Final answer:
The two main factors that determine the size or magnitude of an earthquake are the energy released and the geological conditions.
Step-by-step explanation:
The two main factors that determine the size or magnitude of an earthquake are the energy released and the geological conditions. The energy released during an earthquake is a measure of its power and is quantified using various scales, such as the Richter scale or moment magnitude scale. Geological conditions, such as the type of fault or rock composition, can affect how an earthquake propagates and the amount of damage it causes.