a  The area encircling the Pacific Ocean is called the "Ring of Fire," because its edges mark a circle of high volcanic and seismic activity (earthquakes). Most of the active volcanoes on Earth are located on this circumference.

b Tida l waves are the result of an abrupt shift in the underwater movement of the Earth". ... My book explains that "Tidal waves are the result of an abrupt shift in the underwater movement of the Earth".

c

d  Volcanologists can predict eruptions—if they have a thorough understanding of a volcano's eruptive history, if they can install the proper instrumentation on a volcano well in advance of an eruption, and if they can continuously monitor and adequately interpret data coming from that equipment.