Well, people say it for a very simple reason. That is, the earth has ALWAYS experienced earthquakes and big storms
Seismographic records do not go back that far into history, so we do not know about earthquakes that happened 1,000, even 500 years ago. But, we do know, from written record, that there have been many deadly earthquakes throughout history (among many other devastating events, such as disease and famine and war).
Physical events do not teach us reliable, spiritual truths. We cannot trust that the recent events are signs from God, for God does not tell us to look to the world for Truth.
He tells us to watch, and we do not watch in the world. We watch in God's word. God's word is where we find truth, not by seismology and guess work.
So, one must look towards God's word for answers, and when one does look into the Scriptures and studies them carefully, in prayer, they may see the truth that God has to reveal. In fact, in our day, since we are so close to the end, God has revealed a lot of information concerning the timing of the end.
God is now warning His people that the first day of the Day of Judgment will be on May 21 of this year. The Bible is assures us this is true.
But, it is not because the world has revealed it, but God has revealed it in His word.
http://the-latter-rain.com/timing-of-events-introduction.html
http://ebiblefellowship.com