Earthquake in Russia and Tsunami: why are we always talking about the Richter scale … wrongly

During the night of July 29 to 30, 2025, an earthquake of an 8.8 magnitude was recorded off the Russian Kamchatka peninsula, causing a tsunami alert throughout the peaceful area. An exceptional value, but many have interpreted it as defined by the Richter scale. Yet outdated since 1960, this scale of magnitude is still deeply anchored in the media and culturally, despite its proven gaps.

Richter, the fallen star of earthquakes

The media are those that use the Richter scale the most, because it is easy to understand by the population. Created in 1935, it takes into account local magnitude (noted M_L), a relevant measure for instruments close to the earthquake, but which also tends to saturate during high magnitude events (generally beyond 6.5-7). It therefore cannot always reflect with precision the increase in energy released for very large earthquakes. Established by Charles Francis Richter, American seismologist and physicist, she responded to a discipline that appeared on the outskirts of the 20th century: the precise analysis and census of earthquakes.

Before its appearance, the only way to gauge a movement of the terrestrial bark was the scale of Mercalli, created in 1902 by the Italian seismologist and volcanologist Giuseppe Mercalli. This evaluated the earthquakes only on their intensity, depending on the damage caused on the surface. Too approximate, therefore.

Charles Francis Richter sought to establish a scientific means of evaluating Californian earthquakes. This is how he defined the concept of magnitude in seismology, a concept which corresponds to the energy mass released by the rupture of a seismic fault.

However, the magnitude of an earthquake must be differentiated from its intensity, too often confused. Indeed, the intensity concerns local damage, the feelings of the inhabitants, and it therefore varies according to the place and the composition of the soil. Magnitude does not evolve, because it is the energy released to the flaw by the shock.

Why the Richter scale is no longer the weight

From a scientific point of view, the Richter scale remains somewhat imprecise. It was defined on the Californian soil database, which complicates its application on a global scale. In addition, local magnitude does not allow the epicenter of the earthquake precisely, which distorts the identification and power of phenomena. It is therefore not representative enough for today’s scientists.

In other words, even if it has long been considered a high quality measure, modern alternatives appeared in the second half of the 20th century, escaping these reproaches. In the late 1970s, local magnitude thus gave way to “magnitude of moment” (noted M_W), both more precise and more reliable.

The magnitude of moment, a real current star

Like the Richter scale, the magnitude of moment is logarithmic, that is to say that an increase in one unit corresponds to an energy approximately 32 times more important than the previous one. In other words, an earthquake of magnitude 6 frees approximately 32 times more energy than an earthquake of magnitude 5.

And unlike the latter, which is based on the amplitude of locally measured waves, the magnitude of the moment is based on physical data (the surface of the broken fault, the displacement and the rigidity of the rocks), which makes it more reliable and universal, especially for earthquakes of high intensity or very deep.

Note that the magnitude of moment is dependent on the instruments or the location, which contributes greatly to its adoption by the community of seismologists to the detriment of the Richter scale.

In short, forget Richter!

In the scientific community, the latter has become cheesy, outdated. However, the media and the general public continue to use it, wrongly since these are values expressed in magnitude of moment.