There has been a massive earthquake in Chile, magnitude 8.8. It has resulted in a tsunami warning from the Pacific Tsunami Warning Center for the entire Pacific ocean basin. As I write, it is 1910 UTC on the 27th, past initial arrival time for many locations. But not past first arrival for many. The predicted arrival times are also available (keep an eye on the site for updated information!). Tsunami can be dangerous for hours after first arrival time as different waves arrive. Tsunami does not necessarily equate to disaster, some of the wave heights being observed are less than 1 meter (3 feet). But if you're near the Pacific Ocean, it is definitely time to get informed and take appropriate action.
h/t Phil Plait
See All of My Faults Are Stress-Related: How big was that EQ? Magnitude vs intensity in Chile and Haiti Kim Hannula's blog, shearsensibility, for informed discussion of what magnitude means. 8.8 is far bigger a quake than the 7.0 that hit Haiti.
4 hours ago