Reverse (Thrust) Fault
Definition
A fault where the hanging wall moves upward relative to the footwall, caused by compressional forces. Thrust faults at shallow angles are responsible for the largest earthquakes.
Example
The 2011 Tohoku M9.1 earthquake ruptured a 500 km thrust fault off Japan's coast.
Related Terms
Related Guides
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Related Case Studies
The 2008 Sichuan Earthquake: 87,000 Dead Along the Longmenshan Fault
The earthquake that forced China to confront endemic building code violations after thousands of 'tofu-dreg' school buildings collapsed while adjacent government structures survived, killing over 5,000 children.
The 2005 Kashmir Earthquake: 87,000 Dead in the Himalayan Frontier
The deadliest Himalayan earthquake in modern history, which killed 17,000 students in collapsed schools and demonstrated the extreme difficulty of disaster response in remote mountainous terrain.
The 1999 Chi-Chi Earthquake: The Best-Recorded Near-Fault Earthquake in History
The best-instrumentally-recorded large earthquake in history, with 441 strong-motion stations capturing near-fault data that fundamentally changed how engineers design buildings close to active faults.
The 1976 Tangshan Earthquake: The Deadliest Earthquake of the 20th Century
The deadliest earthquake of the 20th century, which destroyed 93% of an industrial city in seconds and exposed the limitations of earthquake prediction despite China's success at Haicheng one year earlier.
The 1948 Ashgabat Earthquake: The Soviet Catastrophe That Was Hidden for Decades
The most concealed earthquake disaster in history, where the Soviet government classified the true death toll of 110,000 as a state secret for 40 years.
Frequently Asked Questions
The epicenter is the point on the Earth's surface directly above the hypocenter (focus) where the earthquake rupture begins. It is typically reported as latitude and longitude coordinates. The strongest shaking usually occurs near the epicenter, though local soil conditions and fault geometry can shift the zone of maximum damage.
A seismograph (or seismometer) is an instrument that detects and records ground motion caused by seismic waves. Modern broadband seismometers can detect movements smaller than the width of an atom. Networks of seismographs around the world enable scientists to locate earthquakes and determine their magnitude within minutes.
P-waves (primary waves) are compressional waves that travel fastest through rock, arriving first at seismic stations. S-waves (secondary waves) are shear waves that arrive later but cause more ground shaking. P-waves travel through solids, liquids, and gases; S-waves only travel through solids. The time difference between them helps determine earthquake distance.
The hypocenter (or focus) is the point within the Earth where an earthquake rupture initiates. It is described by latitude, longitude, and depth. The vertical distance between the hypocenter and the surface directly above is the earthquake's depth, which strongly influences how the earthquake is felt at the surface.
Seismology is the scientific study of earthquakes and the propagation of seismic waves through the Earth. It encompasses earthquake detection, location, and characterization; Earth's internal structure; seismic hazard assessment; and earthquake engineering. Seismologists use data from global seismograph networks to study these phenomena.