A massive wildfire in northeastern Japan has expanded, putting more homes at risk. Some 2,000 firefighters from across the country have been deployed to O-funato city in Iwate Prefecture to battle the blaze that has been raging for more than five days. Andrea Heng and Hairianto Diman examine the possible triggers of the fire in that area with Samuel L. Manzello, Visiting Professor, Institute of Fluid Science, Tohoku University