(CNN) -- Gerard Fryer, senior geophysicist at the Pacific Tsunami Warning Center put the magnitude of the quake into perspective -- and allayed much of the concern. "A 7.7 is a big, hefty earthquake. It's not something you can ignore," he said. But, he added, "this earthquake was partly under the island and mostly under shallow water." He went on to say: "I think we have to be thankful it happened where it did . .. if that were a heavily populated area, it would have caused significant damage. It definitely would have done significant damage if it had been under a city."