FACTBOX: Major recent events in U.S. coal mine safety

(Reuters) - The trapping of six coal miners at a Utah mine 1,500 feet underground after a collapse is a reminder that the industry is dangerous despite safety improvements since the second half of the 1900s.

Last year, the Sago explosion in West Virginia killed 12 miners and prompted Congress to pass new mine safety laws.

From 1997 to 2006 an average of nearly 33 coal miners have died annually in accidents. So far this year 10 miners have died, while 48 died in 2006, the most in a decade.

Coal mining is safer than it was during the first half of the last century when coal fueled America's great industrial growth, and it was common for accidents to kill more than 100 miners. Much less coal is burned for steel-making now, but it fires half of the country's electrical power generation.

Below is a list of major recent events in U.S. coal mine safety:

2007

--July. Coal mining company Massey Energy said new federal mine safety rules, inspired by the Sago disaster, could cost the company $24 million adding 50 to 75 cents per ton to the cost of its coal.

--Aug 6-7. Six miners were trapped underground at the Crandall Canyon Mine in Utah after a collapse of such force geologists are investigating whether it accounted for an earthquake registered at the same time. Private company Murray Energy owns the mine operator.

2006

--January 2. 12 miners killed at International Coal Group's Sago mine in West Virginia after an underground explosion. Another accident in the state within three weeks of Sago killed two other miners.

--Summer. Prompted by Sago, Congress passed the Miner Act of 2006 and President George Bush signed it into law. It was the first major revision to U.S. mine safety laws since 1977. It requires mines to:

-Provide more emergency supplies of breathable air along escape routes

-Develop and update a written emergency response plan

-Make available two experienced rescue teams capable of a one-hour response time

-Provide wireless two-way communications and electronic tracking systems for miners within three years

-It also gave the government the authority to shut down mines in cases where the operator has refused to pay a final safety fines and raised the criminal penalty cap to $250,000 for first offenses and $500,000 for second offenses