What this lesson teaches
I can explain how tectonic hazards in the region could affect Singapore and how much preparation is proportionate.
Syllabus K329, Topic 5.2, Key Question 2. How might tectonic hazards affect Singapore?
Make a guess
Singapore has no active volcano and lies far from plate boundaries. Is it completely safe from tectonic hazards?
- No, because Singapore has active volcanoes.
- Yes, because tsunamis cannot reach islands.
- No. Distant hazards can still reach it.
- Yes, because hazards stay at plate boundaries.
Show the answer
No. Distant hazards can still reach it.
Distance removes direct hazards like lava. But large earthquakes off Sumatra can be felt here, and ash from Pinatubo affected Singapore's air in 1991.
Singapore is far from active plate boundaries, but big regional earthquakes, tsunamis and volcanic ash can still affect it.
Singapore lies away from active plate boundaries and has no active volcano. So it avoids direct hazards like lava or ground rupture. But large earthquakes on the Sunda Megathrust off Sumatra can send waves far enough to be felt here.
Ground conditions matter. Soft ground can make shaking stronger. Loose, waterlogged ground can liquefy in strong shaking. So some reclaimed land needs careful checks by qualified engineers. Reclaimed land will not necessarily liquefy, and a felt tremor does not always cause damage.
A big undersea earthquake can cause a tsunami. MSS says Singapore is fairly sheltered by the land and shallow seas around it, but monitoring still matters.
Put these in order
The 2004 Indian Ocean tsunami did little harm in Singapore. Put the chain in order.
- Tsunami waves race across the Indian Ocean.
- Singapore is shielded, while coasts across the Indian Ocean suffer great loss of life.
- A huge amount of seawater is pushed out of place.
- Sumatra and the Malay Peninsula stand between the waves and Singapore.
- The Sunda Megathrust off Sumatra ruptures in a huge earthquake.
Show the answer
- The Sunda Megathrust off Sumatra ruptures in a huge earthquake. The rupture moves a large area of seabed, so the water above it is suddenly pushed out of place.
- A huge amount of seawater is pushed out of place. The displaced water spreads out as a series of long waves.
- Tsunami waves race across the Indian Ocean. The waves spread outward from the source, so coasts open to the Indian Ocean lie in their path.
- Sumatra and the Malay Peninsula stand between the waves and Singapore. Land in the way blocks the waves, so little of their energy reaches Singapore.
- Singapore is shielded, while coasts across the Indian Ocean suffer great loss of life.
Volcanic ash can travel far. MSS records that ash from Mount Pinatubo's June 1991 eruption affected Singapore's air quality, although its flights were not affected. Ash can also disrupt regional airports and trade.
- Sunda Megathrust
- Fault off Sumatra; big quakes can be felt here.
- Reclaimed land
- May need checks for soft or loose ground.
- Pinatubo, 1991
- Its ash affected Singapore's air quality.
Step by step
An event happens nearby
A fault ruptures or a volcano erupts.
Effects travel
Seismic waves, tsunamis and ash take different routes.
Local conditions matter
Distance, shelter, wind and ground shape the impact.
Real examples to use
Indian Ocean tsunami, 2004
An earthquake on the Sunda Megathrust off Sumatra caused a tsunami that killed over 200,000 people around the Indian Ocean. Singapore was shielded by Sumatra and the Malay Peninsula.
Worked example: Felt does not mean damaged
Two sites can feel the same earthquake differently because of their ground and buildings. Feeling shaking shows the waves arrived. Judging damage needs evidence about the ground and buildings.
Watch out for this
Every megathrust earthquake will cause a destructive tsunami in Singapore.
Singapore is fairly sheltered. A possible hazard is not certain destruction.
Check your understanding
Why might flights be disrupted even though Singapore has no erupting volcano?
- Lava flows can reach Singapore across the sea from Sumatra.
- Ash can drift through regional airspace and close routes.
- Tremors from distant eruptions shake Changi's runways.
Show the answer
Ash can drift through regional airspace and close routes.
Yes. Ash travels with the wind.
Check your understanding
Why was Singapore largely spared by the 2004 Indian Ocean tsunami?
- The tsunami began far away, near the coast of East Africa.
- Sumatra and the Malay Peninsula shielded it from the waves.
- Singapore has a tsunami wall around the island.
Show the answer
Sumatra and the Malay Peninsula shielded it from the waves.
Location and land masses reduced its exposure.