Do you like vacationing in Hawai’i – body surfing in the waves, snorkeling in the crystal clear water, or walking along the sand beaches, scanning the ocean for whales? Well you’ll be glad to hear there’s a new Hawaiian island, named Lo’ihi, being created right now!
But don’t start planning a vacation to this new island just yet. It’s still underwater, and scientists predict it won’t grow tall enough to peak out of the surface of the ocean for another 50,000 years!
Where is this new island being formed?
The island of Hawai’i (also called The Big Island); white area represents land above ocean surface; Lo’ihi Island specified by pink rectangle. Courtesy of SOEST (School of Ocean and Earth Science and Technology).
Lo’ihi is located about 35 kilometres off the southern coast of the island of Hawai’i, and currently rises more than 3,000 metres above the floor of the Pacific Ocean, about the height of ten Eiffel Towers, stacked one on top of the other. The island will need to rise an additional 1,000 metres before it reaches the surface of the ocean.
3D image of Lo’ihi. Courtesy of Wikipedia.
The name Lo’ihi is Hawaiian for ‘long’, and refers to the elongated shape of the underwater island, as you can see from the image above. The image shows the ocean floor beneath the ocean surface.
How is the island of Lo’ihi being formed?
The Hawaiian Islands were created millions of years ago by volcanoes. But to fully understand how these islands were created, we need to understand how volcanoes work.
Map of Tectonic Plates of the earth. Courtesy of USGS.
The earth’s crust is made up of large, very thick sheets of rock, known as “tectonic plates”. These plate fit together like puzzle pieces, as you can see in the image above. The plates float over top of a layer of incredibly hot molten rock.
And although you can’t feel it, these plates are constantly moving, very, very slowly, at a distance of only a few centimetres a year. Over millions of years, the movement of these plates has brought the continents closer together, moved them apart, created mountain ranges, and widened and narrowed the oceans, resulting in the configuration of the continents as they are today.
As the plates move, the molten rock from the layer beneath can flow up through cracks in the crust of the earth as lava. When this is repeated over and over again in the same location, the lava builds up layers, forming into a volcano. This is the most common way a volcano is built.
Map of Tectonic Plates of the earth. Courtesy of USGS.
However the Hawaiian Islands are located in the middle of one of these plates (as you can see in the image above), not along the edge, so how did volcanoes develop there?
Volcanoes are also created at “hot spots”, and this is how scientists believe the Hawaiian Islands were created. Hot spots are created where the earth’s crust is thinner than usual, or where the layer of molten rock below the crust is unusually hot. At these locations, molten lava seeps up through the earth’s crust. One of these hot spots exists in the middle of the Pacific Ocean, and it began creating the Hawaiian Islands up to 70 million years ago.
Each time this hot spot volcano erupted, it spewed out an additional layer of lava, building up the sides of the volcano. Over time the volcano can grow above the surface of the ocean, and become an island. While they were being created, the other Hawaiian Islands grew at a rate of about 3 centimetres per year. If Lo’ihi matches this growth rate, it will take tens of thousands of years for it to emerge above the ocean’s surface as an island.
Because the lava flow occurs underwater, the lava forms into “pillow lava”, named due to its shape. The lava ‘pillows” might look soft and fluffy, but they’re solid as rocks! Immediate exposure to water causes the lava to cool and solidify quickly. Some of Lo’ihi’s volcanic flows are no more than a few hundred years old, which is very young in geological time.
Pillow Lava. Courtesy of USGS.
Why are the volcanoes on the other Hawaiian Islands no longer active?
The existing Hawaiian Islands were all created by the same hot spot that is currently creating Lo’ihi. But, as you can see in the image below, there are only three active volcanoes in Hawai’i; two located on island of Hawai’i, and Lo’ihi, which is located just south of the island of Hawai’i. All other volcanoes on the Hawaiian Islands are dormant.
Dormant and Active volcanoes of the Hawaiian Islands.
Additionally, the more northwestern the Hawaiian Islands is located, the older it is. For example the island of Kaua’i is about 5 million years old, while the island of Hawai’i is less than one million years old. In fact, the story of Pele, the Hawaiian Goddess of fire and volcanoes, attributes the creation of the volcanoes in Hawai’i to the goddess. The legend states that Pele first came to the island of Kaua’i, then fled to Oahu, to Molokai, to Maui, and finally to the island of Hawai’i, where she created and lived in the volcanoes on each of those islands. It is believed that she lives at the summit of the active volcano Kilauea on the island of Hawai’i to this day, probably because that is the last island to have active volcanoes. Not coincidentally, the order of the volcanoes that Pele was believed to have created is the order that the islands rose out of the ocean as volcanoes, as the legend was created to explain the birth of the Hawaiian Islands. But why are the older volcanoes no longer active?
Since we know that the islands were formed as volcanoes one by one, and by the same hot spot that is creating Lo’ihi, why are the islands in different locations? Did the hot spot move? No, actually the hot spot has existed in the exact same location for millions of years, but the tectonic plate that glides over top of it has moved. In fact, the Pacific Plate has been moving northwest at a rate of 5 to 10 centimetres each year.
Creation of a volcano over the hot spot. Courtesy of Smithsonian Magazine.
As the tectonic plate moves over the hot spot, the molten lava punches up through the earth’s crust, and begins to create a volcano. The volcano continues erupting, and with each subsequent lava flow it grows taller, building the volcano over hundreds of thousands of years, until it eventually rises above the surface of the ocean as an island. Meanwhile the tectonic plate the volcano sits on continues to move, and eventually it has traveled so far that the volcano is no longer situated above the hot spot. When this happens the supply of lava is cut off from the volcano and it stops erupting, and finally becomes dormant. This is why the older volcanoes are no longer active, as they are no longer being fed lava from the hot spot.
Eventually the hot spot will once again penetrate the earth’s crust in a new location on the tectonic plate, and a new Hawaiian volcano is born! This is the way all the Hawaiian Islands were formed, and are still building to this day.
In this article we have discussed how the new Hawaiian Island of Lo’ihi was born, and is currently growing from lava being fed from a volcanic hot spot on the floor of the Pacific Ocean. Eventually the volcano will grow tall enough to break the surface of the ocean, and become another tropical island. But one day the tectonic plate it sits on will have moved away from the hot spot, as all Hawaiian Islands do, and the volcano will become dormant.
References
Loihi Seamount: The New Volcanic Island in the Hawaiian Chain. (n.d.). Retrieved March 27, 2017, from http://geology.com/usgs/loihi-seamount/
The Formation of the Hawaiian Islands. (n.d.). Retrieved March 27, 2017, from https://www.soest.hawaii.edu/GG/HCV/haw_formation.html
Main Hawaiian Islands Multibeam Bathymetry and Backscatter Synthesis. (n.d.). Retrieved March 27, 2017, from http://www.soest.hawaii.edu/HMRG/multibeam/products.php
Hotspots [This Dynamic Earth, USGS]. (n.d.). Retrieved March 27, 2017, from https://pubs.usgs.gov/gip/dynamic/hotspots.html#anchor19620979
Evolution of Hawaiian volcanoes. (2017, March 22). Retrieved March 27, 2017, from https://en.wikipedia.org/wiki/Evolution_of_Hawaiian_volcanoes
Lōʻihi Seamount. (2017, March 25). Retrieved March 27, 2017, from https://en.wikipedia.org/wiki/L%C5%8D%CA%BBihi_Seamount
Rambo, R. (1970, January 01). The Hawaiian Islands (and How the Hawaiian Islands Were Made). Retrieved March 27, 2017, from http://hawaiiislandvolcanoes.blogspot.ca/2011/04/hawaiian-islands-and-how-hawaiian.html
Wayman, E. (2011, December 01). What We’re Still Learning About Hawaii. Retrieved March 27, 2017, from http://www.smithsonianmag.com/travel/what-were-still-learning-about-hawaii-74730/
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