Seismology is the science that studies earthquakes: its helps us predict them (at least in which regions they're likely) and gives some information to engineers of what they need to take into account when building structures in the areas prone to earthquakes.
A positive externality or an external benefit that occurs if some of the benefits of the production or consumption of a product spillover into a third party that does not have to pay and even if you don't get vaccinated and others get it first.
While a negative externality or the diseconomy is one that imposes a negative impact and effects on the unrelated third party and due to it imposes the costs to the product and the services of polluting effects.
