validation (2011 tohoku)

Question 1

· explain the cause/s of the hazard

Answer 1

• The 2011 Tohoku earthquake struck offshore of Japan, along a subduction zone where two of Earth’s tectonic plates converged.
• Oceanic plates are denser than continental plates, which means they have a higher subduction potential. They are constantly being pulled into the mantle, where they are melted and recycled into new magma.
• In a subduction zone, the Pacific plate subducted beneath the overriding Eurasian plate, building up energy that is released as earthquakes.
• Radioactive radiation from the core (heat source) causes the convection current, in this case, the mantle current carrying the ocean plate is forced downward.
• The Tohoku earthquake was a complete releasing of the centuries of built-up stress between the two tectonic plates.
• Scientists drilled into the subduction zone soon after the earthquake and discovered a thin, slippery clay layer lining the fault. The researchers think that this clay layer allowed the two plates to slide 50 meters, facilitating the enormous earthquake and tsunami.
• The earthquake, offset, and displaced a large area of the ocean floor. The sudden vertical displacements, disturb the ocean’s surface, displace water, and generated destructive tsunami waves which travelled across the Pacific Ocean, resulting mass destruction and floods towards the mainland.