"For example, a Type I civilization is a truly planetary one, which has mastered most forms of planetary energy. Their energy output may be on the order of thousands to millions of times our current planetary output. Mark Twain once said, ”Everyone complains about the weather, but no one does anything about it.“ This may change with a Type I civilization, which has enough energy to modify the weather. They also have enough energy to alter the course of earthquakes, volcanoes, and build cities on their oceans."
Stopping plate tectonics also has longterm consequences for the deep carbon cycle and climate which we'd better be prepared to handle. Though we probably have to tackle that particular problem way before.
I did not ay cool earth's core, not did Michio Kaku. Given the amount of people living near fault lines, certainly we should be able to manage e.g. magma flows/ pressures in an ideal, long term future.
From http://mkaku.org/home/articles/the-physics-of-extraterrestri... :
"For example, a Type I civilization is a truly planetary one, which has mastered most forms of planetary energy. Their energy output may be on the order of thousands to millions of times our current planetary output. Mark Twain once said, ”Everyone complains about the weather, but no one does anything about it.“ This may change with a Type I civilization, which has enough energy to modify the weather. They also have enough energy to alter the course of earthquakes, volcanoes, and build cities on their oceans."