[COEXERJ145]

I wonder if that was caused by longer wavelengths traveling faster through the earth?

Most likely. Certain seismic waves travel faster than others.

[capitan_refugio]

When you talk about monitoring very large earthquaks, like this one, from stations all over the world, there are a variety of wavepaths that need to be considered. some of the measurements are from waves that have traveled through the core of the earth, reflecting and refracting off of the differnet layers.

The P-waves (compressional waves, like a sound wave) can travel through both solids and non-solids (like the molten outer core). S-waves (shear waves) can only travel through solids, so wave path solutions "image" the boundary layer of the outer core. It will take several days of computing to sort out all of the data.