There are probably several million earthquakes in the world every year, but the majority of these are too weak to be detected with current instruments. Some earthquakes which are large enough to be detected may also go unnoticed because they occur in isolated areas where there are no seismographs to pick up the tremors.
For example, while it is estimated by the US Geological Survey that there are 1.3 million earthquakes worldwide each year registering between 2 and 2.9 on the Richter Scale, only 3643 of these were detected in 2011. In total the National Earthquake Information Center reports about 20,000 earthquakes per year.
More about earthquakes:
- The most powerful earthquake on record occurred in Chile in 1960, and measured 9.5 on the Richter Scale.
- Roughly 80% of the world's earthquakes occur around the Ring of Fire, a massive area in the Pacific where several tectonic plates intersect.
- Most of the damage and fatalities associated with earthquakes happen as a result of secondary disasters triggered by the quake, such as tsunamis or fires.