Volcanism and Magma Properties

• Volcanism occurs when magma finds a path through the lithosphere.
• Tectonic forces can squeeze a magma chamber, creating pressure and pushing the magma upward.
• Magma rises because molten rocks are less dense than the surrounding solid rocks.
• Volcanoes are hills, mountains, or fissures with an opening or rupture where molten rocks, hot gases, and ashes are ejected.
• Craters are formed by the removal of pre-existing materials.

Magma

• Underground molten rocks that influence the formation and eruption of volcanoes.
• Magma chambers are where magma is stored.

Magma Properties

• Viscosity is the resistance of a fluid to flow.
• Granitic magma has high resistance, high viscosity, and a high silica content of 70%.
• Andesitic magma has medium resistance, medium viscosity, and a medium silica content of 60%.
• Basaltic magma has the least resistance, least viscosity, and a least silica content of 50%.

Volcano Activity

• Active volcanoes have erupted within the last 10,000 years.
• Inactive volcanoes have no record of eruption but may erupt with little to no warning.
• 80% of volcanoes form at convergent boundaries, 15% at divergent boundaries, and 5% at hotspots.

Types of Volcanoes

Cinder Cone Volcanoes

• Built from volcanic fragments (pyroclasts).
• Small, less than 300m high.
• Formed near/inside large volcanoes, often in groups

Composite Volcanoes

• Andesitic lava flows out of a vent over a long period.
• Form a perfect, symmetric cone like the Mayon Volcano.

Shield Volcanoes

• Composed of basaltic lava.
• Slightly dome shaped.
• Have a wide base.

Types of Eruptions

• Phreatic eruptions are driven by steam when ground water vaporizes.
• Vulcanian eruptions involve large quantities of accumulated gas, resulting in a cauliflower cloud.
• Strombolian eruptions involve basaltic or andesitic lava and produce less ash.
• Pelean eruptions involve viscous lava forming a dome.
• Phreatomagmatic eruptions involve the ejection of volcanic gases that form a radially spinning ring cloud.
• Plinian eruptions are the most destructive, forming a tall column of ash that causes ash fall.

Parts of Volcanoes

• Vent: Central opening.
• Caldera: A large depression formed when the summit of the volcano collapses.
• Fumaroles: Secondary vents that only emit gases.
• Magma Chamber: Large pool of magma beneath the Earth.
• Conduit: Passage in a volcano through which magma travels up.
• Crater: Circular depression connected to the vent.

Volcanic Hazards

• Pyroclastic Flow: Fast movement of ash and rocks mixed with hot gases.
• Ash flow: Shower of ash that causes respiratory problems, following the wind's direction.
• Volcanic Gases: Hot mixture of water vapor.
• Lava Flow: Steam-like flow of incandescent molten rocks.
• Lahar: Thick mixture of volcanic ash and water generated along river channels, which can bury areas with debris.

Benefits of Volcanoes

• Geothermal energy is heat contained in fluids and rocks thousands of feet below the surface.
• It is used as an energy source, derived from hot water stored underground through drilling wells.
• Lava makes the soil richer for agriculture.
• Volcanoes provide elements/compounds like minerals such as gold, copper, and silver.

Weather

• Short-term changes in the atmospheric condition.

Climate

• The long-term general prevailing condition of an area.
• PAGASA is the Philippine Atmospheric Geophysical Astronomical Services Administration.

Elements of Weather

• Atmospheric Temperature: How cold or hot the air is, measured by a thermometer.
• Atmospheric Pressure: Force per unit exerted by air due to its weight, measured by a barometer.
• Affected by insolation: the solar radiation that reaches the earth that depends on the length of daytime and nighttime
• Wind: Natural movement of air caused by variations in air pressure. Direction describes where the air originated.
• Coriolis Effect: Causes the wind to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere

Precipitation

• Energy from the sun causes water on Earth to evaporate and rise into the atmosphere
• Includes condensed water vapor like rain, drizzle, hail, snow, and sleet.
• Goes through water cycle
• Relative Humidity: Indicates the amount of water vapor in the atmosphere.

Factors that Affect Climate

• Latitude: Distance of a location north or south of the equator.
• The poles experience the greatest difference in day lengths during summer.
• Altitude: Vertical elevation or distance of an area above sea level. As altitude increases, temperature decreases.
• Distance from the Sea: Coastal areas have lower temperature ranges. Inland areas are cooler.
• Topography: Arrangement of the surface features of a place or region.
• Mountains alter wind patterns.
• A rain shadow occurs when rain only pours on one side of a mountain, creating a desert on the other side.

Climates of the World

• Tropical: Warm all year.
• Dry: Low precipitation, no rain.
• Temperate: Mid annual temperature.
• Continental: Hot summer, cold winters.
• Polar: Cold all year.

Global Wind Patterns

• Worldwide pattern of wind and weather.
• Prevailing winds blow in a given direction over a region.
• Global Warming: An increase in the average global temperature driven by human and natural impacts.
• Increase in carbon dioxide.
• Rise in sea level and climate change.
• Climate Change: Changes in the normal weather and climatic patterns observed around the globe.

Constellations

• Groups of stars that form patterns in the sky.
• International Astronomical Union (IAU): Divided the sky into 88 constellations with borders/regions.
• Asterism: Patterns formed by stars but not recognized by the IAU.

The Milky Way Galaxy

• The galaxy the solar system belongs to.
• Composed of billions of stars bound together by gravity.
• Celestial Sphere: Imaginary sphere of infinite radius with Earth at the center.
• Ecliptic: The sun traces a path on the central sphere.
• Local Sky: The sky you see from where you stand.
• Zenith: Point directly above you.
• Meridian: Certain border/region in the sky.
• Horizon: Boundary where Earth's surface meets the sky.
• Zodiac Constellations: Include Capricorn, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius.
• Astronomy: Scientific study.
• Astrology: Beliefs that attempt to explain human affairs and predict future events.

Explore the properties of magma, factors influencing its movement, and characteristics of volcanic eruptions. Understand the relationship between tectonic forces and volcanic activity. Learn about volcanic hazards, geological features, and the benefits of volcanoes.