---
title: "Earthquake magnitude vs. intensity"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source: https://www.usgs.gov/programs/earthquake-hazards/earthquake-magnitude-energy-release-and-shaking-intensity
source_license: "public domain (US government work)"
attribution: "Summary by iinventedlight (AI-assisted). Source: U.S. Geological Survey (USGS), \"Earthquake Magnitude, Energy Release, and Shaking Intensity\" (public domain (US government work))."
condensed_by: "iinventedlight (Grok Bot, AI-assisted)"
fact_checked: 2026-10-14
date: 2026-10-14
status: reviewed
reviewed_on: 2026-10-14
category: science
checked_on: 2026-10-14
sources:
  - id: S1
    title: "Earthquake Magnitude, Energy Release, and Shaking Intensity"
    publisher: U.S. Geological Survey (USGS)
    url: https://www.usgs.gov/programs/earthquake-hazards/earthquake-magnitude-energy-release-and-shaking-intensity
    accessed: 2026-10-14
    license: "public domain (US government work)"
---
# Earthquake magnitude vs. intensity

## Summary
Magnitude is one number for an earthquake's size; each whole-number step means 10x the measured wave amplitude and about 32x the energy. Intensity (Modified Mercalli, Roman numerals) is the shaking at a given place and varies by distance, depth, and local ground. Moment magnitude (Mw) has largely replaced the Richter scale.

> **General science information for reference; for safety decisions during storms or earthquakes, follow NOAA/NWS and local emergency officials.**

## Facts
- id: F1
  claim: An earthquake has a single magnitude, but shaking intensity varies from place to place.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F2
  claim: Each whole-number increase in magnitude is a tenfold increase in measured amplitude on a seismogram.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F3
  claim: Each whole-number increase in magnitude releases about 32 times more energy.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F4
  claim: The Richter scale (ML), introduced by Charles Richter in 1935, is now mostly used only for small local earthquakes; moment magnitude (Mw) is more accurate for others.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F5
  claim: Moment magnitude is based on seismic moment, which is rock rigidity times fault area times slip.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F6
  claim: The U.S. uses the Modified Mercalli Intensity scale, written in Roman numerals.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F7
  claim: Shallower earthquakes and soft ground generally produce stronger shaking than deep ones or bedrock.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
- id: F8
  claim: USGS considers a magnitude 10.5 earthquake highly unlikely because Earth lacks a long enough fault system.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0

## Pointers
- answers: Magnitude types table
  where: https://www.usgs.gov/programs/earthquake-hazards/earthquake-magnitude-energy-release-and-shaking-intensity
  access: open