How can we "see" the layers of the Earth?
A CAT (computed axial tomography) scan animation is included because seismic tomography is often compared to CAT scans. Both techniques have an energy source (seismic tomography uses the energy generated from earthquakes; CAT scans use x-ray energy) and a receiver (seismic tomography uses seismograph stations; CAT scans use comtuters) that records the data. In this animation we simplify things and make an Earth of uniform density (isotropic; constant velocity sphere) with a slow zone that we image as a magma chamber for simplicity. For reference, the Earth figures below show the difference between our simple animation and a body with changes in rock type and temperature that cause the seismic waves to refract and bend when transmitted between different rock compositions.
Seismic tomography is compared to a CT scan
- Both use energy source
- Both have receivers
- Both record the data