Japan's Prime Minister Naoto Kan (l.) shouts 'Come on, Japan' along with Ishinomaki Mayor Hiroshi Kameyama (c.) and other people as he visits Ishinomaki, a port town devastated by the March 11 earthquake and tsunami in northeastern Japan, on April 10. Kyodo News/AP
Japanese workers remove rubble and garbage from a graveyard in Ishinomaki, Japan, on April 15. Sergey Ponomarev/AP
Japanese soldiers clear the rubble from a classroom at Okawa Elementary School, severely impacted by the March 11 earthquake and tsunami, in Ishinomaki, Japan, on April 11. Kyodo News/AP
A man walks through the debris at Okawa Elementary School in Ishinomaki, Japan, on April 5. Vincent Yu/AP
A Japanese soldier hurls a tire from a classroom at Okawa Elementary School in Ishinomaki, Japan, on April 11. Kyodo News/AP
A Japanese man removes mud and rubble from his home Ishinomaki, Japan, on April 15. Sergey Ponomarev/AP
A Japanese man removes wall blocks as he cleans the area around his home in Ishinomaki, Japan, on April 15. Sergey Ponomarev/AP
A Japanese worker gets on his earth mover in Ishinomaki, Japan, on April 15. Sergey Ponomarev/AP
Pacific earthquake: An 8.0 Pacific earthquake hit about 1,000 miles northeast of Australia. Over the past half-century, three 9.0 or higher 'superquakes' have hit the Pacific's Ring of Fire, pushing scientists to rethink their models of earthquake formation.
ByBecky Oskin, Our Amazing Planet
The 8.0 Pacific quake that hit the Solomon Islands tonight should be about most powerful earthquake possible, according to seismologists' theories of earthquake cycles. And the earthquakes that rocked Tohoku, Japan in 2011, Sumatra in 2004, and Chile in 1960 — all of magnitude 9.0 or greater — should not have happened. That might mean earthquake prediction needs an overhaul, some researchers say.