For the purposes of this question, let's ignore the causality issues of time travel itself.
Suppose our hero, or an accomplice of our hero, has invented a time travelling apparatus. It works like this: a person steps into a chamber, sets some controls, and initiates a jump through time. The apparatus then transports itself and anything inside it to the designated time. It is powered by a set of handwavium-unobtainium-based power cells that provide enough power to sustain a small number of time jumps between recharge cycles.
To keep this from becoming a too-easy deus ex machina, I want this apparatus to be able to transport through time but to be forced to consistently appear in the same location on Earth at the target time. That is, if you start at Brandenburger Tor, Berlin, Germany on midnight, New Year, and go half a year plus twelve hours into the past, you end up at Brandenburger Tor, Berlin, Germany at noon in the height of summer. In other words, it somehow works in such a way that we can (and indeed are forced to) disregard the Earth's own rotation, the Earth's orbital movement around the Sun, the Sun's orbital movement in the Milky Way, and so on, but we cannot instruct it to move geographically to another location as part of the time jump.
There is no need for the apparatus to function at all further away from the surface of the Earth than some small distance, say 1 km or so (to allow for high-rise buildings).
How could I possibly explain the fact that the apparatus after transporting through time appears in the same geographical location, as explained above?
The explanation absolutely does not have to meet strict scientific criteria (we're throwing those out already with time travel in the first place), but it'd be nice if it doesn't break suspension of disbelief too badly.
The time jumps will be on the order of hundreds of years or less, so geological stability should not be a major concern and might even provide an interesting obstruction to our hero. (Thanks Pavel Janicek for mentioning this issue.)