1)convection currents in the earth’s core cause the tectonic plates to move - false 2)a magnitude...
TRANSCRIPT
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:
Thursday, April 20, 2023
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
Thursday, April 20, 2023
Types of Waves
3 different waves move through rock like ripples in a pond.
Video clip: seismic waves
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.
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.
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.
Types of Waves
All three together.
Now do the worksheet on P, S, L waves
Features P- Waves S - Waves L - Waves
Full Name Primary Secondary Long
Action Push / pull Up / down / sideways
Rolling
Travelling Speed
Speed 5 - 13 km/s
Speed 3 - 8 km/s
Speed 3 - 4 km/s
Arrival First Second Third
Damage Level Minor Moderate Major
In Water Pass through Absorbed Pass through
Location In crust In crust Surface only
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
released
wavesfocus
epicentre seismographslocation
Locating the Epicentre
It takes data from at least 3 seismographs to locate the epicentre.
Here is the data from 3 stations.Seismic Station Distance (km)
Auckland 4000
Hawaii 4000
Fiji 3000
An earthquake occurred approximately 4000 km from Auckland, 4000 km from Hawaii and 3000 km from Fiji. Find the epicentre.
0 km 4000 km
2000 km
Epicentre