Planet Earth never ceases to surprise us. Within the past month we've discovered a canyon and a volcano, both of which are longer and larger than the previous record-holders in those categories.
The first record-breaker, known as the Greenland Grand Canyon, remained unknown until last month because it lies beneath Greenland's ice cap. It was discovered using ice-penetrating radar and is over 750 kilometers (466 miles) long, a bit less than twice the length of the Grand Canyon in Arizona (at 446 kilometers [277 miles] long. It's also up to 800 meters (2,600 feet) deep, and up to 10 kilometers (6 miles) wide. (Though Arizona's Grand Canyon is both deeper and wider in places.)
(The longest canyon in the world is actually the Yarlung Tsangpo Grand Canyon in Tibet, which is a bit longer than the Grand Canyon in Arizona, although I couldn't find solid numbers on how much longer. It is also the worlds deepest canyon, with a deepest point of 6,009 meters [19,714 feet].)
The second record-breaker is a volcano located on the Pacific sea floor about one-third of the way from Japan to Hawai'i. This humongous edifice goes by the name of Tamu Massif, and while it has been known since at least 1993, it was previously thought to be multiple volcanoes due to its incredible size. On it September 5th it was announced by scientists studying it that it was actually a single volcano, which made it the largest volcano on earth.
This announcement was of interest to me, since I live on the flank of what was previously thought to be the largest volcano in the world – Mauna Loa. When we say “largest,” we should be sure to define what we mean. Tamu Massif is larger in surface area than Mauna Loa, but shorter in height. Mauna Loa has a surface area of 5,000 square kilometers (about 1,900 square miles), and rises an incredible 9,170 meters from the sea floor (30,085 feet). Tamu Massif, by contrast, rises a mere 4,460 meters (14,620 feet) from the sea floor, but has a surface area of 260,000 square kilometers (100,000 square miles), approximately the size of New Mexico.
Despite its height, the summit of Tamu Massif is still 1,980 meters (6,500 feet) below the surface of the Pacific Ocean. This is because it has an incredibly gentle slope (it's also long extinct, so it's not getting any higher). Mauna Loa has slopes that don't exceed an average inclination of 12 degrees, but Tamus Massif's sides have an average inclination of no more than a single degree.
Tamu Massif has some interesting similarities with a volcano on Mars called Alba Mons. Since “Everything's Bigger on Mars” when it comes to geological features, it's no surprise that Alba Mons is larger than Tamu Massif. In terms of surface area it stretches for a good 1,000 by 1,500 kilometers (620 by 930 miles). Like Tamu Massif, it too has incredibly gentle slopes of 0.5 degrees on average.
It's not surprising that these incredible features of our world could remain hidden for so long, given their locations under ice cap and ocean. It's definitely exciting that we're starting to discover them. Who knows what else there is out there waiting to be discovered? A hui hou!