&gt;It turned out that all of those eruptions, from the Pacific, Atlantic and Arctic Oceans, took place from January to June. 
The cause, she proposed, is Earth’s slightly elliptical orbit around the sun. That changes the strength of the sun’s gravitational pull on Earth during the year and, as a result, the magnitude of the tides that squeeze the planet.<p>I felt fairly informed amount about underwater geology, but the idea that the crust down there is so delicate that solar tides can cause eruptions was new to me.