Earthquakes mainly occur around the Pacific Ocean and the coastlines bordering on it. These are the coastlines of: eastern region of Asia and Oceania, and the western region of North and South America. A pattern of earthquakes continue around the coastlines of the following regions: Chile, Peru, west Mexico, west of U. S. A. , South of Alaska, Aleutian Islands, Japan, Philippines, Vanuatu, and Fiji islands.
Some earthquakes occur off coast. However, based on the map on Q 1, these earthquakes generally occur within approximately 150 km to 1000 km range, from the above regions. Active volcanoes are not scattered over the Earth randomly. Instead they tend to bunch up close with each other in particular regions - especially the regions that are bordering the Pacific Ocean. Active volcanoes occur on the coastlines or in-land of: eastern region of Asia and Oceania, Western and central region of Africa, and the western region of North and South America.
Volcanic eruptions tend to occur frequently on the following regions: west Mexico, western region of U. S. A. , Aleutian Islands, far eastern region of Russia, Japan, Philippines, Vanuatu, Indonesia, New Guinea, the Mariana Islands, northern New Zealand, Kenya and Uganda. Although most volcanic eruptions occur on coastlines, based on the map in Q 1, they can occur inland by up to 500 km away from the nearest coast. In terms of where they are located, volcanic eruptions seem to occur, more bunched up in specific places, whereas the earthquakes seem to be more spread out.
An example would be volcanic eruptions in the eastern Russia and Mexico. Volcanoes in these regions are located closely together - less than 200 km apart. In contrast, the earthquakes in the western border of South America are more spread out, although they do leave a clear trail that continues from the North West end to the South West end. Volcanic eruptions generally occur at a distance of some hundreds of kilometers from the majority of earthquakes. However there is a relationship between the two. The surface of the Earth (the crust) is broken into units called plates.
These plates float over the hot asthenosphere, and move around 1 to 10 cm a year. At the boundaries where the plates meet is where most volcanic eruptions and earthquakes both occur. An example would be a clear pattern of earthquakes and volcanoes called the Pacific ring of fire, occurring on the edge of the Pacific plate.