# Is a 6 4 earthquake devastating

## Earthquake strength

In contrast to the Richter magnitude, the sky wave magnitude (mb) uses seismic waves that run through the deep interior of the earth and are recorded at stations that are more than 2000 km away. This magnitude is still determined very quickly. For strong earthquakes (> mb 6), however, the sky wave magnitude is considered to be saturated, so that the magnitude hardly increases any more, although the earthquake was much stronger. Surface waves travel relatively slowly along the earth's surface (speeds of around 3-4 km / s compared to 6-14 km / s for the P waves and 4-7 km / s for S waves in the interior of the earth), but they can travel long distances can still be measured well at the source of the earthquake. The surface wave magnitude (MS) determined from these waves only saturates during stronger earthquakes and has long been used to characterize strong earthquakes. However, the slow speed of propagation means that MS is only present some time after the earthquake.

Nowadays earthquakes and stronger earthquakes are mainly characterized by the moment magnitude (Mw), which is no longer saturated and can be directly linked to the physical parameters at the source of the earthquake. To determine this magnitude, theoretical seismograms are usually calculated for the earth and compared with observations. In the case of strong earthquakes, surface waves are essentially compared, which is why Mw cannot be present immediately after the earthquake has occurred.

In media coverage of earthquakes, the "Richter scale open to the top" is often used. This suggests that earthquakes with a magnitude of 100 or 1,000 are also possible. Such earthquakes have never been measured so far, and the assumption that such an earthquake could occur also makes little physical sense. Charles Richter originally set his intensity scale at 12, but did not see this value as a fixed limit. How should one imagine an earthquake that is at the upper end of the Richter scale? A realistic example of this is provided by the great earthquake in Chile on May 22, 1960. This is still the earthquake with the largest magnitude that has ever been measured. At that time, the earth's crust, 40 kilometers thick, tore open in its entirety over a length of 1,000 kilometers and was shifted by around 10 meters. The quake destroyed almost 60,000 buildings and reached a magnitude of 9.5 to 10.Although it was a very severe earthquake in which an entire continent was torn open, it did not reach the upper value of 12 on the Richter scale What should an earthquake event look like that would be displayed on the Richter scale with a value of 50, 100 or 1,000? Such an event would be difficult to imagine.