Tremors- Hougang No. 9

Q1.What are tremors?

Q2. What causes it?

• Tremors are abrupt motion of the Earth's surface. They are caused by the sudden release in rocks of strain accumulated over time as a result of plate tectonics. As two plates move past each other they can become jammed. When sufficient strain has accumulated, the rock breaks, releasing a series of seismic waves as the plates spring free. Tectonic earthquakes will occur anywhere within the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. In the case of transform or convergent type plate boundaries, which form the largest fault surfaces on earth, they will move past each other smoothly and aseismically only if there are no irregularities or asperities along the boundary that increase the frictional resistance. Most boundaries do have such asperities and this leads to a form of stick-slip behavior. Once the boundary has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake.
  
• Q3. Will it affect Singapore?
• Tremors do not occur in Singapore as we are not at the epicenter. When an earthquake occurs in Indonesia, we can feel a slight tremor here in Singapore, but it does not cause any destruction or loss of lives.
• Q4. What it its effect?
• The force of earthquakes (magnitude) is measured on the Richter scale, and their effect (intensity) on the Mercalli scale. The point at which an earthquake originates is the focus or hypocentre; the point on the Earth's surface directly above this is the epicenter. When tremors occur at the ocean floor, it will cause a Tsunami.Earthquakes may result in disease, lack of basic necessities, loss of life, higher insurance premiums, general property damage, road and bridge damage, and collapse of buildings or destabilization of the base of buildings which may lead to collapse in future earthquakes. Earthquakes can also lead to volcanic eruptions, which cause further damages such as substantial crop damage. Tremors also create landslides!