One of the most comprehensive studies ever of flood risk has determined that more than 17 million people in eight cities along the Atlantic and Gulf coasts are at the highest risk of being affected by flooding. Using machine learning, historic flood data and 16 factors representing hazards, exposure and vulnerability, the study published Wednesday in the journal Science Advances has come up with what is likely the most comprehensive model of coastal cities’ risk of flood damage. Researchers are alarmed by the findings, including that more than 4 million people are at risk in New York City, alone, and that 99% of people and buildings in New Orleans are vulnerable.

Japan has issued an advisory for northern coastal areas for an increased risk of a possible mega-quake following a 7.7-magnitude quake earlier Monday. The Cabinet Office and the Japan Meteorological Agency said there is 1% chance for a mega-quake occurring in the area over the next week or so. That's up from a 0.1% chance during normal times. The agency issued a tsunami alert following the quake, and a small tsunami was reported in some areas. One injury has been reported. Shinkansen bullet trains connecting Tokyo and Shin-Aomori have been partially suspended.