GEOL 11: PRINCIPLES OF GEOLOGY 2nd Year
1st Sem
LESSON 8: Volcanism S.Y 2023 - 2024
● Pillow lava
Volcanism & Extrusive Processes
-What comes out of volcanoes
● Eruptive products
○ Lava
○ Pyroclast
○ Volcanic gasses
-Volcanic morphology
● Shield volcanoes
● Stratovolcano
● Monogenetic cones Tephra
● Dome -Umbrella term for the pyroclastic (rock and glass
● Caldera fragments) material explosively erupted by a
-Volcanic Eruption volcano
● Effusive vs Explosivity eruption
○ Volcanic Explosivity Index (VEI) Pyroclast
○ Dense Rock Equivalent (DRE) -Individual pyroclastic (rock/glass) fragment
● Types of Eruption
○ Magmatic
○ Phreatic
○ Phreatomagmatic
WHAT COMES OUT OF A VOLCANO
Lava
-Molten rock effusively erupted by a volcano ● Block/Bomb
-Molten rock material on the earth’s surface ● Lapilli
-Can come out as lava flows ● Ash
-Generally more degassed than its magma ● Pyroclastic fragments
counterpart
-Types of Lava
Volcanic Gasses
● Pahoehoe lava
○ Rope-like surface features
● A’a lava
● Sulfur
1st Sem
LESSON 8: Volcanism S.Y 2023 - 2024
● Pillow lava
Volcanism & Extrusive Processes
-What comes out of volcanoes
● Eruptive products
○ Lava
○ Pyroclast
○ Volcanic gasses
-Volcanic morphology
● Shield volcanoes
● Stratovolcano
● Monogenetic cones Tephra
● Dome -Umbrella term for the pyroclastic (rock and glass
● Caldera fragments) material explosively erupted by a
-Volcanic Eruption volcano
● Effusive vs Explosivity eruption
○ Volcanic Explosivity Index (VEI) Pyroclast
○ Dense Rock Equivalent (DRE) -Individual pyroclastic (rock/glass) fragment
● Types of Eruption
○ Magmatic
○ Phreatic
○ Phreatomagmatic
WHAT COMES OUT OF A VOLCANO
Lava
-Molten rock effusively erupted by a volcano ● Block/Bomb
-Molten rock material on the earth’s surface ● Lapilli
-Can come out as lava flows ● Ash
-Generally more degassed than its magma ● Pyroclastic fragments
counterpart
-Types of Lava
Volcanic Gasses
● Pahoehoe lava
○ Rope-like surface features
● A’a lava
● Sulfur
