Detectors around the Earth record P-waves but no S-waves along paths that would pass through the outer core. P-waves are also strongly refracted at the core boundary.
Which conclusion is supported by both observations?
The outer core is solid and wave speed changes at its boundary.
The outer core is liquid and wave speed changes at its boundary.
The outer core is liquid and wave frequency changes at its boundary.
The outer core is solid and wave frequency changes at its boundary.