It is widely held by the scientific community that Milankovitch cycles are instrumental to the timing of glaciations. As such, the Milankovitch cycles are also instrumental in determining the timing of Terracycles.
There were mass burials of Woolly Mammoths about 43,000, 23,000, and 11,000 years ago. This corresponds roughly to a cycle every 11,000 years. Every 11,000 years the earth tilt swings between being closest to the sun during January or closest to the sun in July. When the sun is closest to the sun during these months it is summer in either the Northern or Southern Hemisphere and thus the effects of summer and winter are magnified. The strong swing between cold winters and hot summers wreaks havoc on the earth's climate systems.
Image courtesy of the Solar Data Analysis Center at the NASA Goddard Space Flight Center
It appears the ocean has an electromagnetic property that reacts to solar activity. When an intense burst of solar radiation hits the Earth's magnetosphere, it squeezes the ionosphere, which then presses down on the ocean, which then press down on the tectonic plates. This process is more intense during solar max of the solar cycle. Since nearly the entire Pacific and Nazca Plates are covered by the Pacific Ocean, these particular plates are affected the most during solar storms. There may be a pattern of magnitude 5 and greater earthquakes in the South Pacific Islands region within days after a major solar eruption arriving at Earth.
When a solar storm erupts, it can send a Coronal Mass Ejection (CME) toward the earth. A CME is a powerful burst of protons with a strong electrical charge. The CME slams into the earths magnetosphere causing the earth's magnetic field to contract and expand. This contraction induces electrical currents in the ionosphere in the form of auroras, on the surface of the planet (sometimes resulting in wide spread power outages), and in the core and mantle of the earth.
There appears to be a mechanism for solar X-rays (or other solar high energy radiation) to heat the earth directly much like a potato is heated in a microwave oven. Evidence for internal heating of the earth due to high energy solar radiation appears when comparing solar X-ray flux to volcanic activity at Mt Hood, Oregon, and Mt Rainier, Washington.
The softer the magma becomes, the easier it is for the crust above to slip over it. Also, the heated magma can more easily find its way to the surface where it erupts in the form of volcanoes.
As the mantle becomes softer and the crust moves more easily, the crust gains momentum. The tectonic plates begin moving faster during the solar maximum and slow down during the solar minimum. In the period of time when solar X-ray activity decreases, the mantle coagulates somewhat. But with the momentum of the tectonic plates the coagulating mantle produces resistance to movement and there is a period of magnitude 7+ earthquakes. During the time of solar maximum, when the mantle is its softest, there are far more earthquakes than during solar minimum and nearly all of the earthquakes are magnitude 6 or lower. There are a few magnitude 7+ earthquakes during periods of high solar X-ray flux, but their causes are due to specific geological conditions.