It seems like there are more and more earthquakes worldwide. Is that also true?
The frequency of earthquakes is fairly constant, although the number varies every year. If you look at the number of shocks with a force of 7 to 8 on the Richter scale, there are an average of 17 a year. Sometimes there are only six, such as in 1986 and 1989, or more than 30, such as in 1943, but over a long period - for example 50 or 100 years - the number of earthquakes is constant.
If there seem to be more earthquakes at times, it is because only the very severe or destructive shocks make the news, such as earthquakes that lead to a tsunami. From a human point of view, the effect of an earthquake cannot be indicated by a number on some scale; then we should count on lives, material damage and economic losses.
Of the 17 annual earthquakes that have a force of 7 to 8 on the Richter scale, perhaps only one is so devastating that we hear about it. And we do remember the earthquake that struck Haiti on January 12, 2010 and possibly cost 300,000 people - but we have forgotten the earthquake that hit the Japanese Riukiu Islands six weeks later. And that while they both had a force of 7.0 on the Richter scale.
That the number of shocks is constant over a long period is logical when you think of the underlying processes. The crust of the earth moves as a result of an even force within the earth. In a zone where two plates collide, tension is gradually built up. This means that a similar amount of energy is always released in earthquakes.
Number of earthquakes is constant
The number of earthquakes is constant over a longer period of time. On average there are 17 annually with a power of 7 to 8. From the year 2000 the number is slightly lower