Friday's earthquake lasted around 10 seconds longer than the Fourth of July earthquake in Searles Valley. According to the US Geological Survey, it was followed by at least 16 aftershocks of magnitude 4 or greater. The agency has warned of a 50% chance of another magnitude 6 quake in the coming days, and a 10% chance of a magnitude-7 tremor in the next week.
Update (1145ET): Less than 12 hours after seismologist Lucy Jones warned of another large quake, a massive 7.1 quake just hit 17km NNE of Ridgecrest.
This continues the swarm of aftershocks that has hit all day... (Seismologists at Cal Tech said Friday afternoon that there had been around 1,400 aftershocks since Thursday's 6.4-magnitude quake, with 17 of those with a magnitude of 4 or above.)