Seismic Network
Definition
A coordinated group of seismograph stations that continuously monitor earthquake activity. The Global Seismographic Network (GSN) includes 150+ stations providing worldwide coverage.
Example
Japan's Hi-net seismic network has over 800 stations, the densest in the world.
Related Terms
Related Guides
Understanding the Moment Magnitude Scale
The moment magnitude scale (Mw) is the modern gold standard for measuring earthquakes. Learn how it works and why it replaced the Richter scale.
P-Waves and S-Waves: How Seismic Waves Travel
Learn how P-waves and S-waves travel through Earth, why P-waves arrive first, and how scientists use them to locate earthquakes.
Epicenter vs Hypocenter: What's the Difference?
The epicenter is on the surface; the hypocenter is underground. Learn how scientists locate both and why the distinction matters for safety.
Aftershocks Explained: Why Earthquakes Come in Clusters
Aftershocks can continue for months or years after a major earthquake. Learn what causes them, how they're predicted, and when they'll stop.
Foreshocks: Can They Predict the Main Event?
Foreshocks occur before some major earthquakes, but can they be used for prediction? Learn the science behind foreshocks and their limitations.
Earthquake Swarms: When Small Quakes Won't Stop
Earthquake swarms produce hundreds of small tremors without a clear mainshock. Learn what causes them and whether they signal bigger events.
Earthquake Frequency: How Often Do They Happen?
About 500,000 earthquakes occur yearly, but only 100 cause damage. Learn the frequency-magnitude relationship and why big quakes are rare.
The 1976 Tangshan Earthquake: China's Deadliest Disaster
The 1976 M7.5 Tangshan earthquake killed an estimated 242,000 people. The deadliest earthquake of the 20th century.
The 1964 Alaska Earthquake: The Great Alaskan Quake
The 1964 M9.2 Alaska earthquake was the most powerful earthquake in US history. Its lessons shaped modern building codes and tsunami science.
The 2010 Chile Earthquake: Megathrust Lessons
The 2010 M8.8 Chile earthquake showed how strong building codes save lives. Lessons from one of the largest earthquakes ever recorded.
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.