sci depart

• it refers to the eruptive and non-eruptive activities that take place in a volcano

  volcanic process
• When the vapor pressure becomes grater than the confining pressure, magma rises toward the surface where the pressure is lower. Consequently, the dissolved gas ia allowed to expand and it forms small gas bubbles, called vesicles, in the magma.
• Vesicles make the magma less dense than the surrounding rock which may allow the magma to move upward. as it gets closer to the surface, the size and number of vesicles increases and exceed the melting volume in the magma, producing a magma foam that can lead to a explosive eruptions.
• During the eruption, volcanic gases in the magma expand and break magma into tiny pieces called tephra.
• true or false

  TRUE 1. if the molten rock is not fragmented by explosive activity, lava flow is oserved
• Volcanologists associate the event with the July 16 earthquake in 1990. With a magnitude of 7.8 that occurred 100 kilometers northeast of the Pinatubo region, landslides and small earthquakes triggered powerful steam emissions that exploded three craters on the volcano.

  The 1993 eruption in the Philippines had global effects, possibly causing drought in the Sahel region of Africa in 1993 and intensifying the destruction rate of ozone, which was exacerbated by the eruption's impact on the region.
• In June 1991, Mt. Pinatubo, a part of the Luzon volcanic arc, erupted after over four centuries of silence. On June 15, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) recorded 19 eruptions, causing a "day without a sun" in the Philippines when huge mushroom-shaped clouds disturbed the stratosphere up to 20 km high.

  Pyroclastic materials and volcanic mudflows (lahar) flowed down Pinatubo's gullies into rivers and heavy ashfalls blanketed the provinces of Zambales, Pampanga, and Tarlac.
• the 1991 cataclysmic plinian eruption of mt. pinatubo was the 2nd largest eruption in the 20th century with a vei rating of 6. ashfall was also recorded in countries cambodia, malaysia, and vietnam
• open https://www.pompeiitours.it/blog/11-amazing-facts-about-mount-vesuvius/ mt. Vesuvius erupted in 79 ad
• Tambora's catastrophic eruption began on April 5, 1815, with small tremors and pyroclastic flows. A shattering blast blew the mountain apart on the evening of April 10
• mt. tambora The most destructive explosion on earth in the past 10,000 years was the eruption of an obscure volcano in Indonesia called MountTambora. More than 13,000 feet high, Tambora blew up in 1815 and blasted 12 cubic miles of gase
• On August 26th 1883, a violent eruption began in Indonesia at Krakatoa, locally known as Krakatau. During the next 24 hours, hot avalanches of ash raced down the volcano and across the sea. Most of the volcanic island collapsed into the ocean, triggering tsunamis and creating a giant underwater crater, or caldera.
• jan 12 2020 - march 31 2022 mt. taal eruption
• volcanic process involves eruptive and non-eruptive activities in a volcano, which is composed of an extremely hot mantle under the crust. in some cases, an extremely hot mantle forms in the lower area, liquefying the upper mantle into superheated magma. magma originates 60-200 km below earths surface and can reach 1,400*C
• volcanic activities usually happens if the following occurs:

  1. confining pressure decreases as a result of decompression from the magma rising from a higher pressure point to a lower pressure point .
  2. vapor pressure increases because the magma cools, which initiates a crystallization process that enriches the magma content.
• • Seismic tomography maps the velocity disruptions in the Earth’s interior using mathematical modeling of P and S wave travel times. However, some irregularity of the source in time and space, as well as the insufficient coverage of recording stations, limit global seismic tomography.
• magma is made up of gases, water, and other flammable substances in additional to molten rock
• crystallization in magma happen as the molten rock cools and solidifies
• magma foam is a frothy bubbling mixture of gas and magma that is frequently observed during some volcanic eruptions
• when vapor pressure exceeds confining pressure magma rises towards the surface, allowing dissolved gas to expand and form vesicles. these vesicles make magma less dense than the surrounding rock, allowing it to move upward.
• before an eruption, magma cracks beneath the volcano, causing earthquakes, land surface deformation, and gas release. during an eruption, volcanic gases break magma into tephra, and if not fragmented, lava flows occurs if the molten rock is not fragment.
• felsic refers to rocks or magma that have more silica tetrahedrons which means, they have more oxygen. this composition gives felsic magma the highest gas content and viscosity
• the word felsic is a combination of feldspar and silica
• pyroclastic flows are the most dangerous features of volcano eruptions; hot gas, ash, and volcanic rock can flow down its slopes extremely fast and destructively.
• true or false

  true as pyroclastic melts snow and ice, it provides water through which the debris may flow causing lahar to run down the base of the volcano