Final answer:
The chain of volcanoes located in a region with no visible plate boundaries is formed over a hotspot, with the Hawaiian Islands being a prime example. This hotspot has created a long chain of volcanic islands and maintains several active volcanoes, including Mauna Kea.
Step-by-step explanation:
The major chain of volcanoes in a region where no plate boundaries are evident is located over a geologic feature known as a hotspot. Specifically, the Hawaiian Islands are an example of such a volcanic chain. These islands are formed by a stationary hotspot beneath the moving Pacific Plate, where heat rises from the Earth's interior, creating volcanoes on the ocean floor that build upwards to form islands.
The Hawaiian hotspot has been active for at least 100 million years, generating a chain of volcanic islands that stretches over 3,500 kilometers. The heat from this hotspot maintains three active volcanoes, two on land and one under the ocean. Notably, Mauna Kea, which is now dormant, is one of these Hawaiian volcanoes and is considered one of the world's premier locations for astronomy thanks to its substantial height and diameter.