According to the U.S. Geological Survey, the first earthquake struck at 10:33 a.m. July 4 with a 6.4 magnitude and is now considered a foreshock. A second quake shook the area the following day at 8:20 p.m. with a stronger 7.1 magnitude. Estimated economic losses of what the USGS now calls the Searles Quake are at least $1 billion; furthermore, the air control tower at Plant 42 was also damaged. The exact extent of that damage is still under review.