[originaltext] A methane explosion at a coal mine in north-west Turkey kille

A methane explosion at a coal mine in north-west Turkey killed 13 workers—not 17 as earlier repored— Turkish officials have said. They said 18 people were in hospital, with four in critical condition. The blast on Tuesday caused an underground chamber to collapse at a mine 20km(12 miles) outside Dursunbey, in Balikesir province, Some 33 workers were rescued after the explosion, which came two months after a blast at a mine in Bursa killed 19. The mine’s owner said it had buried the miners nearly 820ft(250m)below the surface. Labour Minister Omer Dincer said officials had initially overstated the death toll because four bodies had been counted twice.
    The safety record of Turkey’s coal mining industry lags behinds that of most industrial nations, analysts say. The country’s worst mining disaster was in 1993, when 270 miners were killed near the Black Sea port of Zon-guldak.
Questions 1 and 2 will be based on the following news item.
1. How many workers were killed in the methane explosion?
2. What is the main topic of the news item?