Why does hawaiian volcano lava flow thin and fast?

Answer 1

Hawaiian lava is composed of basalt. The mineralogy of basalt is (typically) calcium-rich plagioclase feldspar (Bytownite to Labrodorite) and pyroxene. Olivine can also be a significant constituent. Feldspar has a 3-D framework but pyroxene is a single chain feldspar and olivine is individual silica tetrahedra connected by iron, magnesium and calcium ions. Pyroxenes and olivines offer little resistance to flow, thus making basalt very fluid.

Answer 2

Hawaiian lava contains low amounts of silica. The more silica the lava has, the thicker it is and the slower it will flow.