 With the widespread availability of geothermal power, and the harnessing of many rivers and waterfalls for hydroelectricity, most residents have access to inexpensive hot water, heating, and electricity.The island is composed primarily of basalt, a low-silica lava associated with effusive volcanism as has occurred also in Hawaii.Iceland, however, has a variety of volcanic types (composite and fissure), many producing more evolved lavas such as rhyolite and andesite.