Hotspots and seismic waves

What is a hotspot?

- A small area of the Earths crust where an unusually high heat flow is associated with volcanic activity.

Example: the Hawaiian Islands

Intense radioactivity in the Earths interior creates a plume from the asthenosphere.

Pushes upwards; the pressure drops and the rock becomes molten, melting and pushing through the crust above.

Lies under a fixed position of the tectonic plate.

As the plate moves upwelling lava creates a steady succession of new volcanoes that migrate along with the plate

The plume also eats into or melts the plate above, so that the thickness of the crust at this point is much smaller than average

These domes or plumes of rock can be up to 1,000 km across.

Earthquakes

1) shallow focus (0-70km)

2) Intermediate (70-300)

3) Deep ((300-700)

Seismic Waves

Sesimic waves radiate from the focus (like ripples from a stone being thrown into…