Seismologist in the context of "Seismograph"

Herbert Hall Turner FRS (13 August 1861 – 20 August 1930) was a British astronomer and seismologist.

Seismic moment is a quantity used by seismologists to measure the size of an earthquake. The scalar seismic moment ${\displaystyle M_{0}}$ is defined by the equation${\displaystyle M_{0}=\mu AD}$, where

• ${\displaystyle \mu }$ is the shear modulus of the rocks involved in the earthquake (in pascals (Pa), i.e. newtons per square meter)
• ${\displaystyle A}$ is the area of the rupture along the geologic fault where the earthquake occurred (in square meters), and
• ${\displaystyle D}$ is the average slip (displacement offset between the two sides of the fault) on ${\displaystyle A}$ (in meters).

${\displaystyle M_{0}}$ thus has dimensions of torque, measured in newton meters. The connection between seismic moment and a torque is natural in the body-force equivalent representation of seismic sources as a double-couple (a pair of force couples with opposite torques): the seismic moment is the torque of each of the two couples. Despite having the same dimensions as energy, seismic moment is not a measure of energy. The relations between seismic moment, potential energy drop and radiated energy are indirect and approximative.

Thomas C. Hanks is an American seismologist. He works for the US Geological Survey (USGS) in Menlo Park, California. Dr. Hanks is a member of the Seismological Society of America, the American Geophysical Union, the Earthquake Engineering Research Institute, the Geological Society of America, the Peninsula Geological Society at Stanford, and many related geological societies. Dr. Hanks has authored dozens of scholarly papers in strong-motion seismology and tectonic geomorphology.

In 1979 the Japanese-American seismologist Hiroo Kanamori, professor of seismology at the California Institute of Technology and Dr. Hanks suggested the use of moment magnitude scale to replace the Richter magnitude scale for measuring the relative strength of earthquakes. The reason was that the Richter scale saturates at magnitudes greater than about 5.5, while the Moment magnitude scale does not saturate.

Hiroo Kanamori (金森 博雄, Kanamori Hiroo; born October 17, 1936) is a Japanese seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them.

A Wadati–Benioff zone (also Benioff–Wadati zone or Benioff zone or Benioff seismic zone) is a planar zone of seismicity corresponding with the down-going slab in a subduction zone. Differential motion along the zone produces numerous earthquakes, the foci of which may be as deep as about 670 km (420 mi). The term was named for the two seismologists, Hugo Benioff of the California Institute of Technology and Kiyoo Wadati of the Japan Meteorological Agency, who independently discovered the zones.

Wadati–Benioff zone earthquakes develop beneath volcanic island arcs and continental margins above active subduction zones. They can be produced by slip along the subduction thrust fault or slip on faults within the downgoing plate, as a result of bending and extension as the plate is pulled into the mantle. The deep-focus earthquakes along the zone allow seismologists to map the three-dimensional surface of a subducting slab of oceanic crust and mantle.

Beno Gutenberg (/ˈɡuːtənbɜːrɡ/; June 4, 1889 – January 25, 1960) was a German-American seismologist who made several important contributions to the science. He was a colleague and mentor of Charles Francis Richter at the California Institute of Technology and Richter's collaborator in developing the Richter scale for measuring an earthquake's magnitude.

The 1755 Lisbon earthquake, also known as the Great Lisbon earthquake, hit Portugal, the Iberian Peninsula, and Northwest Africa on the morning of Saturday, 1 November, Feast of All Saints, at around 09:40 local time. In combination with subsequent fires and a tsunami, the earthquake almost completely destroyed Lisbon and adjoining areas. Seismologists estimate the Lisbon earthquake had a magnitude of 7.7 or greater on the moment magnitude scale, with its epicenter in the Atlantic Ocean about 200 km (110 nmi; 120 mi) west-southwest of Cape St. Vincent, a cape in the Algarve region, and about 290 km (160 nmi; 180 mi) southwest of Lisbon.

Chronologically, it was the third known large-scale earthquake to hit the city (following those of 1356 and 1531). Estimates place the death toll in Lisbon around 30,000–40,000. A further 10,000 may have died in Morocco.