how were volcanoes formed ?
http://www.windows2universe.org/earth/interior/volcano_formation.html
thnk u
Volcanoes are formed through a process known as volcanic activity. This activity occurs when molten rock, or magma, rises to the Earth's surface. Here's how it happens:
1. Plate Tectonics: Volcanoes are mainly found along the boundaries of Earth's tectonic plates. These plates are huge chunks of the Earth's crust that float on the semi-fluid layer beneath them. When these plates collide (convergent boundary), move apart (divergent boundary), or slide past each other (transform boundary), it can create the conditions for volcanic activity.
2. Subduction Zones: One common type of volcanic activity occurs in subduction zones, where one tectonic plate is forced beneath another. As the subducting plate sinks into the Earth's mantle, it generates extreme heat and pressure. The heat causes the overlying plate to partially melt, forming magma.
3. Magma Chamber: The magma rises due to its lower density compared to the surrounding rocks. It collects in a reservoir called a magma chamber. This chamber can be located a few kilometers beneath the Earth's surface or sometimes even deeper.
4. Eruption: When the magma accumulates and grows in the magma chamber, the pressure builds up. Eventually, the pressure becomes too great to contain, and the magma finds a way to escape to the surface. This release of pressure leads to an eruption, where the magma, gases, and volcanic ash are expelled.
5. Types of Volcanic Eruptions: Volcanoes can have different eruption styles. Some volcanoes have explosive eruptions, characterized by powerful blasts and the ejection of ash and pyroclastic material (fragments of rock and magma). Other volcanoes have more effusive eruptions, where lava flows out gradually instead of being ejected explosively.
It's important to note that volcanoes can also form within tectonic plates, known as intraplate volcanism, but the exact mechanisms are still a topic of scientific research. By studying these processes and monitoring volcanic activity, we can better understand how volcanoes form and predict their behavior.