Week 4 - Volcanos

The Hawaiian Volcano - Kilauea

During a recent trip to the Hawaiian Islands, my family and I had an opportunity to visit the Earth's most active shield volcano, Kilauea. Kilauea is one of five volcanoes that make up the big island of Hawaii. Of course, my children were excited and frightened by this adventure due to the fear of an active eruption occurring while we were staying on the big island of Hawaii. Prior to our visit, I shared some information I had learned over the years in order to ease their minds.

Most volcanoes are found along a divergent or convergent plate boundary. There are two kinds of volcanoes: (1) composite and (2) quiescent or effusive. A composite volcano, such as Mount Rainer in Washington, has more explosive eruptions than that of a quiescent volcano such as Kilauea.
Volcanoes along plate boundaries result in more explosive eruptions due to the higher level of silica make-up and the viscosity of the magma. The higher levels of silica result in faster cooling of the magma and the creation of crystals. The magma is thicker, less fluid, and because the crystals cannot break through the viscous magma, pressure builds, and when it has grown so great, the result is a violent explosion.

The Hawaiian Islands are unique in that they are not located on a plate boundary, rather they are located above a hot spot deep below the Earth. The Hawaiian hot spot is known as the Submarine or Hawaiian Ridge. The ridge is displayed in the image below:

Hawaiian Ridge 

https://geology.com/usgs/hawaiian-hot-spot/

My oldest daughter, asked how would a volcano form if there are not any converging or diverging plates to create friction? I shared that after years of research into the thought of seafloor spreading and plate tectonics by geologists, it was determined, that while the Hawaiian Ridge was in the middle of the Pacific Plate, there was continuous movement of the plates over the fixed hot spot  on the ocean floor, which generates new molten rock over time. The molten rock moves into newly created fissures due to the plate movement which results in a volcanic eruption. 

Kilauea is considered a shield volcano. A shield volcano starts on the ocean floor, as mentioned above. The magma in a shield volcano is made mafic materials such as basalt. Mafic lava is less viscous than the felsic lava found in composite volcanoes. As new mafic magma is formed it flows into already existing magma chambers. As the chambers fill up and pressure is built, fractures in the surface rock are created which allows the release of the lava. As the lava is released, the gases readily escape in a lava fountain. Because the lava is so hot and fluid, it is released in a runny manner and it can flow for days, weeks, months and many miles.

Lava Fountain - Kilauea 

http://www.reservehawaii.com/travelguide/hawaii-volcano-tours-highlight-of-big-island-activities/

Lava flow at Kilauea

http://silentobserver68.blogspot.com/2012/10/hawaiis-big-kilauea-and-mauna-loa.html

Activity in a shield volcano can be predicted by monitoring the summit of the volcano, because as the new molten rock enters into the chambers swelling may occur as the lava pushes against the surface and fractures in the surface form, which is typically followed by the release of the lava. Below is a picture of the craters on top of Kilauea in a non-eruptive state:

Craters at the summit of Kilauea

https://volcanoes.usgs.gov/observatories/hvo/multimedia_uploads/multimediaFile-1878.jpg

While we were in Hawaii, we learned that geologists at the US Geological Survey and Hawaiian Volcano Observatory, had been watching the Kilauea summit closely due to recent increased activity, indicating there was a potential risk of an eruption. Below is a picture of a geologist monitoring the activity in the craters in March of 2018. If you look closely you can see a lava fountain beginning to form in the left corner and a lava stream in the center. 

Activity monitoring of Kilauea 

https://volcanoes.usgs.gov/observatories/hvo/multimedia_uploads/multimediaFile-1874.jpg

Upon our safe arrival home, as we watched the headline news, we came across the new story of a recent eruption of the Kilauea volcano on April 4, 2018. The news link below provides an incredible video of the lava fountains and fluid basaltic lava as it is released. https://www.msn.com/en-us/weather/topstories/lava-bubbles-from-hawaiis-kilauea-volcano/vi-AAvwEzS.

Knowing that the Kilauea has been the most active volcano since 1983 with continued eruptions as recent as this past week, reports by geologists that there is no end in sight, there is a high probability that we will see continued activity from the Kilauea for some time.