Natural Disasters Week 4

Haiti Earthquake

  • Lasted 35 seconds

  • Between 100,000 and 220,000 people died

  • 250,000 to 300,000 buildings collapsed

  • 10,000 people died from Cholera

Neither the USGS nor any other scientists have ever predicted a major earthquake

Volcano

  • A volcano is a vent for molten rock

  • 169 active volcanoes in the US

  • Volcanoes are at divergent and convergent boundaries and hot spots

  • Wherever molten rock can reach the surface is a volcano

  • Hot mantle rock or magma melts overlying continental rocks

  • Flux melting: add volatiles (water, carbon dioxide) to mantle rock (melts easier)

  • Lava = magma that reaches the surface

  • Mafic Magma - very hot, low silica, low viscosity

  • Cinder cone - conical piles of tephra

  • Built of ejected lapilli, pea-sized fragments, piled up at a vent

PROFESSOR’S FAVORITE STAR WARS CHARACTER IS R2-D2

Source of Magma

  • Tame is partial melting of the mantle and oceanic crust

  • Mantle source - ultramafic and mafic magmas

  • Crustal source - intermediate, and felsic magmas

  • Rhyolitic magma typically forms when continental crust melts, producing felsic, high‑silica magma

Volcano Types

  • Large cone shaped

  • Composed of alternating layers of basaltic, andesitic, and rhyolitic tephra

  • Often symmetric with steep sides

  • Pyroclastic debris: explosive eruptions

  • Lahars: ash moved by water (consistency of wet cement)

PROFFESROS FAVORTIE COLOR IS BLUE