Both earthquakes occurred on a strike-slip fault similar to the San Andreas Fault system, according to the U.S. Geological Survey . The first tremor, a 7.2 magnitude event at 22:04 UTC, was immediately followed by a 7.5 magnitude mainshock at 22:05 UTC. The shallow depth amplified the shaking intensity across a heavily populated region . The USGS PAGER system assigned a 44% statistical probability that total fatalities could exceed 10,000 .
Both earthquakes occurred on a strike-slip fault similar to the San Andreas Fault system, according to the U.S. Geological Survey . The first tremor, a 7.2 magnitude event at 22:04 UTC, was immediately followed by a 7.5 magnitude mainshock at 22:05 UTC. The shallow depth amplified the shaking intensity across a heavily populated region . The USGS PAGER system assigned a 44% statistical probability that total fatalities could exceed 10,000 .