Overcrowding and slums developed in many impoverished countries in the 20th century, mostly due to large migrations to cities from people looking for work.
The climate of the costal plain is mild. It has hot summers and cool winters and few hard freezes.
Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.
