The first quake to rock the Vanuatu archipelago was a humongous 7.8 magnitude. Fifteen minutes later, a 7.7 followed by a massive aftershock of 7.3.
"In some sense this is an odd looking earthquake sequence because of the very high number of earthquakes of similar size," says USGS geophysicist Ross Stein.
Stein says the map doesn't show the thousands of smaller aftershocks less than a magnitude 5.0. The event generated a small tsunami, but warnings were quickly canceled.
"Most earthquakes, even of this size, do not produce large tsunamis. We're acutely aware of the ones that do, but often they don't," says Stein.
And news of the quakes shook nerves at the Crossroad Calvary Chapel, a Samoan church in San Jose.
It's been a little over a week since friends and relatives were lost in an earthquake-fueled tsunami that killed 178 Samoans. That tsunami was followed by devastating quake in Indonesia.
"I think this is a warning. Not only to the Samoan islands but around the world," says Havelock Pomele, a Samoan church member.
Despite the concentrated series of quakes all within the so-called Ring of Fire, scientists at the USGS are reluctant to draw any conclusions.
"We are experiencing something unusual. And whether or not it's unusual because these earthquakes are interacting, or because we just happen to have snake eyes on the roll of the dice, isn't clear to us and we'll try to figure that out," says Stein.
PROGRAMMING NOTE: The ABC7 special "15 Seconds: The Earthquake of 1989" airs on October 17, 2009 at 10 p.m.