KnowraSeismologySeismologyThe study of seismic waves and earthquakes, used to locate earthquakes and to image Earth's interior structure.BriefConnectP-wave: The fastest seismic wave, a compressional wave that travels through solids, liquids and gases. First arrival at a seismometer; its travel time fixes the earthquake's distance.1755 Lisbon earthquake: A magnitude ~8.5 earthquake and tsunami that destroyed Lisbon on All Saints' Day, 1755. Its systematic study across Europe is often called the birth of modern seismology.Richard Dixon Oldham: British geologist who in 1906 identified distinct P, S and surface arrivals and evidence for a core. His travel-time curves first separated Earth's layered interior.Fault (geology): A fracture in rock along which blocks on either side have moved relative to each other. Nearly all damaging earthquakes are slip on a fault.Seismic tomography: Imaging Earth's interior in three dimensions from variations in seismic wave speeds. Maps mantle convection and slab sinks that drive the plates.S-wave: A shear seismic wave that travels only through solids, arriving after the P-wave. Its inability to cross liquids proved Earth's outer core is molten.Robert Mallet: Irish engineer who coined the word seismology and mapped seismic waves experimentally in the 1850s. First treated earthquakes as measurable waves rather than divine events.Beno Gutenberg: Seismologist who in 1914 fixed the core–mantle boundary at about 2,900 km depth. Located the discontinuity that produces the shadow zones.Hypocenter: The point within Earth where an earthquake rupture begins; its surface projection is the epicenter. Seismologists locate it from P- and S-arrival time differences.Comprehensive Nuclear-Test-Ban Treaty: A 1996 treaty banning nuclear explosions, verified by a global seismic monitoring network. Distinguishing explosions from earthquakes is seismology's largest applied program.Show all 27Linked from 47 pagesHistory of geophysicsBroader topic: Earthquake waves revealed deep structure that direct observation could not reach.Plate tectonicsRelated: Global earthquake distribution mapped the plate boundaries before plates were named.Seismic waveNarrower topic: Seismology uses wave observations to infer earthquakes and Earth's internal structure.AcousticsRelated: Seismic waves share mechanical-wave principles with sound but travel through geological structures.Earthquake engineeringNarrower topic: Earthquake engineering draws on seismology to characterize sources and shaking.San Andreas FaultRelated: The 1906 rupture created the field's founding dataset and its first fault-rupture measurements.SeismometerNarrower topic: Seismometers provide the observations on which much of the field relies.Volcano monitoringRelated: Earthquake patterns can reveal magma movement and changes in volcanic conduits.Show all 47