Geophysics
17 questions tagged Geophysics — spanning every one of the seven Ws.
Why Does the Earth Have a Magnetic Field?
Earth magnetic field is generated by the geodynamo — convection currents of molten iron and nickel in the outer core, driven by heat escaping from the inner core.
What is isostasy?
Isostasy is the balance of Earth's crust floating on the mantle beneath it. Heavier or thicker crust sinks deeper, while lighter crust rides higher.
When was the mid-ocean ridge magnetic striping pattern discovered?
In the early 1960s, especially after 1963, when scientists identified symmetrical magnetic anomalies on either side of ridges.
When was the Earth’s inner core first identified as solid?
In 1936, when Inge Lehmann concluded that Earth has a solid inner core inside a liquid outer core.
When was Earth’s liquid outer core first inferred?
In 1906, when Richard Oldham used earthquake waves to show that a fluid layer surrounds the core.
When was the first underwater earthquake observatory installed?
Early underwater earthquake observatories began appearing in the late 20th century, with major seafloor monitoring systems installed in the 1990s and 2000s. They improved tsunami and tectonic research.
Which continent has the thickest average continental crust?
Asia, especially the Tibetan Plateau and Himalaya region, is associated with the thickest continental crust on Earth, reaching around 70 kilometers or more in places.
Whose work revealed magnetic stripes on the ocean floor?
Fred Vine and Drummond Matthews explained the magnetic striping of the seafloor in 1963. Their idea showed that Earth's magnetic field has reversed many times.
Whose discovery of seismic waves transformed the study of earthquakes?
Beno Gutenberg is credited with major advances in seismology, including identifying Earth's core boundary in 1914. His work helped make earthquake waves a tool for studying Earth's interior.
Whose discovery explained the cause of tsunami generation by seafloor movement?
Harold Jeffreys and later geophysicists helped formalize the idea that sudden seafloor displacement creates tsunamis. Their work built the science behind modern tsunami warnings.
Where is the strongest naturally occurring magnetic field at Earth’s surface measured?
Extremely strong natural magnetic fields can be measured near magnetite-rich rocks, including some iron ore deposits and volcanically altered rocks. But Earth’s strongest sustained surface fields are local geological anomalies, not one single famous place.
Whose idea linked seafloor spreading to magnetic stripes on the ocean floor?
Frederick Vine, Drummond Matthews, and Lawrence Morley are credited with that breakthrough. Their 1963 work helped prove plate tectonics.
Why do earthquakes send different kinds of waves through Earth?
Earthquakes release energy in waves that move through rock in different ways, including compressional and shear waves. Those differences arise because Earth’s materials respond differently to pressure and sideways motion.
Whose theory linked Earthquakes and plate boundaries so clearly?
John Tuzo Wilson was a major figure in plate tectonics, especially for explaining transform faults and the idea of a hot spot track. His ideas helped make earthquake patterns understandable.
Whose discovery linked fossils to plate tectonics through magnetic stripes?
Frederick Vine and Drummond Matthews explained the magnetic stripes on the seafloor in 1963. Their work was crucial evidence for seafloor spreading.
Whose name is associated with the theory of isostasy?
George B. Airy and John Henry Pratt are both tied to early isostasy models. Their ideas explained how mountains can float in balance on denser Earth material below.
How do scientists measure the thickness of Earth's crust?
They use seismic waves, gravity data, and receiver functions to estimate where the crust ends and the mantle begins. The crust is about 5–10 km thick under oceans and roughly 30–70 km under continents.