I am saying tradgeties happend before and nobody never even knew about, Today I can google and I can find out about the latest tragedy.
Do your really think Hashem was warning jews to do tshuva about some earthquake somewhere in the middle of Pacific that nobody even knew about? Some of these earthquakes we only know about them.
In 1908 a comet or some other extra terrestrial object hit in the middle of Sibera (Its called the Tunguska event) the exact details were not exactly known at the time and more information was not discovered until the 1920’s, when some exploration was able to be done in the area and much more is not known. How many Gedolim wrote about this event at the time it happend and told us to do tshuva for it.