The North Arch volcanic field has been the site of voluminous lava effusion and the formation of shallow magma chambers which gave rise to pit craters when they collapsed. Despite the great depth of the North Arch volcanic field, traces of explosive eruptions has been found there such as steep and low volcanic cones and deposits from fire fountaining; the formation of bubbles from volatile substances in the magma and processes involving supercritical fluids and magma-water interaction are probably involved in the explosive volcanism there.