A magnitude 7.2 foreshock and a magnitude 7.5 earthquake struck northern Venezuela yesterday; many aftershocks have followed. At least 164 persons were killed and close to 1000 were injured; unfortunately, these early counts are almost certain to rise.
A complex band of faults between the Caribbean Plate and the South American Plate runs across northern Venezuela. As the Atlantic Ocean continues to open, a process that began during the Jurassic Period, about 150 million years ago, the North and South America Plates have been moving westward. Eventually, the much smaller Caribbean Plate became wedged between them, setting the stage for earthquakes when pressure between the plates is released. These major events trigger pressure release in numerous side faults, producing aftershocks throughout the region.
The primary magnitude 7.5 quake was the second strongest ever recorded in Venezuela, weaker only than a magnitude 7.7 earthquake in 1900. Hopefully, it will retain that title for many years to come; then again, a more powerful quake could occur tomorrow as the geologic map of Planet Earth continues to evolve.
