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Earthquake Magnitude and Energy Calculator

Earthquake magnitude describes source size, while intensity describes shaking and effects at a particular place. GeoMiner compares two entered values as moment magnitude, Mw, and calculates both scalar seismic moment and a rough radiated-energy estimate. The USGS metric-unit relationship is log base 10 of seismic moment in newton metres equals 1.5Mw plus 9.1. The rough Mw-to-energy conversion is log base 10 of energy in joules equals 5.24 plus 1.44Mw. The ratio from that fitted energy relationship is about 27.5 for one magnitude step. The familiar general rule of thumb is approximately 31.6 times the radiated energy and ten times the measured amplitude per whole magnitude step; GeoMiner labels those relationships separately instead of silently treating them as one formula. Joules convert to kilowatt-hours using 3.6 million joules per kilowatt-hour and to tons of TNT as an energy unit using 4.184 billion joules per ton. Those conversions do not describe electricity generated, explosive action, local shaking, or damage. Local magnitude, body-wave magnitude, surface-wave magnitude, duration magnitude, moment magnitude, energy magnitude, and other magnitude families use different measurements, distance ranges, frequency bands, and useful ranges. A reported value should be compared with its magnitude type, issuing agency, revision, origin time, location, depth, and uncertainty. Values that are not Mw, or that lie outside a method's useful range, make the displayed absolute estimates mathematical illustrations rather than measurements. Intensity and damage vary with source distance, focal depth, rupture geometry and direction, frequency content, duration, local bedrock, sediment, groundwater, topography, structures, and preparedness. Magnitude alone cannot predict tsunami generation, landslides, liquefaction, fire, aftershocks, evacuation needs, safe re-entry, structural performance, insurance impact, or personal risk. For an actual event, use the issuing geological agency and local emergency authorities. Inputs remain in the browser. Analytics retain only bounded action, broad first-magnitude band, and magnitude-difference band categories—never exact magnitudes, event names, dates, coordinates, depth, place, agency, damage, notes, or search text.

Verification resources

Cross-check terminology, classification, methods, and safety with these authoritative external resources.

  • undefined. The logarithmic comparison, the rough moment-magnitude-to-energy equation used for absolute estimates, and why intensity and damage depend on additional factors.
  • undefined. Published magnitude families, useful ranges, and the metric-unit moment-magnitude equation used for the seismic-moment estimates.
  • undefined. Why local, body-wave, surface-wave, and moment magnitudes are different measurements with different applicable frequency and distance ranges.
  • undefined. Canadian guidance separating source magnitude from site-specific intensity and describing the roughly 30-fold energy increase per magnitude step.
  • undefined. Joule conversions for watt-hours and the energy equivalent of one ton of TNT.

Read GeoMiner's editorial methodology.

Common questions

How much more energy does one magnitude step represent?
The familiar rule of thumb is about 31.6 times the radiated energy for one magnitude step and about 1,000 times for two. The USGS rough Mw-to-energy equation used for the absolute estimates gives about 27.5 times per step, so the tool shows those relationships separately.
Is earthquake magnitude the same as intensity?
No. Magnitude characterizes the earthquake source. Intensity describes shaking and effects at a particular place and varies with distance, depth, rupture, geology, soils, structures, and other conditions.
Is every reported magnitude a Richter magnitude?
No. Local, body-wave, surface-wave, duration, moment, energy, and other magnitude types use different observations and useful ranges. Moment magnitude is preferred for large earthquakes.
Does this calculator predict damage or tsunami risk?
No. Magnitude alone cannot predict local shaking, damage, landslides, liquefaction, fire, tsunami, aftershocks, or personal risk. Use official geological and emergency-management information for an actual event.
Why is the energy result approximate?
The tool uses the USGS rough conversion log E = 5.24 + 1.44Mw. Actual radiated energy comes from broadband seismic records, while energy magnitude and moment magnitude describe different properties.
Can earthquake magnitudes be negative or exceed 9?
Small instrument-recorded events can have negative magnitudes. Earth has produced earthquakes above magnitude 9, but this educational calculator limits entries to −2 through 10 and treats every value as Mw for the displayed mathematical estimates.

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