Volcano:

A volcano is a fissure in the crust of the earth through which gases, lava, and volcanic ash can escape. Liquid magma with dissolved gases rises through fissures in the Earth’s crust beneath a volcano. Pressure falls as the magma rises, allowing the gases to form bubbles. While lava with a high silica level is more viscous, lava with a low silica content is less viscous.

Volcanoes form when material warmer than its surroundings escapes from an interior of a planet or moon. The release of this material triggers an eruption, which can be explosive, propelling material high into the air, or it can be calmer, causing the material to flow in gentle streams.  

Causes: Volcanoes occur when material from a planet or moon’s interior is ejected onto the surface with a temperature significantly higher than its surroundings. When a volcano erupts, the erupted material may be liquid rock (called “lava” on the surface and “magma” underground), ash, cinders, or gas. The following are three reasons magma might rise and cause an eruption on Earth’s surface:

• Magma can rise when pieces of Earth’s crust called tectonic plates slowly depart from each other. In order to fill the space created by it, the magma rises up. Volcanoes can form underwater when this happens.
• These tectonic plates also raise magma when they move toward each other. A large portion of the Earth’s crust can be displaced deep into its interior if this occurs. Melting crusts and magma rise from high pressure and heat.
• Magma can also arise from hot spots. Magma is heated in these regions, which makes it less dense. The magma will rise when it’s less dense. Each of the reasons for rising magma is different from the other, but each can form volcanoes.

Effects:

Positive Effects: 

• Tourists flock to volcanic areas because of the dramatic scenery they create. This brings economic benefits to an area.
• Lava and ash during eruptions provide the soil with nutrients that create very fertile soil. As a result, agriculture is possible.
• There are opportunities for generating geothermal energy on the Earth due to the high levels of heat and activity.

Negative Effects: 

• Many lives can be lost due to a volcanic eruption.
• An eruption of volcanic ash can produce mudflows that move fast when mixed with rainwater or melting snow. These flows are known as lahars. As a result of lava flows and lahars, settlements can be completely destroyed as well as woodlands or arable land.
• It is possible to destroy and change human and natural landscapes forever.

A variety of rapidly moving hazards, such as flying debris, hot gases, lava, and mudslides, can be produced by volcanoes. As far as 100 miles away from an eruption, airborne and deposited ash can have a substantial influence. Breathe through your emergency mask or place a moist cloth over your mouth and nose whenever there is ash present. Put on goggles to protect your eyes. A long-sleeved shirt and long-leggings are also advised because ash may be hot or otherwise irritate the skin.