1. 1)Convection currents in the Earth’s core cause the tectonic plates to move - FALSE 2)A magnitude 6 earthquake is twice the size of a magnitude 3 earthquake - FALSE 3)S waves travel faster than P waves - FALSE 4)Shield volcanoes have viscous magma and steep sides - FALSE Do now: Just write TRUE or FALSE to the following: Wenerei, 11 Whiringa-ā-rangi 2015

2. Today’s Learning 1)Describe how earthquakes travel through the earth’s crust 2)Describe the characteristics of P, S and L seismic waves 3)Locate the epicentre of an earthquake Wenerei, 11 Whiringa-ā-rangi 2015

3. Types of Waves  3 different waves move through rock like ripples in a pond.  Video clip: seismic waves

4. Types of Waves  P-Waves or primary waves are the first waves to hit as they move the fastest (8km/s). They squeeze and stretch the rock.

5. Types of Waves  The next waves to hit are the secondary waves (S-Waves). These waves move at 5km/s and make the ground shake up and down as well as from side to side.

6. Types of Waves  Traveling at 4km/s are the last waves to hit, the L-Waves. These waves do the most damage as they travel near the surface of the crust.

7. Types of Waves  All three together.  Now do the worksheet on P, S, L waves

8. FeaturesP- WavesS - WavesL - Waves Full NamePrimarySecondaryLong ActionPush / pullUp / down / sideways Rolling Travelling SpeedSpeed 5 - 13 km/s Speed 3 - 8 km/s Speed 3 - 4 km/s ArrivalFirstSecondThird Damage LevelMinorModerateMajor In WaterPass throughAbsorbedPass through LocationIn crust Surface only

9. The energy ________ travels outwards as _____. The point in the Earth’s crust where this happens is called the _____, the point directly above the focus on the Earth’s surface is called the _________. Seismologists use ___________ to determine the magnitude and ________ of earthquakes. seismographs focus location waves epicentre released releasedwaves focus epicentreseismographs location

15. Locating the Epicentre  It takes data from at least 3 seismographs to locate the epicentre.  Here is the data from 3 stations. Seismic StationDistance (km) Auckland4000 Hawaii4000 Fiji3000

16. An earthquake occurred approximately 4000 km from Auckland, 4000 km from Hawaii and 3000 km from Fiji. Find the epicentre. 0 km4000 km 2000 km Epicentre