A string of recent earthquakes has left some areas in shambles and led some to question whether other areas at risk are doing enough to prepare for potential devastation.

The most destructive of these recent quakes occurred on April 16 in Ecuador, a 7.8 magnitude event that has (so far) killed more than 230 people, destroyed infrastructure, and left many trapped in the wake of landslides and collapsed structures. Across the Pacific, Japan was hit with a 7.0 magnitude quake on the same day. It left 32 dead and capped off a week of unsteady ground; the country had also suffered several smaller quakes on Aprol 14 and 15.

The Richter Scale, used to measure the energy released by earthquakes, is based on a logarithmic scale. This means that an earthquake that registers 7.0 on the scale is actually 10 times stronger than one that measures 6.0. When earthquakes reach the upper register of this scale, incredible destruction results. However, while the differences between the forces of earthquakes certainly matters, the effect of any given quake has more to do with local infrastructure, environmental factors, and population density.

The worst recorded earthquake in the past 100 years happened in Chile on May 22, 1960. An earthquake with a magnitude of 9.5 left 1,655 dead, 3,000 injured, 2 million homeless, and $550 million in damage, according to the U.S. Geological Survey. However, in 1964, the Great Alaska Earthquake, which registered a 9.2 magnitude, killed 131, and caused around $311 million in damage.

More recently, Nepal suffered a 7.8 magnitude quake on April 25, 2015, that took more than 8,000 lives, and crippled areas of the country. The U.N. has estimated that more than 8 million people were affected by the quake. 

The continental U.S. has not faced one of these devastating earthquakes in some time. That isn’t to say that earthquakes don’t occur. In the first four months of 2015, Oklahoma registered 260 earthquake events above 3.0 magnitude. And for those on the West Coast, mainly California, smaller events are a regular part of life. Yet these quakes rarely cause significant damage.

But a much, much larger earthquake is likely to hit the U.S., especially in the Pacific Northwest, in the future. The Cascadia zone, which includes the Juan de Fuca subduction zone, runs from Vancouver Island to northern California, has caused the largest earthquake in the mainland U.S. history (around 8.9-9.2 magnitude in 1700). Many seismologists are worried that an event of similar scale could occur in the coming decades, given that Juan de Fuca seems to cause earthquakes on an average of one every 230 years.

The resulting quake and tsunami would be the worst natural disaster in the history of the U.S.

Based on the scenario that the Cascadia fault is ruptured by a 9.0 quake, FEMA has projected that more than 10,000 people would die, 30,000 would be injured, and the economic damage would top $70 billion. The odds of such an event occurring are hard to predict with total accuracy, but when “reduced to simple odds” the chances of a 9.0 earthquake in the next 50 years are around 1 in 10. A smaller earthquake, though less devastating, is also far more likely.

And regardless of the exact timing, FEMA’s experts say, an earthquake along the Cascadia zone is inevitable because of the nature of plate tectonics.

With all the challenges that face our nation today, something like a future natural disaster is hard to get attention for. Yet if we’re to adequately prepare for “the big one,” it’s vital that we provide the necessary time and resources in order to mitigate the damage of this eventual earthquake. Because it’s not a question of if it will come, but when.