They connect points of equal elevation. A steep-sided mound that forms when very viscous lava is extruded from a volcanic vent. A volcano that is not expected to erupt again. Continuous rhythmic earthquakes in the Earth's upper lithosphere that can be detected by seismographs. Harmonic tremors often precede or accompany volcanic eruptions.
Volcanoes sometimes occur above a hot spot.
The water that covers 71 percent of the Earth's surface as oceans, lakes, rivers, and streams. The hydrosphere also includes ground water, water that circulates below the Earth's surface in the upper part of the lithosphere. A sideways-directed explosion from the side or summit of a volcano. The term used for magma once it has erupted onto the Earth's surface. The Earth's hard, outermost shell.