... They rise an average of 4,572 meters (15,000 feet) to reach sea level from their base on the sea floor with the highest (Mauna Loa) climbing an additional 4,170 meters (13,680 feet) above sea level. As shield volcanoes , they are built by thousands of accumulated lava flows growing no more than 3 meters (10 feet) at a time to form a broad, gently sloping, flat domed volcanic cone. ... A'a Lava Flow, Hawaii . ... This flow is about 4 meters (13 feet) thick. ... Pahoehoe Lava Flow, Hawaii . ...