It is not true that most earthquakes occur on the west coast. In fact, most earthquakes occur along plate boundaries, which are found in many parts of the world. Some of the regions with the highest seismic activity include:

1. Circum-Pacific Belt (Ring of Fire): This horseshoe-shaped region surrounding the Pacific Ocean experiences around 90% of the world's earthquakes and 81% of the strongest earthquakes. It includes the west coast of the Americas, Japan, the Philippines, Indonesia, New Zealand, and Alaska.

2. Mediterranean Sea: This region is also prone to significant seismic activity due to the complex interactions between the African, Eurasian, and Arabian tectonic plates.

3. Alpine-Himalayan Belt: This zone stretches from Europe through Turkey, Iran, Afghanistan, and the Himalayas. It hosts some of the most seismically active areas globally, including Italy, Greece, and India.

4. Mid-Atlantic Ridge: Although less prevalent than in other regions, earthquakes can occur along the Mid-Atlantic Ridge, where new oceanic crust is constantly forming.

Earthquakes occur when these tectonic plates shift, slip, or collide with each other. The west coast of the Americas is indeed located along the Circum-Pacific Belt and experiences significant seismic activity. However, other regions mentioned above also have notable earthquake occurrences.