For my final project in a GIS-related course, I have chosen to look at the historical data of earthquakes in California to try and make a kind of risk assessment based on cities and their population density. For this, I have created a buffer around each earthquake, where the radius is dependent on the magnitude. The resulting circles are then areas of effect. These two layers look like the following:
What I would like to do is then, for each city polygon, count how many times a buffer intercepts with it, to get a number telling how many times, an earthquake has affected the area. I have been looking a bit into the "num_geometries" function of the field calculator, but am unaware whether this would be an ideal route to go.