Final answer:
Aftershocks of historic earthquakes like the 1811-12 New Madrid events are related to ongoing plate tectonics, involving movement and interaction of the Earth's tectonic plates over time.
Step-by-step explanation:
The aftershocks of the 1811-12 New Madrid, Missouri, earthquakes are indeed still occurring today, and this phenomenon relates to plate tectonics. The Earth's crust is divided into a number of large and small tectonic plates that float on the semi-fluid asthenosphere beneath. These plates move and interact at their boundaries, which leads to various geologic phenomena. Earthquakes occur as the plates grind against each other, while volcanic eruptions can happen when one plate moves under another - a process known as subduction. The energy from these interactions can continue to release as aftershocks over extended periods of time after the initial quake. Moreover, the Ring of Fire, a zone prone to earthquakes and volcanic activity, is an example of the results of such plate interactions.