Prepare for a shock!Prepare for a shock!

Aim: To discover what causes earthquakes Aim: To discover what causes earthquakes and how they are measured.and how they are measured.

Resources

p.108-109 Geog.1

Richer Scale Outline

How do they happen?How do they happen?Two plates try to Two plates try to SLIDESLIDE past one past one another. Over another. Over hundreds of years the hundreds of years the friction builds up and friction builds up and then then BANGBANG, the , the pressure is released pressure is released and the plates and the plates JOLTJOLT past one another. This past one another. This causes an earthquake. causes an earthquake.

Epicentre – The place Epicentre – The place directly above the directly above the focus where the quake focus where the quake is feltis felt

Focus is the point Focus is the point underground where underground where the plates slipthe plates slip

See b/works slide 6 for animation

Alaska, 1964Alaska, 1964

How are they measured?How are they measured?Magnitude

Richter Number

Relative Intensity

LowLess than

2.0Barely felt, minimal or no damage.

Moderate

2.0 to 4.4Noticeable, damage to buildings, sidewalks, weak structures.

Strong 4.5 to 7.0 Heavy shaking, falling walls and bridges.

Very strong

Greater than 7.0

Massive shaking, ground moving, landslides, great damage to structures. Liquefaction

****Seismographs measure the strength of the quake********Seismographs measure the strength of the quake****

The three types of earthquakeThe three types of earthquake- - Extension WorkExtension Work - -

Using page 3 of your booklet, explain with Using page 3 of your booklet, explain with illustrations the three different types of illustrations the three different types of earthquake.earthquake.

HomeworkHomework: Find out if we have ever had an : Find out if we have ever had an earthquake in France. When was the last one earthquake in France. When was the last one and where was the epicentre? Use Google and where was the epicentre? Use Google images or visit the library. Marked /10 Simages or visit the library. Marked /10 S