A house destroyed by an earthquake.
The question of predicting earthquakes and knowing if the Big One is coming is still a mystery. In recent years, various forecasting models have been advanced, including the ability to measure thermal patterns of heat on earth, from space, to serve as a predictor. Scientists have found loopholes in this latest theory and, to everyone’s dismay, no single method is reliable for determining when an earthquake will strike. What remains fairly constant is that most large earthquakes occur along fault lines, where constant pressure from underlying tectonic plates can cause the ground to suddenly jerk, shake, and roll. Therefore, scientists can say that larger earthquakes are much more likely along fault lines, especially some known faults like the San Andreas fault, which runs through much of California.
So far, scientists have not found a reliable indicator of large earthquakes.
Therefore, the question of whether small earthquakes are precursors to large earthquakes is complex. First, you would have to define small earthquakes; Are these the ones people don’t usually feel or are they small 2.0-3.0 quakes that some people will feel? Still, if you come to a definition, you can’t say for sure that small earthquakes always precede big ones.
Most large earthquakes occur along fault lines, where there is constant pressure from underlying tectonic plates.
For example, in California, if you look at the US Geological Survey (USGS) website, you can count hundreds of earthquakes that are not even felt and occur with great regularity. If these small earthquakes are precursors to large earthquakes, then we would constantly have large earthquakes. On the other hand, small earthquakes suggest a certain level of fault activity and increased pressure, and scientists regularly suggest that we should all prepare for the Big Earthquake, as it could hit at any time. Therefore, it can be said that small earthquakes can presage large earthquakes because they suggest that eventually, at some point in the future, a large earthquake is likely to occur.
When a big earthquake occurs, the earthquakes of the previous days are called calamities. Small earthquakes that occur after a large earthquake are called aftershocks. Small earthquakes don’t necessarily have to be, but scientists can group seismic activity before and after a large earthquake in hopes of better understanding how and why earthquakes occur and under what circumstances they are most likely. Still, using the theory that small earthquakes are precursors to large earthquakes is not sound science. Only some of them are. It is more accurate to suggest that the active faults producing these tiny, unfelt tremors are likely to produce larger earthquakes.