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Roger Weller, geology instructor regional geology planetary gems
The Hawaiian Hotspot
At first glance, lava and magma would not seem to have much of an impact on the world. Sure, every once in a while a volcano such as Mount Saint Helens will erupt and throw everybody out of their comfort zone for a few minutes, but unless we ourselves live at the bottom of an active volcano, lava and magma have almost no significance to us. Most people know little about lava and magma besides the fact that it’s hot and comes out of volcanoes from time to time;; (and to run away from it when this happens). For this reason, magma and lava are seen as unimportant: they would seem to have no impact on everyday life, so who cares about them? If one has ever so much as set foot on an island such as Hawaii or Iceland or even taken a trip to visit Yellowstone national park, this notion of magma’s unimportance is drastically wrong. Magma/lava, in the form of “hotspots,” does have an impact upon everyday life because it is responsible for the world as we know it. Hawaii is recognized as one of the world’s paradises, and the Hawaiian Hotspot is directly and solely responsible for its creation and existence
What is a Hotspot?
In order to understand what a hotspot is, it is first necessary to have a cursory knowledge of the workings of Earth’s interior. The Earth contains three layers: crust, mantle, and core. These levels become progressively and extremely hotter. The majority of Earth’s volume is the mantle region, and consists entirely of magma. The crust is simply a cooled version of the mantle. The magma that lies below the crust and the crust itself have little effect upon each other because, while heat is applied from below, cooling is applied from above. By and large, the crust region is in a state of equilibrium. A hotspot is simply a place in which this equilibrium is thrown off by an irregularly hot section in the mantle. Geologists theorize that this is caused by an excessively hot “stream” of hot mantle coming up from the Earth’s core that is called a “mantle plume.” This mantle plume creates a small and very regional area that experiences advanced volcanism. And this area is called a “hotspot.”
History of Hawaiian Hotspot
When a hotspot and its ensuing eruptions occur in an area covered by ocean, the
result is the formation of islands. Lava erupts and is cooled, and then new lava
erupts on top of the old and is once again cooled until it protrudes from the
water in the form of a “shield” volcano. The “Hawaiian Hotspot,” is a hotspot
that is responsible for the formation of the Hawaiian Islands. While it
currently lies under the youngest and most recently created Hawaiian island of
Hawaii (Kona), this was not always the case. While the hotspot itself does not
move from its position in the mantle region, the tectonic plates that make up
Earth’s lithosphere do. Thus, different parts of the tectonic plates approach,
pass over, and ultimately leave hotspot areas.
The Hawaiian Hotspot, specifically, is an interesting case study in plate
tectonics. As differing parts of the tectonic plate have passed over the
hotspot, it has left a “chain” of islands. Where we find these islands indicates
where the hotspot used to reside. While there are only eight “main islands” that
we know as the state of Hawaii, these eight islands are only those which are
visible. There are literally countless islands in this chain submerged
underwater. In addition, distant islands such as Midway were long ago created by
the Hawaiian Hotspot. All in all, the Hawaiian Hotspot is responsible for the
creation of islands that span a distance of 1500 miles. By tracing the path of
these islands, we can directly trace the path of the tectonic plate over the
Hawaiian Hotspot, meaning we can see exactly the directions in which it has
traveled over many thousands of years. This specific tectonic plate has usually
a northwestern direction, but originally began drifting almost due north.
Today, a new Hawaiian island is forming under the auspices of the Hawaiian
Hotspot. Named “Loihi,” Geologists estimate that it will break the surface of
the water within 10,000 and 100,000 years.
Effects of Hawaiian Hotspot
The Hawaiian Hotspot has had and continues to have effects on the surrounding world. Obviously, the creation of an underwater “mountain range” is one of these effects. Most people consider this to be a pleasant effect. With the good, however, comes the bad. Geologists are currently monitoring a “rift” zone on the island of Kona where extruding lava is forcing its way to the surface and pushing apart two regions of the island. These geologists fear that is only a matter of time until this rift simply collapses into the ocean. Such a collapse would create a tsunami of gargantuan proportions and it is estimated that tidal waves hundreds of feet tall would obliterate seaboard cities such as Los Angeles.
The Hawaiian Hotspot is truly fascinating and deserves the intense interest that it generates. It is evidence of both the power and patience of nature. It is evidence that a destructive force to be feared can create something beautiful and serene. It is evidence of the inherent and mindboggling complexity of the world and universe around us. Ultimately, it reminds us of the duality of nature: permanent, yet ephemeral.
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