Mauna Loa: The World’s Largest Volcano

Tuesday, 8th November 2011 by

Hardcore Google Sightseeing readers may remember all the way back to 2005 and the third month of the site when we looked at the volcanoes of the Big Island of Hawaii. With the wealth of new hi-res satellite and Street View imagery over the past few years, it’s time to return to the Big Island and explore the world’s largest volcano.

Covering an astounding 5,200 km2 (2,000 sq. mi.) Mauna Loa is not only the world’s largest volcano, but is actually the largest mountain by area and by volume on the planet. In fact, when measured from its ocean base, it’s actually higher than Mount Everest! (Update, see this comment for some clarification on this point.)

Mauna Loa has been in a constant state of eruption for the past 700,000 years. Its massive size is due to its nature as a shield volcano; rather than exploding out of the volcano, the lava flows down the sides of the mountain just like rivers, slowly building the mountain higher and higher over time. From above they almost look like army camouflage or an impressionist painting. Some of these old channels are so huge that they cover hundreds of square kilometres as they run all the way to the Pacific Ocean.

Eruptions occur all over Mauna Loa in a rift zone several kilometres long. The summit crater, Mokuʻāweoweo, hasn’t actually erupted since 1984. This has allowed the lava that fills the massive 4.8 x 2.4 km (3 x 1.5 mile) crater to solidify on top, although one can still make out the conduits and fissures from where the lava emerged and probably will again.

Moving further down the rift zone to the southwest, molten-hot lava can be seen erupting out of cinder cones and slowly making its way down the slopes.

Because of the constant streams of new volcanic materials being laid down, much of the slopes are covered in nearly-barren brown and black volcanic rock. Some of this rock is smooth and pillowy, produced by flows known as pāhoehoe, while much of the slopes are covered in jagged, loose and blocky rocks produced by ʻaʻā flows. Despite the rough terrain and near-desert conditions in places, that hasn’t stopped people from building houses directly on top of the blocky old lava channels.

Mauna Loa is also famous as a major centre of scientific research, as the US government operates both a solar observatory and an atmospheric observatory on its slopes near the summit to take advantage of the high altitude and clear air.

Rough and narrow, the road up to the observatories pushes through seemingly endless fields of jagged rock as it climbs up the volcano. Along the way, drivers get an excellent view of the neighbouring volcano of Hualālai in the distance before reaching the observatories at the end of the road.

Since the last major eruption in 1984, Mauna Loa has been rather quiet; the longest recorded quiet period in its history. It’s only a matter of time before another big blast comes along and once again changes the landscape of Hawaii’s Big Island, and with over 100,000 people potentially in its path, you’ll be sure to hear about it when it does.