SEISMIC WAVE SPEED (VELOCITY) DEPENDS ON ELASTIC CONSTANTS (MODULI) AND DENSITY

- BULK MODULUS - LARGER IS HARDER TO COMPRESS

- SHEAR MODULUS - LARGER IS HARDER TO SHEAR

- DENSITY

COMPRESSIONAL (P) WAVE SPEED VP DEPENDS ON BOTH MODULI

SHEAR (S) WAVE SPEED VS DEPENDS ON SHEAR MODULUS

P WAVES TRAVEL FASTER (ABOUT 1.7X ) THAN S WAVES

S WAVES CANNOT TRAVEL THROUGH LIQUID ( = 0) LIKE OUTER CORE