Volcanoes are ranked as one of the most powerful natural phenomena observed on Earth. A volcano offers an escape route for the molten rock stored in the depths of the Earth to come up to the surface. Eruptions can either be explosive or quiet, and they have been witnessed in different parts of the world. Geologists have studied this phenomenon for centuries, helping people grasp information about them. According to the nomenclature associated with volcanoes, there are differences between lava and magma.
Composition Of The Earth's Lithosphere
The Earth is scientifically subdivided into three broad categories which include the core, mantle, and crust.
- The core: The core accounts for about 35% of the total mass of the Earth.
- The mantle: The mantle occupies nearly 68% of the mass of the Earth. It stretches to estimated depths of 1802 miles, and it is made up of silicate rocks which have high magnesium and iron content in comparison to the crust. The mantle is mostly solid although high temperatures result in pockets of molten rock. T
- The crust: Living things inhabit the crust, which is cool and supports life. The crust accounts for less than 1% of Earth's mass consisting of both continental and oceanic crust.
The crust feature pieces of tectonic plates which shift in relation to each other. The interactions of the plates trigger volcanic activity and also mountain-formation. Plates can either move at the transform, divergent, or convergent boundaries. When the plates move at different boundaries, mantle material gets a chance to push up and cause the molten rock to emerge on the surface. The molten rocks present numerous risks to the living things on the crust.
What Is Magma?
The term magma is obtained from Greek word which means "thick unguent" and is used to refer to a viscous material used for lubrication or ointments. Magma constitutes molten or partially-molten rock as well as volatiles, crystals, liquefied gases, and water. It also has other elements including magnesium, aluminum, calcium, potassium, and iron. Magma forms in the depths of the Earth within the magma chambers beneath the volcano. It majorly forms in continental rift regions, subduction zones, and mid-ocean ridges as well as hotspots.
Magma's temperatures range between 700 to 1600 degrees Celsius. As magma travels up, the temperatures drop which may cause it to solidify before it gets to the surface. If it accumulates in a chamber near the surface it may explodes to the surface to form a volcano, and subsequently flow outwards to the surface. If the magma fails to create a volcano, it crystallizes within either the mantle or crust to what is called a pluton. In both scenarios, much of the magma ultimately cools and forms igneous rocks. Magma also exists in other terrestrial planets other than Earth including Mars, Mercury, and Venus and also many moons such as the Earth's moon.
What Is Lava?
Once magma gets to the Earth's surface and erupts from a volcano, it is officially known as lava. The lava is observed as a red hot liquid spewing out of the cracks in the Earth's crust. The term "lava" is derived from the Italian word label which translates to "slide" or "a fall." The word was apparently first used in association with a volcanic activity by Francesco Serao who noted down a short account after observing the eruption of Vesuvius from May 14 to June 4, 1737. Lava is predominantly composed of silicate minerals mainly micas, feldspars, amphiboles, olivine, quartz, and pyroxenes. Three chemical types of igneous rocks that form lava flows once erupted have been identified. Felsic lavas typically contain calcium, silica, potassium, sodium, and aluminum, elements which result in the lava's high strength and viscosity. The lava can erupt at temperatures between 650 and 750 degrees Celsius, and they are highly viscous, and they mostly fragment as they extrude. Intermediate lava is richer in iron and magnesium and lower in silica and aluminum. The lava is hotter at 750 to 950 degrees Celsius, and they are less viscous. Mafic lava is rich in ferromagnesian, and they typically erupt at temperatures over 950 degrees Celsius.
The lava has high magnesium and iron content and lower quantities of silica and aluminum. This combination results in a lower viscosity for mafic lava. Ultramafic lava includes komatiites which have more than 18% magnesium oxide and are believed to erupt at temperatures reaching 1,600 degrees Celsius. The content of lava dictates its behavior more than the temperatures of its eruption. The thinnest lava flow can move downhill for many miles and create a gentle slope. Thicker lava on the hand remains around a volcanic vent, and the thickest ones do not flow and instead pile up on a volcano's throat. Lava flow results in the formation of distinct landforms as well as topographical features. Volcanoes are the main landforms created by lava eruptions. Other landforms include spatter and cinder cones, lava domes, kīpukas, lava fountains, lava tubes, lava deltas, and lava lakes. Lava damage property along their path and the phenomenon has been known to destroy towns such as Kalapana in Hawaii in 1990 during the eruption of the Kílauea volcano. Another eruption of Kílauea had destroyed the towns of Kapoho and Koae in January 1960.
Casualties of lavas are rare because flows are typically slow enough to give time for people and animals to move away although this depends on the viscosity of particular lava. However, deaths and injuries have been reported because they moved near the flow or their escape path was cut off or rarely because the lava flow moves too fast. Deaths blamed on volcanoes often have a different cause such as explosions triggered by the interaction of water and lava flow, volcanic ejecta, poisonous gases, and lahars.
Differences Between Lava And Magma
Although lava and magma are sometimes used interchangeably, there is a significant difference between the two concepts. Magma gives rise to lava as lava simply defined is magma that reaches the earth's surface through volcanoes and other vents. Magma, on the other hand, is melted rock stored in the Earth's crust.