  We have investigated uniaxial pressure effect on superconductivity of pure
Sr2RuO4, whose intrinsic superconducting transition temperature Tc is 1.5 K. It
was revealed that a very low uniaxial pressure along the c axis, only 0.2 GPa,
induces superconductivity with the onset Tc above 3 K. The present results
indicate that pure Sr2RuO4 has two superconducting phases with Tc = 1.5 K and
with varying Tc up to 3.2 K. The latter phase exhibits unusual features and is
attributable to anisotropic crystal distortions beyond the elastic limit.
