and support the weight of whatever sits on top. During an earthquake, the grains rearrange and compact, squeezing water trapped between them. That water pressure builds until it equals the weight of the soil above it, at which point the ground essentially becomes a heavy fluid. Buildings sink, tilt, or float out of position. Underground pipes and tanks can rise to the surface. The ground itself can spread laterally or slide downhill, dragging roads and infrastructure with it.
Recent research has shown that liquefaction can also occur under “drained” conditions, where water flows through the soil during shaking rather than being trapped in place. This means liquefaction can happen at surprisingly low levels of seismic energy and at greater distances from the earthquake’s epicenter than previously expected. The result is that areas once considered safe from liquefaction may still be vulnerable, and formerly inhabited zones have sometimes been permanently abandoned after liquefaction destroyed their foundations.
How Buildings Fail
Buildings rarely tip over in one piece during an earthquake. Instead, they come apart. The most common and deadly failure pattern is “pancaking,” where floors collapse downward onto each other, stacking like a deck of cards. This is what kills the most people: occupants are trapped between slabs of concrete with no survivable space.
A particularly dangerous design flaw is the soft first story, where a building’s ground level is open (think parking garages, storefronts with large glass windows, or columns supporting apartments above). That open level is weaker and more flexible than the rigid floors above it, so it absorbs all the lateral movement and gives way first, dropping the rest of the building straight down. A similar problem occurs when internal support walls don’t line up from floor to floor, creating weak levels that buckle under lateral force. In the 2023 Turkey earthquakes, about 26% of affected buildings were either heavily damaged, collapsed, or required urgent demolition.
Tsunamis Triggered by Undersea Quakes
When an earthquake occurs beneath the ocean floor at a depth of less than about 100 kilometers (62 miles), the sudden vertical displacement of the seabed pushes an enormous volume of water upward, generating a tsunami. Most tsunami-producing earthquakes exceed magnitude 7.0, but a quake generally needs to reach magnitude 8.0 or higher to send a dangerous tsunami across an entire ocean basin.
In deep water, a tsunami wave may be barely noticeable, traveling at the speed of a jet airliner. As it approaches shore and the water becomes shallow, the wave compresses, slows, and grows dramatically in height. The destruction comes not just from the initial wave impact but from the powerful surge of water that floods inland, carrying debris, vehicles, and collapsed structures with it. The retreating water is equally dangerous, dragging everything back out to sea.
Fires After the Shaking Stops
Post-earthquake fires are one of the most underestimated sources of destruction. Ruptured natural gas lines account for 20% to 50% of all fire ignitions after an earthquake. Electrical short circuits caused by shaking are another major trigger, and they carry a delayed risk: when utility companies restore power to a damaged area, previously harmless short circuits suddenly become energized and can spark fires. Wood-framed buildings are especially vulnerable because a spark from a short circuit is far more likely to ignite wood than other building materials.
What makes these fires so destructive is that the normal firefighting response is crippled at exactly the moment it’s needed most. Water mains break during the shaking, fire stations may be damaged, roads are blocked by rubble, and emergency services are overwhelmed by rescue operations. Small fires that would normally be contained quickly can spread unchecked through entire neighborhoods.
Crush Injuries and Medical Emergencies
The leading cause of death in earthquakes is building collapse, and for those who survive the initial impact, the danger isn’t over. People trapped under rubble for extended periods often develop crush syndrome, a life-threatening condition that occurs when sustained pressure on muscle tissue causes the muscle cells to break down and release their contents into the bloodstream. When the person is finally freed and blood flow returns to the crushed limbs, those toxic byproducts flood the kidneys and other organs.
The primary killer in crush syndrome is acute kidney failure. The flood of muscle proteins overwhelms the kidneys, shutting them down. Dangerous spikes in potassium levels can cause heart failure. Survivors often require emergency dialysis, and those who arrive at hospitals with low blood pressure face significantly higher mortality. In mass casualty earthquakes, the sheer number of crush syndrome patients can overwhelm even well-prepared medical systems, because dialysis machines and the specialized care these patients need are always in limited supply.
Landslides and Ground Failures
Earthquakes destabilize slopes that may have been marginally stable for decades. Hillsides, cliff faces, and mountain terrain can give way during or immediately after shaking, burying roads, homes, and entire villages. Liquefaction-driven lateral spreading can cause riverbanks to slump and flat ground near slopes to shift horizontally. At the highest earthquake intensities, massive rockfalls and landslides reshape the landscape itself, damming rivers (which can later burst and cause flooding) and severing transportation routes that communities depend on for evacuation and aid delivery.
What Actually Reduces the Damage
The destruction earthquakes cause is not inevitable. Seismic retrofitting of existing buildings returns $13 in avoided losses for every $1 spent, according to a nationwide analysis by the National Institute of Building Sciences. Fixing soft-story buildings specifically returns $12 per dollar. Even simple, inexpensive measures make a difference: strapping water heaters to the wall returns $24 for every dollar invested, largely because unsecured water heaters are a major source of post-earthquake fires when they topple and rupture gas connections. Latching kitchen cabinets returns $8 per dollar by preventing falling objects from causing injuries and blocking escape routes.
On a larger scale, modern building codes that require structures to flex rather than fracture during shaking dramatically reduce pancake collapses. Countries and cities that enforce these codes consistently see far lower death tolls from comparable earthquakes. The difference between a magnitude 7.0 earthquake that kills dozens and one that kills tens of thousands often comes down to how the buildings were constructed, not how strong the shaking was.