The up’s and down’s of earthquakes
Earthquakes between 5.5 and 6.1 in magnitude result in moderate damage to buildings. Only around 500 of these occur each year.
Earthquakes measuring less than 3.4 can only be detected by seismometers.
With this in mind, around 800 000 earthquakes measuring 3.4 or less are recorded each year.
Earthquakes measuring between 3.5 and 4.2 can be felt indoors and around 30 000 of these occur each year.
Earthquakes with a magnitude of between 4.3 and 4.8 will be noticed by just about everyone and occur around 4 800 times each year.
Magnitude 4.9 to 5.4 earthquakes have more noticeable effects but only 1 400 occur each year.
Earthquakes between 5.5 and 6.1 in magnitude result in moderate damage to buildings. Only around 500 of these occur each year.
Earthquakes measuring between 6.2 and 6.9 result in much more damage and can cause house foundations to move. About 100 of these are experienced around the world each year.
At between 7.0 and 7.3, earthquakes are extremely damaging and can cause bridges to twist, walls to crack and buildings to collapse. Only about 15 of these take place worldwide each year.
Earthquakes measuring between 7.4 and 7.9 will cause most buildings to collapse. There are around four which hit worldwide each year.
All earthquakes measuring over eight occur only once every five to 10 years and the results are devastating. Surface waves can be seen and objects will be thrown into the air. This magnitude quake will most likely result in total damage.
r Information obtained from www.matter.org.uk
