PHS-1010 Melinda Huff: Plate Boundaries & Hotspot Comparisons

Transform Boundary (Mechanism)

Shear stress; plates slide horizontally past one another without creation or destruction of lithosphere.

Transform Boundary (Landforms & Features)

Fault traces, strike-slip faults, and offset stream channels. No trench or mid-ocean ridge.

Transform Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (frequent, shallow). Volcanoes: NONE.

Transform Boundary (Global Example)

San Andreas Fault (California).

Oceanic Divergent Boundary (Mechanism)

Tensional stress; plates pull apart on the seafloor, generating new oceanic crust.

Oceanic Divergent Boundary (Landforms & Features)

Mid-ocean ridge system and central rift valley.

Oceanic Divergent Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (shallow). Volcanoes: Fissure eruptions with basaltic lava (no tall volcanic cones).

Oceanic Divergent Boundary (Global Example)

Mid-Atlantic Ridge.

Continental Divergent Boundary (Mechanism)

Tensional stress; continental crust is pulled apart, thinned, and stretched.

Continental Divergent Boundary (Landforms & Features)

Continental rift valleys and long linear seas/lakes.

Continental Divergent Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (shallow). Volcanoes: Basaltic volcanic activity / fissure eruptions.

Continental Divergent Boundary (Global Example)

East African Rift System & Red Sea.

Ocean-Ocean Convergent Boundary (Mechanism)

Compressional stress; older/denser oceanic plate subducts beneath younger oceanic plate.

Ocean-Ocean Convergent Boundary (Landforms & Features)

Deep ocean trench + Volcanic Island Arc.

Ocean-Ocean Convergent Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (shallow to deep). Volcanoes: Highly explosive Composite Volcanoes (stratovolcanoes).

Ocean-Ocean Convergent Boundary (Global Example)

Japan Island Arc, Aleutian Islands, Mariana Trench.

Ocean-Continent Convergent Boundary (Mechanism)

Compressional stress; dense oceanic plate subducts beneath buoyant continental plate.

Ocean-Continent Convergent Boundary (Landforms & Features)

Deep ocean trench + Continental Volcanic Arc.

Ocean-Continent Convergent Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (shallow to deep). Volcanoes: Highly explosive Composite Volcanoes.

Ocean-Continent Convergent Boundary (Global Example)

Andes Mountains (South America) & Cascade Range (Mt. St. Helens).

Continent-Continent Convergent Boundary (Mechanism)

Compressional stress; two low-density, buoyant continental plates collide without subduction.

Continent-Continent Convergent Boundary (Landforms & Features)

Towering folded mountain ranges and severe crustal shortening/thickening.

Continent-Continent Convergent Boundary (Earthquakes & Volcanoes)

Earthquakes: YES (shallow to deep). Volcanoes: NONE (no subduction means no magma generation).

Continent-Continent Convergent Boundary (Global Example)

Himalayan Mountains.

Oceanic Hotspot (Mechanism)

Intraplate mantle plume rising from the deep mantle beneath moving oceanic crust.

Oceanic Hotspot (Landforms & Features)

Linear chain of volcanic islands with age progression away from the hotspot.

Oceanic Hotspot (Earthquakes & Volcanoes)

Earthquakes: YES. Volcanoes: Shield Volcanoes (broad, fluid basaltic lava flows).

Oceanic Hotspot (Global Example)

Hawaiian Islands (Mauna Loa & Kilauea).

Continental Hotspot (Mechanism)

Intraplate mantle plume beneath moving thick continental crust.

Continental Hotspot (Landforms & Features)

Massive calderas, bimodal volcanism, and secondary thermal features (geysers, fumaroles, hot springs).

Continental Hotspot (Earthquakes & Volcanoes)

Earthquakes: YES. Volcanoes: Calderas with explosive felsic/rhyolitic and basaltic eruptions.

Continental Hotspot (Global Example)

Yellowstone Caldera.

Plate Boundaries Matrix: Earthquake Occurrence

ALL 8 boundary and hotspot types experience earthquakes (YES across the entire chart).

Plate Boundaries Matrix: Settings with NO Volcanism

Transform Boundary and Continent-Continent Convergent Boundary (neither has subduction or mantle plumes).

Plate Boundaries Matrix: Settings with Composite Volcanoes

Ocean-Ocean Convergent and Ocean-Continent Convergent boundaries (both involve subduction).

Plate Boundaries Matrix: Setting with Shield Volcanoes

Oceanic Hotspots (e.g., Hawaiian Islands).

Plate Boundaries Matrix: Setting with Massive Caldera & Geysers

Continental Hotspots (e.g., Yellowstone).

Plate Boundaries Matrix: Setting with Folded Mountains & No Volcanoes

Continent-Continent Convergent boundary (e.g., Himalayas).