Mine safety in coal mines, which in turn can initiate more extensive coal dust explosions. For this reason, rock dusts such as limestone dust are spread throughout coal mines to diminish the chances of coal dust explosions as well as to limit the extent of potential explosions, in a process known as rock dusting. Coal dust explosions can also begin independently of methane gas explosions. Frictional heat and sparks generated by mining equipment can ignite both methane gas and coal dust. For this reason, water is often used to cool rock-cutting sites. Miners utilize equipment strong enough to break through extremely hard
Merrimack Valley gas explosions fires were reported over a very short period of time in the towns of Lawrence, Andover, and North Andover beginning about 4:15pm (EDT). Through the evening emergency crews responded to between 40 and 80 fires. At one time, as many as 18 fires were burning at once, and Andover officials struck a maximum 10-alarm response. Andover's fire chief described "billows of smoke coming from Lawrence behind me, I could see plumes of smoke in front of me within the town of Andover, it just looked like an absolute war zone." A Lawrence resident described finding his boiler on fire after