Earthquakes

BAM, IRAN DECEMBER 2003

• 6.6 Richter scale
• 25,000 deaths
• economic loss of $10 billion
• 90% of buildings made of mud
• emergancy vechiles damaged by earthquake
• average income of $3,900
• isolated
• 18,000 buildings destroyed

HAWAII USA OCTOBER 2006

• 6.7 Richter scale earthquake
• 0 deaths
• $73 million in damage
• average income of $30,000
• minor damage in hawaii

Oceanic crust is 6-11 km is 200 million years old, made up of Basalt which consists of silica, magnesium and average density of the oceanic crust is 3g/cm3

Continental crust 30 to 40km which is over 1.5 billion years old mainly consists of igneous rocks granite rocks and average density of the continental crust is 2.7g/cm3

Topography- steep gradient and influence of gravity causes landslides

SLAB PULL - gravity is pulling down the oceanic crust because its densier, pulls down. The slab causes others to spilt and oceanic crust becomes exposed to convection currents. this happens at a destructive boundary

RIDGE PUSH- happens at constructive boundary when plates move apart. Magma rising from convection cell cols and forms new land. The convection currents are the driving force - forcing plates apart

CONSTRUCTIVE PLATE BOUNDARY

ridge push means the motlen magma is moving away from an area of high pressure to low pressure. This results in the oceanic crust being pulled apart. This leds to the youngest geology closet to spreading compared to oldest geology further apart. Along…