By Steve Herman

A powerful aftershock has rattled the quake-scarred region in Japan's Niigata Prefecture where more than 30 people have died and 100,000 have been homeless for four days. Meanwhile all of Japan watched rescuers pull a little boy alive from a vehicle buried since Saturday's initial tremor.

The powerful aftershock, the strongest in the past four days, registered 6.1 on the Richter Scale, and caused panic among many survivors.

Traumatized survivors in makeshift shelters threw themselves to the floor, screaming as they huddled together to wait out the latest of hundreds of aftershocks to hit the region since the initial jolt on Saturday.

At least five people were reported injured and some buildings were damaged, but casualties were minimized because few people in the hardest-hit communities were in their homes.

The morning-time tremor did prompt an emergency order for a thousand rail passengers to evacuate the train station in the town of Nagaoka, which officials said was in danger of collapse.

At a news conference later in the day, Masahiro Yamamoto, earthquake section chief of the Japan Meteorological Agency, pleaded with residents in the Niigata region who evacuated their homes on Saturday not to return yet.

Mr. Yamamoto says another quake of similar strength could be just hours or days away.

Amid the gloom, there was a bit of joy just hours after the huge aftershock.

In a dramatic scene broadcast live on all five national television networks, firemen worked amid the aftershocks to pull a two-year-old boy out of a crushed van. The vehicle, also carrying his mother and three-year-old sister, had been buried on a steep incline under large rocks after a quake-triggered landslide.

The boy, trapped for 90 hours and covered with mud, was hoisted in a rescue basket to a helicopter hovering above the pulverized rural highway. But firemen say neither the mother nor the daughter had a pulse by the time they were reached. Earlier in the day the rescue team had said its specialized equipment had detected three distinct heartbeats.

Officials are calling the boy's rescue the second miracle of this series of quakes. Transportation experts expressed astonishment that none of the 151 passengers aboard a bullet train were injured when the train derailed at high speed during the initial Saturday evening tremor.

Steve Herman, VOA News, Tokyo.注释：
aftershock 余震
rattle 使不安
Niigata 新滹（日本本州岛中北岸港市）
tremor 地震
Richter Scale 里克特震级
panic 恐慌
traumatize 使受伤害
makeshift 暂时的
shelter 避难所
huddle 蜷缩在一起
jolt 摇晃
casualty 人员伤亡
evacuate 疏散
Nagaoka 长冈（日本本州岛中北部城市）
Japan Meteorological Agency 日本气象厅
firemen 消防员
van 货车
landslide 崩塌的泥石
hoist 升起，吊起
miracle 奇迹
astonishment 惊讶
derail 出轨