Toward the end of 2015, some in our Beyond family experienced earthquakes where they worked. It's a striking reminder: while we think of the chief danger to missionaries as being persecutors, really natural disasters, health, and corruption are far bigger issues. (Consider the air pollution in Beijing and pray for the workers who labor there, under severe adverse health risks.) We have personal experience with this. We arrived in Southeast Asia in early December 2005 - and just a few weeks later, we were digging friends out after the 9.3-magnitude earthquake and the Tsunami.
Given this, it's a good idea for missionaries to ask: is it possible a really bad earthquake will strike where you live? There are hundreds of thousands of earthquakes every year. The vast majority are barely noticed. Minor quakes are occurring all the time: while I was writing this article, ten earthquakes were measured, most measuring about 2.4 on the Richter scale. There is a relationship between the strength of the earthquake (magnitude, on the Richter scale) and the frequency it occurs: earthquakes of magnitude 5, for example, are about ten times less common than those of magnitude 4. Still, while magnitude-5 and stronger quakes are less frequent, they are still fairly common: in 2015, there were 1,554 of them. Of these, 145 were 6.0 or stronger, and 20 were over 7.0. (Just one was an 8.3, thankfully off the coast of Chile.) This is fairly close to the average over history: the USGS estimates there are typically 18 major quakes (7.0-7.9) and one major quake (8.0+) every year.
So the likelihood of a strong earthquake hitting somewhere in the world is seemingly almost certain--but the likelihood of a strong earthquake hitting one particular spot is far less. It's more certain in some places, and less in others, because of the way the fault lines work. It's easiest to see this on a map, and this one, from the Economist, shows all the earthquakes from 1995 to 2015 that were magnitude 7.0 or greater.
The greatest probability of any given earthquake (regardless of the size) is along the Pacific Seismic Belt, and along plate boundaries (mountain chains, such as the Himalayas). If you live "in the red dots," you're almost certainly going to see earthquake action. You must be aware and have a plan in place. If you're in much of Europe, Africa or the middle-to-east portion of the Americas, less concern is warranted.
Many earthquakes do not hit in populated areas (many, for example, are deep underground, or far off the coast). If a magnitude 6 earthquake (of which there are a hundred or more per year) strikes a populated area, it is almost certain to do some damage, and there will likely be a dozen or so deaths from falling buildings. A magnitude 7 earthquake can be considerably more destructive. The April 25th earthquake in Nepal, which measured 7.8, resulted in over 8,900 dead. (On the other hand there were several other magnitude-7 quakes in 2015, and most resulted in no deaths at all.) Magnitude 8 and 9 earthquakes will be disastrous if they strike a populated zone, no matter how much preparation is made. They can result in tens of thousands or even hundreds of thousands of deaths, and billions of dollars in property damage. A magnitude-8 quake will cause years of disruption and recovery. For all that we know about earthquakes, no one can predict when or where an earthquake will strike next. We can really only note the probabilities. Seismologists look in history to see the frequency of earthquakes in a given area, and the time between each one; they measure tectonic activity; they make an estimate of when "another" is more likely. More than 100,000 people died in Turkey due to earthquakes in the 1900s; this report suggests Istanbul is due for a magnitude-7 earthquake within the next 30 years (62% probability). This report suggests Tehran is "overdue" for an earthquake; one strikes about every 150 years, and a magnitude-7 earthquake could very well see millions killed. If you are in an earthquake-prone area, the possibility of multiple quakes of magnitude 5.0 or greater within the year are very high--almost certain. The possibility of a powerfully destructive magnitude 8 or 9 quake is far lower--if there is only one per year, it's less likely it will be in your precise location. A magnitude 7 earthquake is a better than even chance, and while not as destructive as the strongest quakes, it be devastating on its own, with significant property damage, lives lost, people injured, and logistics and politics disrupted. Any agency deploying personnel to a place where a magnitude-5 or -6 earthquake happened in the past year ought to invest in contingency planning and disaster preparations. Further, every agency ought to be prepared for the possibility of a magnitude-8 earthquake striking. One form of preparation is for the possibility of personnel in the midst of severe disruption, or worse injured or killed. Yet the odds of this happening to any single individual is fairly low, so I don't personally worry about it all that much. Another form of preparation is for how an agency will participate in help and reconstruction after such a disaster. Let me say this as carefully as I can: while I don't ascribe to the idea that disasters are always sent by God as some form of punishment, I do believe God will use us in the open doors after disasters to bring blessing to places that were previously closed to the Gospel--and we should be ready to do that. If a large scale earthquake happens every year, it's a recurring "door opening" that we should be prepared to step through. Justin's forecast, for people within earthquake zones (on map):multiple magnitude-5 quakes?: YES, >95% ... (low damage, no or <10 deaths) ... REACHED more than one magnitude-6 quake?: YES, >75% ... (low damage, <20 deaths, some injured) ... REACHED at least one magnitude-7 quake: YES, >60%, NO 40% ... (significant damage, 100-1,000 deaths, injuries) ... REACHED: Mag-7 Quakes in N America and Southwest Indonesia (Sumatra) at least one magnitude-8 quake: NO, >75% ... (for any single individual. But for world as a whole, YES, 75%) ... catastrophic: thousands of deaths, hundreds of thousands injuried at least one magnitude-9 quake: NO, >90% ... (for any single individual. But for world as a whole, NO, 55%) ... catastrophic: hundreds of thousands dead/injured, billions of dollars in damage
As with all forecasts, note the significant possibility of the inverse happening (I'm 45% certain of a mag-9 quake); if it should, the most likely "outlier" will be very destructive.
Update 1/25: Mag-5 Quakes in N America, Central Asia, E Asia, SE Asia, N Africa, Pacific Mag-6 Quakes in N America, N Africa, Pacific, L America, E Asia, SE Asia, S Asia Mag-7 Quake in N America, in SW Indonesia