Magma and lava are both geographical features of a rapidly changing earth. Magma is the source from which igneous rocks are formed. It is usually molten or semi-molten. However, the biggest differentiating feature of magma is that it is found beneath the earth's surface. It is essentially part of the mantle that has escaped to the surface because of the presence of cracks in the crust of the earth. It is the plastic material on which the tectonic plates float and move.
Magmatism is not only found on our planet; it has also been discovered on other planets and even some satellites. Magma is also a repository of precious crystals and gas bubbles. These gas bubbles contain some very poisonous gases, and if inhaled, they can also cause death. When magma escapes to the surface of the earth through volcanic activity, these gases and the lava flow can cause immeasurable damage to society and civilisation. On the other hand, volcanic activity is also responsible for life-sustaining minerals and nutrients introduced to the soil due to volcanic explosions.
Magma is stored near the surface of the earth in magma chambers. These magma chambers are located mainly in subduction zones, continental rift zones, mid-ocean ridges and hotspots. During their rest in magma chambers, the magma may change in its composition due to crystallisation. This happens because of the lower temperature near the earth's surface compared to the mantle region. Pure magma is also contaminated by the melting of the crust when it comes in contact with magma chambers.
The major source of magma's release through to the surface of the earth are volcanoes. Volcanoes are hills or mountain-like structures on the surface of the earth that have an active connection to the magma chambers. Volcanoes may be active or dormant. Active volcanoes show recent and fresh signs of volcanic activities. Dormant volcanoes may look innocuous, but they may become active at any time, causing a sudden volcano eruption. These eruptions are responsible for the loss of thousands of lives.
Magma is a constant danger when drilling the earth's surface, for it can be encountered abruptly and can lead to loss of equipment or lives. Such incidents have indeed happened in Iceland and Hawaii.
Lava, on the other hand, is similar in composition to magma but the biggest differentiating factor that sets it apart from magma is that it is the part of the magma that has been expelled to the surface of the earth. The temperature of lava ranges from 800 to 1,200°C. The term 'lava' is also sometimes applied to the rock that forms after the lava has cooled.
Lava is found primarily on the earth's surface, and as a result, it is free to move. The movement of lava on the surface of the earth is described by the term 'lava flow'. It is the result of a process called 'effusive eruption'. Effusive eruption happens when the lava is expelled continuously from the crust vis a subterranean duct. It is much slower and chaotic than an explosive eruption, where the lava is expelled at a very high velocity.
Lava is at times 100,000 times more viscous than water. This viscosity is similar to ketchup that we use to dress our food. But lava can travel a great distance before it is solidified completely. This happens because when lava is exposed to the air on the earth's surface, it develops a thin outer crust that keeps the inner lava from cooling rapidly.
The words lava and magma originate from Latin and Greek, respectively. Lava originates from Latin' labes', which means a fall or a slide. On the other hand, the word magma comes from the Greek word 'magma', which was used to refer to 'a thick unguent'. An unguent is a thick paste that is used to treat injuries of the skin.