GMI-Teikoku-M

UCS = 3770e(M ´ 1.65e^–7)

where:

3770 is in psi.

M is P-wave modulus in psi.

This equation is derived from the correlation of triaxial test results on eight volcanic core samples with well logs in a well in northwest Japan. The core density ranges between 2.4 and 2.6 g/cm³. The reported UCS ranges between 8,000 and 18,500 psi.