moment magnitude scale

Thân thiện

A scientist points to a chart of the moment magnitude scale during a lecture.

Definition

1. Noun:
   • A logarithmic scale for measuring the size of earthquakes: The moment magnitude scale is a modern, quantitative measure of an earthquake's size. It is based on the seismic moment, which is a product of the area of the fault that ruptured, the average amount of slip on the fault, and the rigidity of the rocks involved. It supersedes older scales like the Richter scale for most scientific purposes because it provides a more accurate and consistent measure, especially for very large earthquakes. The scale is logarithmic, meaning each whole number increase represents a roughly 32-fold increase in energy released.

Usage Examples

• Noun:
  • The 2011 Tōhoku earthquake was assigned a magnitude of 9.1 on the moment magnitude scale.
  • Seismologists now prefer the moment magnitude scale over the Richter scale for reporting large earthquakes.
  • The earthquake's magnitude was recalculated using the moment magnitude scale, providing a more precise estimate of its total energy.

Advanced Usage

• "Moment magnitude" (often abbreviated as M or Mw): This is the specific numerical value derived from the scale.
  • The quake had a moment magnitude of 7.8.
• "On the moment magnitude scale": The standard phrase for stating the measured value.
  • The event registered 6.4 on the moment magnitude scale.

Variants and Related Words

• Seismic moment (noun): The fundamental physical measurement (in units of force × distance, like newton-meters) upon which the moment magnitude scale is calculated. It quantifies the total energy released at the earthquake's source.
• Richter scale (noun): An older, more limited logarithmic scale for measuring earthquake magnitude, largely superseded by the moment magnitude scale for scientific work.
• Magnitude (noun): A general term for a number representing the size or brightness of an object or event (e.g., earthquake magnitude, stellar magnitude).

Synonyms

• Mw scale (Abbreviation, used primarily in scientific contexts).
• Energy magnitude scale (Descriptive synonym, though less common).

Related Phrases

• To measure on the moment magnitude scale: The action of determining the magnitude.
  • All major earthquakes are now measured on the moment magnitude scale.
• A reading on the moment magnitude scale: Refers to the obtained magnitude value.
  • The initial reading on the moment magnitude scale was later revised.

Học thuật

Noun

1. a logarithmic scale of 1 to 10 (a successor to the Richter scale) that enables seismologists to compare the energy released by different earthquakes on the basis of the area of the geological fault that ruptured in the quake