Chapter_2_Living_with_Tectonic_Hazards_-_Risk_or_Opportunity_

GATEWAY 1: Why are some areas prone to tectonic hazards? What is a natural hazard? ● A natural azard ​ is a naturally occurring event that threatens human lives and causes damage to property. ● Tectonic hazards ​ are caused by plate movements when continental crusts and ocean floors move. ○ They can include earthquakes or volcano eruptions. ● Climate hazards ​ are caused by severe and extreme weather and climate conditions. ○ They can include floods or storms. Internal structure of the earth Crust Lithosphere = Crust + Uppermost Mantle Oceanic Continental Location ● Beneath deep oceans ● Beneath Earth’s continental land masses and under shallow seas close to continent Thickness ● Between 5 - 8 km ● Between 35 - 70 km Density ● Heavy, dense. ● Lighter rock. Minerals ● Mainly basalt. ● Granite Age of Rock ● Less than 200 million years old. ● Wide range from very recent to 4 billion years old. Mantle Upper Mantle Lower Mantle ● 800C to 3000C ● 2900km thick ● Mostly solid rock that flows under high temperature and pressure. ● Layer of solid rock + asthenosphere ● Solid rock Core Outer core Inner Core ● Central part of Earth ● 3500km thick ● 3000C to 5000C ● Mainly liquid ● 2100 km thick ● Solid ● 1400 km thick What are tectonic plates? ● Tectonic plates are solid slabs of rocks which are made up of the continental crust or oceanic crust or both, attached on its underside to the upper part of the mantle. ● Edges of these plates are called plate boundaries. ● Important plates are, ​ NA Plate, SA Plate, Pacific Plate, African Plate, Eurasian Plate, Indo-Australian Plate, Antarctic plate How and why do plates move? ***FAQ*** ● Tremendous heat found in Earth’s core causes rocks in mantle to melt and become magma. ● Liquid mantle material, called magma, is intensely heated and expands, rising up. ● Rising and spreading lava pulls the plates apart, causing them to diverge as they are dragged along and move away from each other. ● Then the magma cools and sinks, pulling the plates along. ● The sinking mantle material heats up again as it nears the core, creating a convection current and causing the whole process to repeat. Notes by some weirdo called Conrad Soon.. I don’t guarantee the full accuracy of the information here. Special thanks to Mrs Wong, the most wholesome and pure Geography ahma.

Different types of plate boundaries Divergent plate boundaries ● Oceanic-oceanic plate divergence ○ Associated landforms are ​ mid-ocean ridges ​ and volcanic islands. ■ Mid-Atlantic Ridge ​ where the ​ North American and Eurasian plates diverge. ■ Iceland ​ and the ​ Azores ​ examples of volcanic islands formed. ○ As the two oceanic plates move apart, they form fractures at the plate boundary. ○ The magma wells up from the zone of divergence, cools and solidifies to