What is seismic tomography of the deep Earth mantle?

Seismic tomography is a geophysical imaging technique that uses waves from earthquakes or explosions to map the subsurface of the Earth. By comparing wave arrival times and property changes across different locations, scientists build velocity models to reveal structural and thermal variations. In the deep mantle, these tomographic assays have successfully identified massive features such as large low-shear-velocity provinces near the core-mantle boundary.

What we know

• Seismic tomography images the Earth's subsurface by analyzing modifications to seismic waves generated by earthquakes or man-made explosions. [1, 2]
• Tomographic models are typically seismic velocity models that geoscientists interpret as structural, thermal, or compositional variations. [2, 5]
• Seismic tomography assays of the deep Earth reveal characteristic slow shear wave velocities in large low-shear-velocity provinces located just above the outer core. [3, 4]
• Different types of seismic waves, including P, S, Rayleigh, and Love waves, are utilized depending on the geologic setting and required resolution. [2]

Still open

• The exact nature, origin, and geodynamic effects of large low-shear-velocity provinces remain relatively mysterious.

Where to go next

• a case in pointWhat are large low-shear-velocity provinces?
• whereWhat lies at the core-mantle boundary?
• how it workedHow do P and S seismic waves travel through the Earth?
• the bigger pictureHow does ge geophysics map subsurface structures?
• what followedHow do core-mantle processes affect Earth's magnetic field?
• an unexpected connectionHow are deep mantle structures named after plate tectonics pioneers?The two massive low-velocity provinces in the deep mantle, Tuzo and Jason, are directly named after Tuzo Wilson and W. Jason Morgan due to their foundational contributions to plate tectonics.

Sources

• [1]seismic tomography (Wikidata Q1850768) · CC0 1.0
• [2]Seismic tomography · CC BY-SA 4.0
• [3]Large low-shear-velocity provinces · CC BY-SA 4.0
• [4]Core–mantle boundary · CC BY-SA 4.0
• [5]Seismic velocity structure · CC BY-SA 4.0