Changes in topography, water chemistry, and gas output all are used to help predict:

A) volcanic eruptinons
B) mudflows
C) landslides
D) harmonic tremors

Volcanic Eruptions

The violent expulsion of magma, ash, and gases from a volcano, often associated with lava flow and pyroclastic debris.

Topography

The general configuration of a surface, especially the land surface or seafloor, including its elevation, relief, and features; shape of the land.

Water Chemistry

The study of the chemical compositions, properties, and reactions of water, especially its behavior in natural and polluted environments.