How are the alignments and age distribution patterns of the emperor seamounts and Hawaiian islands explained

Plate tectonics and seafloor spreading are main causes for the distribution pattern and age of seamounts.

Explanation:

The Hawaiian islands and the emperor are undersea mountain chains that reach above sea level in Hawaii. It is composed of the Hawaiian Ridge and extends from the southeast to the northeast under the north pacific ocean.  The chain consists of 80 volcanoes the oldest emperor seamounts are about 81 million years old. These have been created by the hotspots of volcanic activity. They have shifted with the movement of the pacific plate some 47 million years ago. However, the chain is made by the movement of the oceanic crust. Along with the upwelling of the hot rocks form below. Thus the movement of the crust away from the source of magma eruptions becomes less frequent. Gradually as the volcano sinks and erodes it becomes a small island atoll.