keisoku

Earthquake Energy Calculator

Calculate the energy (J) an earthquake releases from its magnitude. Convert it to TNT and Hiroshima bombs to grasp the true scale.

Input

Enter a magnitude to estimate the energy an earthquake releases using the Gutenberg-Richter relation log₁₀E = 4.8 + 1.5M (E in joules). Each whole step up in magnitude releases about 32 times more energy.

M

Result

Earthquake energy (estimate)

2.0 × 10^15J

Magnitude

M 7.0

Equivalent TNT

about 476.9 kilotons

Hiroshima bombs

about 32 bombs

Estimated using 1 ton of TNT = 4.184×10⁹ J and one Hiroshima-type bomb ≈ 6.3×10¹³ J. Actual damage depends heavily on focal depth, ground conditions, and distance from the epicenter.

Energy comparison by magnitude

MagnitudeEnergy (J)TNT equivalentTypical scale
M 3.02.0 × 10^9about 476.9 kgMinor quake (sometimes felt)
M 5.02.0 × 10^12about 477 tonsModerate quake (damage may begin)
M 6.06.3 × 10^13about 15.1 kilotonsFairly strong quake
M 7.02.0 × 10^15about 476.9 kilotonsMajor quake (e.g. Great Hanshin earthquake, M7.3)
M 8.06.3 × 10^16about 15.1 megatonsGreat quake
M 9.02.0 × 10^18about 476.9 megatonsMegathrust quake (e.g. 2011 Tohoku earthquake, M9.0)

How it works

  • Uses the relation log10E = 4.8 + 1.5M (E in joules) to derive an earthquake's energy E from its magnitude M. This is the empirical formula established by Gutenberg and Richter.
  • Under this formula, each one-step increase in magnitude multiplies the energy by about 32 (10 to the 1.5 power), and a two-step increase multiplies it by about 1000.
  • The TNT conversion assumes 1 ton of TNT = 4.184×10^9 joules.
  • The Hiroshima-bomb conversion treats that bomb's energy as about 6.3×10^13 joules (roughly 15 kilotons of TNT).
  • The values shown are theoretical estimates derived from magnitude alone. Actual shaking and damage vary greatly with focal depth, distance from the source, and ground conditions.
  • For decisions about earthquake scale or disaster preparedness, always check the latest information from official agencies such as the Japan Meteorological Agency. Use this tool's results as a rough guide only.