Dalal Street witnessed selling pressure after the government on Thursday issued fresh alerts on tsunami.In a board-based sell-off, the barometer BSE Sensex lost 45.40 points or 0.69 per cent to settle at 6,522.54. It took a U-turn around mid-morning after it had climbed about 35 points. The S&P CNX Nifty shed 9.80 points or 0.47 per cent to 2,059.80.The market surged in the last one month or so on the back of strong inflow from FIIs. From a low of 5,961.71 on November 19, 2004, the Sensex has risen nearly 600 points.