Submarine Volcanoes

Submarine volcanoes are ruptures on the earth’s surface that are found underwater from which magma erupts. Volcanic activities on terrestrial land are widespread and accessible for study, and as a result, a lot is known about these activities. However, unlike terrestrial volcanoes, very little is known about submarine volcanic activities (Cashman & Fiske, 1991). It is because underwater volcanic activities, especially deep-sea volcanoes, are not easily detectable using hydrophones since water cannot boil as a result of the high pressure (above 218 atmospheres) exerted at the bottom of the sea. The occurrence of volcanic eruptions in shallow waters results in material being thrust to the air (‘Submarine Volcanoes – Crystalinks,’ 2018).

During an eruption in deep-sea volcanoes, the topmost lava comes into contact with seawater and immediately forms as crust. The underlying lava continues flowing into the crust to form a pillow lava (‘Submarine Volcanoes – Crystalinks,’ 2018). A seamount is a submerged mountain that forms as a result of this process. Seamounts build up over time and eventually reach the surface of the ocean to form islands such as the Hawaiian Island (‘Underwater Volcanoes – Universe Today,’ 2018).

The most massive underwater eruption ever recorded was the eruption of Havre Seamount in 2012. Many scientists had somehow missed citing the volcano but managed to get the large floating rock that was generated as a result. The rock covered 400 square kilometers before it dispersed (Dockrill, 2018).

Submarine volcanoes can be classified into two: those created through the slow discharge and bursting of huge lava bubbles and those formed in a quick explosion of gas bubbles. Lava affects marine life and ecosystems differently than gas which is very important to distinguish the two (Cornell, Templeton, & Staudigel, 2016).

Scientists have developed techniques that use sounds and images to identify and differentiate between the two types of eruptions. The technology was used successfully in 2009 to observe the West Mata Volcano erupt in several ways. Video and audio were used to study the sounds made by slow lava bursting and the noises made from the release of hundreds of gas bubbles (Cornell, Templeton, & Staudigel, 2016).

According to Mastin et al., violent eruptions of submerged volcanoes are not just as a result of water mixing with magma. They believe the eruption occurs in two steps: that is, the flow of magma in a channel below the water table followed by the jetting of water through the water surface. This mechanism was evident on 3 April 1977 in Alaska when a hydro magmatic blast was preceded by a lava lake draining and the crumbling of the crater walls.

The knowledge of Seamounts has triggered research on various diverse fields including volcanology, geology, geochemistry, physical oceanography, and marine biology among others. Scientists have come up with theories to explain the impact of submarine volcanoes on, among others, tectonic plate movements, stress on underwater lithosphere and chemical composition of Earth’s mantle.

The active undersea volcanoes provide a favorable habitat for various types of fungi. Fungi of unknown species have been found in multiple seamounts. These include hydrocasts near hydrothermal plumes from the Mid-Atlantic Ridge that is found near the Azores and in Pacific sea-floor sediments. Researchers like Gadanho and Sampaio have discovered yeasts from Atlantic plume waters in 2005 leading to the fact that the deep-sea hydrothermal habitat may contain different types of microbial organisms including both eukaryotes and prokaryotes (Cornell, Templeton, & Staudigel, 2016).

Although the majority of seamounts are extinct, there are many other active submarine volcanoes which scientists continue researching on to be able to understand the way they function. They also try to find new technologies that will make detecting and researching these weird phenomenam easier. Seamounts will continue emerging and may even end up becoming islands which someday humans can live on, just like the Hawaii Islands (Mastin et al., 2004).

Some seamounts are circular or conical with a magma chamber within the volcano. Large seamounts often lie above hot spots, which are sections in the deep mantle associated with plumes of molten rock rising and melting through the overlying tectonic plate to supply magma to seamounts. These plumes have a long lifespan, and they continue to melt through tectonic plates passing over them resulting in a series of volcanoes over time. Examples of Islands that were formed as a result of hot spots include The Hawaiian Islands, the Galapagos Islands, the Azores, and the Cobb-Eikelberg (Mastin et al., 2004).

Underwater volcanoes greatly influence the shape of the ocean floor. The ocean’s lithosphere comes under enormous stress from seamounts resulting in deflections. Most published models estimate stress differences between 2 and 3 kbar per kilometer of deviation with maximum values approaching 10 kbar (Lambeck & Nakiboglu, 1980). The lithosphere tends to be thinner when loads from seamounts are high and thicken with reduced loads. Models have been developed to explain the lithosphere’s flexural rigidity by considering forces from the magma below the ocean (Lambeck & Nakiboglu, 1980).

Observing the activity of active underwater volcanoes, have helped scientists gain a better understanding of the formation, evolution, and composition of large islands such as Hawaii. Studies are however made difficult due to associated high costs as most seamounts form below the oceans’ surface. Their heights also regularly change, growing as a result of repeated episodes of volcano growth and reducing as due to rapid flank collapse. Often, the rates of change are high and make it difficult to make consistent observations. Variations of up to 630 million cubic meters have been recorded for growth and 110 million cubic meters for collapse (Schmincke, 2013).

Seismic swarms are a common phenomena accompanying submarine volcanic eruptions. These earthquakes are have different magnitudes and usually grow stronger as they migrate. Earthquakes rates at less than 2.5 M were recorded to have peaked at 4.4 Metres on El Hierro in 2011 (Schmincke, 2013). Other observations made during this event were a constant vibration, resulting from the fast rise of the magma, changes in the color of the water and hot volcanic bombs hovering on the surface of the ocean. In some cases, the seismic activities resulting from underwater volcanoes reach the dry land and cause tsunamis that result in massive destruction. Coastal regions are at the most significant risk when this occurs (Schmincke, 2013). A tsunami resulting from an underwater explosion back in 1883 was recorded to have caused more than 36000 deaths. The formation and characteristics of the tsunamis formed are influenced by factors such as the amount of flux flowing and the size of the explosion. Currently there are no systems designed to deal with tsunamis that result from activities such as submarine explosions. Studies into this underwater activity may provide further insight into the development of more advanced and capable tsunami warning systems.

Hydrothermal fluids from submarine volcanoes show significant disparity in the levels of CO2 and pH. Some of the vapor emitted recorded high levels of acidity or alkalinity while others had higher concentrations of CO2. These result in variations in the levels of CO2 and acidity in the water significantly influencing aquatic life. A study of The Kolumbo, however, found that the emissions, which are 99% CO2, were trapped inside a lake inside the crater 350 meters below the ocean surface. It resulted in the emissions having no significant impact on the upper 100 meters of the ocean waters (Karatsolis et al. n.d).

Further research has shown that of the CO2 emitted, more than 80% comes from slab sources (Resing et al., 2009). Classification of underwater volcanoes based on their level of hydrothermal activity resulted in 3 groups: strong level, low level, and no action. Strong activity volcanoes are those from which samples taken are concentrated enough to enable identification of the source while concentrations in low activity volcanoes cannot allow for such. Low activity volcanoes are easy to spot, but this gets harder as the activity level continues to diminish (Resing et al., 2009).

Most of the underwater volcanic activity takes place deep in the ocean creating a chain of underwater mountains, some of which grow beyond the surface forming islands. The mid-ocean ridge, which extends for thousands of miles below the ocean, is an example. The spread of tectonic plates can explain the high levels of activity in this region. This area alone is said to have more volcanoes than there are on the dry land. The Pacific Ocean alone is estimated to have over 4000 volcanoes.

On land, volcanoes have given much insight into the dynamics of submarine volcanoes. The later has however had limited research due to factors such as cost and difficulty in making observations under water. Most volcanic activities in the deep ocean often go undetected as well. It is however evident that these underwater activities have a significant impact on the ocean’s ecosystem. Its effect may in some cases be felt on land in the form of tsunamis and earthquakes especially where the activities take place close to the land. It is therefore an important area for more research and study to be done.