Nepal has been hit with a magnitude 7.3 earthquake, and aftershocks as strong as magnitude 6.3 are still being felt. It has been just over three weeks since the magnitude 7.8 earthquake hit the country, leaving more than 8,000 dead, scores injured and millions displaced.

Sadly, scientists had predicted that another earthquake was coming—and many more will come in the future in this seismically active region.

The Himalayan region had been overdue an earthquake, since the last one that hit Kathmandu 80 years ago. During the earthquake on April 25, however, not all of the pent-up seismic pressure was released. This left room for more earthquakes in the near future.

That near future, however, could have been days—or years—away. Predicting the precise location and timing of an earthquake is not possible. There are simply no signals from the movement of the Earth’s crust that can definitely point to when a quake is triggered.

And then one occurred today, about 18km below the surface and east of Kathmandu. It is not clear yet if this quake has indeed released all the remaining pent-up pressure.

The movement of the Indian plate, which collided with the Eurasian plate and gave birth to the Himalayas, makes the region a seismic hot zone. On average, the Indian plate moves about 18 millimeters towards the Eurasian plate and slips underneath it. This movement loads up some of its energy into earthquake faults, which extend on a line from east to west, and the process is much like loading energy in a spring. And every so often that energy is released in snap, resulting in an earthquake.