>>4087667 (lb)
the Richter scale is not very good at predicting the likely effects of an earthquake. The japanese shindo system is much better at that.
the richter scale is based on energy released, while the shindo system uses lots of variables such as depth, geology and wavelength to determine the actual damage on the surface. thats why a richter 7 can cause no damage, while a richter 4 can wipe out towns. Knowing the energy released is pointless of and by itself.