plate-boundaries

• Explosive eruptions occur when gas bubbles expand rapidly due to decreasing pressure as lava rises towards the surface.
• Volcanic eruptions can be explosive or effusive, depending on the viscosity of the magma.
• The Pacific Ring of Fire is an area where many volcanoes are located.
• The most explosive volcanic eruption ever recorded was Mount Tambora, Indonesia (1815).
• Volcanoes can be classified based on their shape or type of activity.
• Shield volcanoes are broad, gently sloping mountains formed by repeated effusive eruptions that build up layers of fluid basaltic lava flows.
• The type of volcano is determined by its location along the subduction zone.
• A stratovolcano has steep sides with alternating layers of ash and rock fragments.
• Plate tectonics explains why there are so many active volcanoes around the edges of continents.
• An example of a stratovolcano is Mount Fujiyama in Japan.
• Shield volcanoes have gentle slopes and are built up by repeated flows of fluid basaltic lava.
• There are three types of volcanoes based on their shape: shield volcanoes, composite volcanoes (stratovolcanoes), and cinder cone volcanoes.
• Mount Pinatubo, Philippines (1991) had one of the largest volcanic eruptions since Krakatoa (1883), with ash reaching over 40 km into the atmosphere.
• Composite volcanoes consist of alternating layers of hardened lava and pyroclastic material.
• Stratovolcanoes have steep sides with alternating layers of ash and rock fragments from explosive eruptions.
• Lahars are mudflows that form during volcanic eruptions.
• Shield volcanoes have gentle slopes and are formed by fluid basaltic lavas that flow easily from fissure vents.
• Cinder cone volcanoes form from small amounts of ash and cinders ejected during explosions.
• Cinder cone volcanoes have steep sides and a small summit crater filled with cinders and ash.
• Ash from Mount St Helens, USA (1980) fell out of the sky like snow.
• Cinder cones form when hot gas and ash rise into the air during an eruption and solidify as they cool.
• Stratovolcanoes have violent explosions caused by gas bubbles expanding as they rise through magma.
• Lava domes are formed when thicker, more viscous lava rises to the surface and forms a dome-shaped structure.
• Cinder cones form when hot gases carry small pieces of solidified lava into the air, which then fall back to earth around the vent.
• Subduction zones occur where one oceanic plate dives beneath another at a convergent boundary.
• Stratovolcanoes are tall, conical volcanoes made of alternating layers of hardened lava and pyroclastic material.
• Lava domes are formed from thicker, more viscous lava that cools slowly near the surface.
• At subduction zones, magma rises from the mantle to form new crust above the descending plate.
• Mount St Helens was an explosive volcanic eruption in Washington State in May 1980.
• Stratovolcanoes are tall, conical mountains made of hardened lava and ash.
• Pyroclastic flows occur when hot gases from magma mix with water vapor to form steam, which then explodes outwards.
• Volcanoes can be classified based on their shape and composition.
• Melting occurs when water released during subduction reacts with rocks in the overlying plate, causing them to melt.
• There were two types of eruptions at Mount St Helens - phreatomagmatic (explosion) and pyroclastic flow (hot gas).
• Mount St Helens in Washington State, USA, was an explosive volcanic eruption on May 18th, 1980.
• Cinder cones are small volcanic mountains formed from piles of loose rocks ejected during eruptions.
• The most recent major eruption was from Mount St Helens in Washington State, USA, in 1980.
• The eruption of Mount St Helens in Washington State, USA (1980) was caused by an earthquake that triggered a landslide down the side of the mountain, which then led to the eruption.
• Volcanoes can be classified into different categories based on their size, shape, and composition.
• Volcanoes can be found at constructive plate boundaries where new crust forms as magma rises from below.