2.3 Vulcanicity

• Meaning and causes of vulcanicity
• Intrusive features: batholith, laccolith, lopolith, phacolith, sill, dyke
• Extrusive features: types of volcanoes, craters, calderas, lava plateaus, hot springs, geysers
• World and Kenyan distribution of features due to vulcanicity
• Significance of vulcanicity to human activities
• Disaster preparedness and management

• investigate the causes of vulcanicity in the Earth
• describe features resulting from vulcanic activities in the world
• illustrate the global distribution of features due to vulcanicity
• examine the significance of vulcanicity on human activities
• acknowledge the effects of vulcanicity on the environment

“Why study vulcanicity?”

“Why do people continue to farm on the slopes of active volcanoes?”

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1. Vulcanicity: what happens and what it builds
   40 min · 2 practice tasks · quiz
   Why molten rock rises, and the landforms it makes above and below the surface.
2. Where volcanoes are, and what they mean for people
   40 min · 2 practice tasks · quiz
   The world and Kenyan distribution, the real benefits, the real dangers, and how communities prepare.
3. Causes of vulcanicity in the East African Rift
   40 min · 1 practice tasks · quiz
   Why magma rises where Kenya is splitting: thinning crust, faults, heat and pressure, with hot spots as the exception.
4. Magma, lava and viscosity
   40 min · 1 practice tasks · quiz
   One substance, two names, and why runny basaltic lava builds shields while sticky lava builds explosive Kenyan cones.
5. Intrusive features: batholith to dyke
   40 min · 1 practice tasks · quiz
   Naming batholith, laccolith, lopolith, phacolith, sill, dyke and plug, and how erosion turns them into Kenyan hills.
6. Shield, composite and cinder volcanoes in East Africa
   40 min · 1 practice tasks · quiz
   Three cone types matched to Longonot, the Chyulu Hills, Menengai's small cones and Nyamuragira.
7. Craters, calderas and lava plateaus
   40 min · 1 practice tasks · quiz
   Vent versus collapse versus flood: Menengai and Suswa as calderas, and the Yatta Plateau as a long phonolite flow.
8. Hot springs, geysers and fumaroles
   40 min · 1 practice tasks · quiz
   Groundwater on hot Rift rock: Bogoria geysers, Magadi springs, Olkaria fumaroles, and why a geyser is not a hot spring.
9. Kenya's Rift volcanoes from Turkana to Magadi
   40 min · 1 practice tasks · quiz
   A named north-south chain: The Barrier, Silali, Menengai, Olkaria, Longonot, Suswa, plus Mount Kenya and the Aberdares off-axis.
10. World distribution of volcanic features
    40 min · 1 practice tasks · quiz
    Ring of Fire, Mid-Atlantic Ridge, Mediterranean belt, East African Rift and hot spots - four kinds of plate setting.
11. Benefits of vulcanicity to Kenyan livelihoods
    40 min · 1 practice tasks · quiz
    Soils, Olkaria geothermal, tourism, Magadi soda, catchments and building stone - the case for living with volcanoes.
12. Volcanic hazards and negative effects
    40 min · 1 practice tasks · quiz
    Lava, ash, gas, lahars and the Goma warning: why valleys and downwind farms around Longonot are not equally at risk.
13. Volcanic disaster preparedness and management
    40 min · 1 practice tasks · quiz
    Before, during and after: monitoring, hazard maps, evacuation, and why Kenyan policy must live with people on fertile slopes.