Still reeling from a 6.8-level earthquake, Japan's northwestern Niigata prefecture was hit by another strong trembler Sunday afternoon measuring 4.9 on the Richter scale, the strongest in a series of aftershocks to hit the region since the first big quake Saturday, meteorological authorities reported. Japan's Jiji Press reported 19 people dead as a result of the earthquakes, among them a 2-month-old infant and several children. More than 1,500 people have received medical treatment, and many are still missing. The new quake was centered on the city of Ojiya, worst affected by Sunday's seismic activity. There have been no warnings of tidal waves, or tsunami, so far. The initial quake, measuring 6.8 on the Richter scale, shook the region on Saturday at 6 p.m. (0900 GMT) and has since triggered hundreds of aftershocks. Authorities have warned of yet more aftershocks to follow. Some 70,000 people evacuated, many of them spending the night in the cold around open fires or oil-fired heaters and under blankets to keep warm. Emergency services arrived with drinking water and food on Sunday. Helicopters ferried more people from the worst-affected areas to safety on Sunday, and search dogs looked for the missing. Houses were partially destroyed and streets ripped open. Landslides struck after the quakes in some regions which had been ravaged by typhoon Tokage just three days previously. Eighty people died in the typhoon. Many people were injured by falling glass and other objects. NHK showed footage of fallen electricity masts and traffic lights, torn up roads, wrecked shops and homes. --more 1301 Local Time 1001 GMT