Update 2: PTWC has cancelled the regional warning. A tsunami was in fact generated, but the waves have been measured and are very small (about 1.5 inches in height).
Updated: The Pacific Tsunami Warning Center states that a tsunami was generated by this earthquake. The size of the tsunami is not yet known, and the warning has not been extended to other areas of the Pacific. (Remember,tsunamis can be very small.)
An earthquake tentatively measured by the USGS at magnitude 7.9 has struck Tonga in the South Pacific. It's unknown at this time if the quake has generated a tsunami, but given the size and depth of the quake, the Pacific Tsunami Warning Center has issued a regional tsunami warning for the areas around the quake's epicenter.
Tsunami warning is one of those things that's like "volcano monitoring" - it's something that's done by a small number of scientists who work in relative obscurity. The budget line for our tsunami monitoring program contains quite a few things that people who are skeptical of the federal government's spending habits might question - like providing geophysicists with Hawaiian homes.
In actuality, this is one of those cases where appearances are deceiving. Tsunami warnings are, at least in theory, capable of preventing all fatalities from tsunamis. The waves take time to travel, and only areas that are relatively near the coastlines are typically impacted. Given even a limited amount of time, it's possible to get everyone at risk out of the way.
That's good, because there is often only a limited amount of time.
The earthquake that generated the current tsunami occurred at 18:17 UTC today. That's early in the morning near the epicenter, and it's also fairly early (8:17 am) in Ewa Beach, Hawaii, where the warning center is located. The tsunami (whatever height it turns out to have been) struck parts of Tonga by about 18:45, and Pago Pago at about 19:25.
The first tsunami warning statement was issued at 18:30 UTC - less than 15 minutes after the earthquake occurred.
The federal government provides housing for geophysicists because that's what it takes to be able to provide tsunami warning services without having to hire excessive numbers of scientists. The scientist on duty can be at home - he's not chained to the consoles - but thanks to the marvel of modern computers and communications he can get to the computers and start assessing an earthquake within a couple of minutes.
Sometimes, government spending that looks stupid is stupid, but frequently it's not.