Learning about Earthquakes and Volcanoes is made much easier once you understand Plate Tectonics. Earthquakes and Volcanoes are found mostly around active plate boundaries. (Hotspots can also create Volcanoes in areas without active plate boundaries) Below are some links and information that will assist you in understanding these two topics.
Magnitudes Effects
Less than 3.5 ---Generally not felt, but recorded.
3.5-5.4 --------- Often felt, but rarely causes damage.
Under 6.0 ------ At most slight damage to well-designed buildings.
Can cause major damage to poorly constructed buildings
over small regions.
6.1-6.9 ------ Can be destructive in areas up to about 100 kilometers
across where people live.
7.0-7.9 ----- Major earthquake. Can cause serious damage over larger areas.
8 or greater Great earthquake. Can cause serious damage in areas several hundred kilometers across.
