Are 2 magnitude 3.5 earthquakes the same as 1 magnitude 7.0 earthquake in terms of the energy released?
No, the earthquake scale is logarithmic meaning the curve goes sharply upward. So the energy of a magnitude 3.5 earthquake is not half of a magnitude 7.0, more like a quarter. That is why large earthquakes are so destructive and you barely feel small earthquakes.
A magnitude 6.4 earthquake strikes southern Taiwan Part 5