Plate Tectonics Topic 2 Quiz

What causes the sudden release of seismic waves during an earthquake?

• Rocks slipping to a new position

• Rising magma

• Friction between rock masses

• Stress on the edge of the plate

Answer explanation

Only when the stress on the edge of the plate exceeds the strength of the fault, the rock fractures and slip to a new position, which causes seismic waves to be released.

What affects the magnitude of earthquakes?

• The number of seismic waves

• Amount of energy released through ground movement

• The size of the fault movement, also known as how much the rocks on either side of the fault moved from its original position

• The amount of dissolved gases

Answer explanation

The larger the fault movements, the bigger the earthquakes.

Which scale measures larger earthquakes more reliably?

• Richter Scale

• Moment Magnitude Scale

• Volcanic Explosivity Index

• Seismograph

Answer explanation

Seismograph is not a scale, but an instrument used to record the motion of the ground during an earthquake. Moment Magnitude Scale is more reliable as it calculates earthquakes' magnitude based on total energy released.

What causes magma to force its way upward and break through weak areas in the Earth's crust?

• Dissolved gases in the magma

• Tectonic forces

• Friction between rock masses

• Seismic waves

Which type of magma results in violent and explosive eruptions.

Answer explanation

Dissolved gases in viscous magma cannot escape easily as they are 'trapped', hence pressure may build up until gas explosions blast rock fragments and lava into the air.

Which type of magma is usually more viscous?

• High silica magma

• Low silica magma

Where is the largest concentration of earthquakes found?

• Eurasian Plate

• Pacific Ring of Fire

• Mid-Atlantic Ridge

• San Andreas Fault

Give an example of a hotspot volcano (a volcano found away from plate boundaries).

Answer explanation

Mauna Loa volcano in Hawaii, USA

Which hazards are generally localized, in other words, near the earthquake or volcano?

• Tsunami and Volcanic Ash

• Soil Liquefaction and Lava flow

• Ground Shaking and Tephra

• Landslides and Pyroclastic Flows

Give an example of a earthquake hazard that spread beyond its geographical location.

Answer explanation

2004 Indian Ocean tsunami travelled almost 5000km to Africa