to answer back; to talk again (trả lời)

waves of energy that travel through the Earth

To cause to burst in pieces by force from within. To blow up

Large pieces of earths crust that move due to convection currents.

southern lights; caused by solar wind

to hit something

A volcano that has not erupted for a long time, but may erupt again one day.

a colorful, glowing display in the sky caused when particles from the sun strike oxygen and nitrogen atoms in the ionosphere; also called the Northern Lights

a serious or dangerous situation that needs immediate action

A theory stating that the earth's surface is broken into plates that move.

training exercises (cuộc tập trận)

a flow of hot liquid rising into the air when a volcano erupts

inspiring awe or admiration or wonder steam