Take into account that the kinetic energy is given by the following formula:
where,
m: mass of the asteroid = 700*10^6 kg = 7*10^8 kg
v: speed of the asteroid = 19000 m/s
Replace the previous values of the parameters into the formula for K and simplify:
Hence, approximately 2.5*10^17 J of energy would be released when the asteroid impacts the Earth