Final answer:
Volcanic activity and eruptions involve the rise of magma, which becomes lava upon reaching the surface, forming geological structures and layers that can be hazardous.
Step-by-step explanation:
When discussing volcanic eruptions, it is essential to understand the terms magma, lava, layer, and eruption. Magma is molten rock that resides beneath the Earth's surface, which can rise up when tectonic processes, such as plate boundary movements or mantle plumes activity, decrease the pressure or add heat to the mantle material, causing it to melt. When magma reaches the Earth's surface, it is then called lava, forming various geological structures depending on its viscosity and eruption style. Lava can solidify into distinct layers over time, giving us insight into the geological history of the planet. An eruption is a violent release of magma and gases from within the Earth, posing significant hazards to life and climate. Scientists employ a variety of tools to determine the depth of these layers, including seismic surveys, gravity measurements, and magnetotelluric imaging, to understand Earth's interior.