Earthquake Energy Calculator
Earthquakes release seismic energy in the form of seismic waves that travel through the Earth. The USGS uses the empirical formula log(E) = 1.5M + 4.8 to estimate the total radiated seismic energy E (in joules) from the moment magnitude M. Each full integer increase in magnitude corresponds to about 31.6 times more energy release (10 raised to the power 1.5). The formula was developed from observations of radiated seismic energy and is published in USGS Fact Sheet 017-03. Enter any moment magnitude to calculate seismic energy in joules, terajoules, and TNT equivalent.
Earthquake energy formula (USGS)
log10(E) = 1.5 * M + 4.8
E (joules) = 10^(1.5 * M + 4.8)
E (terajoules) = E / 10^12
TNT equivalent (kilotons) = E / 4.184e12
The formula log10(E) = 1.5M + 4.8 is from USGS Fact Sheet 017-03 (Richter 1958, updated). The conversion to TNT equivalent uses 1 kiloton TNT = 4.184 * 10^12 joules (1 ton TNT = 4.184 * 10^9 joules, per NIST standards).
Earthquake magnitude energy scale
- M2.0: about 63,000 joules (felt slightly by people nearby)
- M4.0: about 2 * 10^9 joules (63 MJ, shaking felt widely)
- M5.0: about 2 * 10^10 joules (moderate earthquake, some damage)
- M6.0: about 6.3 * 10^13 joules (strong earthquake, significant damage)
- M7.0: about 2 * 10^15 joules (major earthquake, serious damage over large area)
- M8.0: about 6.3 * 10^16 joules (great earthquake, devastating, felt thousands of miles away)
- M9.0: about 2 * 10^18 joules (rare mega-earthquake, widespread destruction)
Frequently asked questions
How is earthquake energy calculated from magnitude?
The USGS uses the empirical relationship log10(E) = 1.5 * M + 4.8, where E is seismic energy in joules and M is moment magnitude (Mw). This formula means each integer increase in magnitude releases about 31.6 times more energy (10^1.5 = 31.6).
What is moment magnitude (Mw)?
Moment magnitude (Mw) is the modern standard for measuring earthquake size, based on the seismic moment (product of fault area, slip distance, and rock rigidity). It is accurate across all earthquake sizes, unlike the older Richter local magnitude scale which saturates above M7.
How does earthquake energy compare to nuclear weapons?
The 1 megaton nuclear bomb releases about 4.18 * 10^15 joules of energy. A magnitude 6.0 earthquake releases roughly 6.3 * 10^13 joules (about 1/70th of a megaton). A magnitude 9.0 earthquake releases about 2 * 10^18 joules, equivalent to about 480 megatons.
Why does the Richter scale seem to underreport large earthquakes?
The original Richter scale (local magnitude, ML) was calibrated for Southern California earthquakes on short-period seismometers. It saturates above M7 because the seismic waves that seismometers measure reach their maximum at those frequencies. Moment magnitude Mw does not saturate.
What is the largest earthquake ever recorded?
The 1960 Valdivia earthquake in Chile is the largest ever recorded at M9.5 moment magnitude. It released an estimated 2.5 * 10^19 joules of seismic energy. The 2011 Tohoku earthquake in Japan was M9.1, releasing about 3.6 * 10^18 joules.
Official sources
- USGS: USGS Earthquake Hazards Program.
- USGS: Earthquake Energy and Magnitude.
- USGS: Fact Sheet 017-03: Earthquake Magnitude, Energy, and Intensity.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.