Enter two earthquake magnitudes to compare their relative shaking amplitude and energy release. The Richter Scale Calculator takes Magnitude 1 and Magnitude 2 and tells you how many times stronger one earthquake is than the other — both in ground motion and in the seismic energy unleashed.
Times Stronger (Shaking Amplitude)
--
Times More Energy Released
--
Magnitude Difference
--
Energy of Magnitude 1 (Tons of TNT)
--
Energy of Magnitude 2 (Tons of TNT)
--
The Richter scale, developed by Charles Richter in 1935, measures the magnitude of an earthquake based on the amplitude of seismic waves recorded by a seismograph 100 km from the epicenter. It is a logarithmic scale, meaning each whole-number increase represents a 10-fold increase in shaking amplitude and roughly 31.6 times more energy released.
A magnitude 8 earthquake is 100 times greater in shaking amplitude than a magnitude 6 (10 × 10, because the difference is 2 steps). In terms of energy released, it is approximately 1,000 times more powerful (31.6 × 31.6 ≈ 1,000).
The Richter scale (ML) was designed for local California earthquakes and becomes less accurate for very large or distant events. The moment magnitude scale (Mw) replaced it as the modern standard because it works consistently across all sizes and distances, measuring the total energy released using the seismic moment. For most practical comparisons, the two scales give similar values up to about magnitude 7.
The amplitude ratio between two earthquakes is calculated as 10^(M1 − M2), where M1 and M2 are their respective magnitudes. The energy ratio is calculated as 10^(1.5 × (M1 − M2)), since energy scales as the 1.5 power of the amplitude ratio on a logarithmic scale.
The Modified Mercalli Intensity (MMI) scale measures the observed effects of an earthquake — how strongly shaking is felt by people and how much damage occurs — on a scale from I (not felt) to XII (total destruction). Unlike the Richter or moment magnitude scales, it is not a single number for an earthquake but varies by location relative to the epicenter.
The most powerful earthquake on record is the 1960 Valdivia earthquake in Chile, with a magnitude of 9.5. Other notable events include the 1964 Alaska earthquake (9.2), the 2004 Indian Ocean earthquake (9.1–9.3), and the 2011 Tōhoku earthquake in Japan (9.1). These mega-quakes release energy equivalent to millions of atomic bombs.
Drop to your hands and knees, take cover under a sturdy table or desk, and hold on until the shaking stops. Stay away from windows, exterior walls, and heavy objects that could fall. If outdoors, move away from buildings, streetlights, and utility wires. Do not run outside during shaking, and never use elevators after an earthquake.
Yes. The Richter and moment magnitude scales have no fixed lower bound. Very small seismic events — such as those caused by mining blasts or minor tremors — can have negative magnitudes (e.g. −1 or −2). These events are far too small to be felt by humans and are detected only by sensitive instruments.