Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Ex Input:
Question: Body waves travel through the earth and arrive at seismograms before what? Answer: surface waves

Ex Output:
Body waves travel through the Earth and arrive at seismograms before surface waves.

Ex Input:
Question: What is the strength of an earthquake called? Answer: magnitude

Ex Output:
Earthquake: What Does Magnitude Mean? at http://www. livescience. com/20538-earthquake-magnitude-video. html (2:00).

Ex Input:
Question: Sand dunes migrate when sand is blown up a slope and this force pulls it down the other side? Answer: gravity

Ex Output:
Sand is blown up a slope. Gravity pulls it down the other side. This is how dunes migrate.