The following verses in Hebrews 12:26-27 where the Lord shakes the earth, causing all the things that are made to be shaken out, is in reference to the great tribulation in which many who now profess themselves as Christians will fall away. This is when family members who fall away, then turn in other family members who do not fall away, unto their deaths (Mark 13:12).
Hebrews 12:25 See that ye refuse not him that speaketh. For if they escaped not who refused him that spake on earth, much more shall not we escape, if we turn away from him that speaketh from heaven: 26 Whose voice then shook the earth: but now he hath promised, saying, Yet once more I shake not the earth only, but also heaven. 27 And this word, Yet once more, signifieth the removing of those things that are shaken, as of things that are made, that those things which cannot be shaken may remain.
Mark 13:12 Now the brother shall betray the brother to death, and the father the son; and children shall rise up against their parents, and shall cause them to be put to death.