Nature & living things · Earth & places

Hawaii's next island is already taller than Mount St. Helens

Off the southeast coast of the Big Island sits a submarine volcano that most people have never heard of, partly because it only got its current name in 2021. For decades it was called Lōʻihi, meaning "long," after its elongated shape, but Hawaiian cultural researchers found an older name in 19th-century chants describing it as a glowing child of the ocean god Kanaloa, and officials adopted that instead. The volcano sits on the flank of Mauna Loa and is the youngest link in the long chain of hotspot volcanoes that built the Hawaiian islands. Its summit is still nearly a thousand meters underwater, and at roughly 400,000 years old it is expected to keep growing for tens of thousands more years before it might eventually break the surface and become new land.

For most of the twentieth century scientists weren't even sure it was active; early surveys assumed it was an old, dormant feature simply carried into place by the spreading seafloor. That changed after a 1970 earthquake swarm, and especially after a dramatic 1996 episode when thousands of quakes in a few weeks caused part of the summit to collapse, swallowing a hydrothermal field called Pele's Vents and creating a new crater known as Pele's Pit. Researchers who rushed out on follow-up expeditions found scalding vent fluids, clouds of sulfide, and fresh lava, confirming an eruption had occurred just before the collapse. A seafloor observatory called HUGO was installed the next year to send real-time data back to shore, though a broken cable silenced it within a year, and it was eventually pulled up in 2002. Since then the volcano has stayed relatively quiet, punctuated by occasional moderate earthquake swarms, including one in 2005 that produced its largest recorded tremor.```) the pattern of low background seismicity interrupted by bigger episodic swarms has continued into recent years.

What makes the place scientifically interesting isn't just its geology but what lives on it. Its hydrothermal vents, rich in carbon dioxide and iron but poor in sulfide, create unusual conditions that favor iron-oxidizing bacteria rather than the sulfide-eating microbes typical of other vent systems, and researchers have run dedicated expeditions since 2006 just to study these organisms. Thick microbial mats coat much of the collapsed crater, and the surrounding waters host some unusual animals too, including a shrimp and a tube worm found nowhere else, though surveys after the 1996 collapse failed to relocate them, leaving their fate uncertain. Fish species new to Hawaiian waters have also turned up on its slopes. Together the seismic record and the biology have made this obscure seamount a long-running natural laboratory for watching a volcano, and the life that depends on it, take shape from the deep ocean floor.

During the 1996 swarm of 4,070 earthquakes, a vent field called Pele's Vents collapsed entirely into itself, leaving a pit that had to be given a new name.

Read the whole of Kamaʻehuakanaloa Seamount on Wikipedia

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