Final answer:
Onna experienced more severe earthquake damage because of constructive interference of seismic waves and local factors like building materials. Buildings like gymnasiums and churches often fail more due to their structural features, and resonance can also play a role in the extent of the damage.
Step-by-step explanation:
The town of Onna experienced more severe damage during the L'Aquila earthquake than other nearby towns due to a phenomenon known as constructive interference of seismic waves. Constructive interference can lead to higher amplitude waves at certain locations, which increases the intensity of shaking and damage. Additionally, buildings such as gymnasiums and churches often fail more during earthquakes because they usually have larger open spaces and structural configurations that may not be as resistant to shaking, compared to smaller, more compartmentalized family homes. Moreover, local factors such as building materials, hydrostatic pressure changes in the water table, and design adaptations to historical threats can affect a building's resilience to earthquakes.
Another factor to consider is resonance, which occurs when the natural frequency of a building matches the frequency of the earthquake waves. This can cause one building to collapse while neighboring buildings remain intact, as the building height reaches the condition necessary to set up a standing wave. Reflections of seismic waves off denser rocks underground can also exacerbate this effect, as observed in areas like Onna.