Blind thrust earthquake — Safekipedia Discoverer

A blind thrust earthquake occurs along a thrust fault that does not show signs on the Earth's surface, which is why it is called "blind." These faults cannot be seen or mapped by looking at the ground, making them hard to study until an earthquake happens. Sometimes, scientists discover these hidden faults while looking for oil or studying seismology.

Even though blind thrust earthquakes are not usually the strongest, they can be very dangerous. This is because they often happen near cities, where buildings and infrastructure can be heavily affected. This makes them important for understanding urban seismic risk.

Blind thrust earthquakes are similar to buried rupture earthquakes, which also leave few clues on the surface. Both types can surprise us because we cannot see the faults clearly until after the earthquake strikes.

Blind thrust faults

Diagram of blind-thrust faulting

Blind thrust faults are special types of cracks in the Earth’s crust that are hard to see because they don’t show on the surface. They usually form near places where huge pieces of the Earth’s crust, called tectonic plates, push against each other. When these plates press together, they can create overlapping sections of rock that look like hills and valleys from above.

Over time, weather and water can wear down these hills and fill in the valleys, making the land look flat. People often live in these flat areas because the soil is rich and good for farming. Even though these faults break apart occasionally, big earthquakes only happen every few hundred years. These earthquakes can be very damaging because the soft soil in the valleys can make the shaking feel much stronger.

Examples of occurrence

Los Angeles, California, has many earthquakes and researchers have found blind-thrust faults beneath the city. Studies using satellite data and GPS have shown that these hidden faults could cause significant earthquakes.

Several notable earthquakes have occurred on blind-thrust faults, including events in Turkey, Macedonia, California, Haiti, the Philippines, Nepal, and Morocco. These earthquakes remind us of the importance of understanding hidden faults to better prepare for future seismic events.

Main article: 1994 Northridge earthquake