List of largest non-nuclear blasts

Wow, I stumbled upon this really interesting wiki page Here are a few of them:

2005 Hertfordshire Oil Storage Terminal fire. On 11 December 2005 there were a series of major explosions at the 60 million gallon (273 million litre) capacity Buncefield oil depot near Hemel Hempstead, Hertfordshire, England. The explosions were heard over 100 miles away, as far as the Netherlands and France, and the resulting flames were visible for many miles around the depot. A smoke cloud covered Hemel Hempstead and other nearby towns in southern Hertfordshire and Buckinghamshire. There were no fatalities, but there were around 43 injuries (two serious). The RAF Fauld Explosion. On November 27, 1944 3,670 tons of bombs exploded in a Royal Air Force underground storage facility, killing 78 (officially) and leaving a crater 400 feet deep by three-quarters of a mile wide. Halifax Explosion. On December 6, 1917 two ships collided in the harbour of Halifax, Nova Scotia, one carrying about 2,600 tons of various explosives, mostly picric acid. After the collision the ship caught on fire, drifted into town and eventually exploded. More than 1,900 people were killed and much of downtown Halifax was destroyed. An evaluation of the explosion's force puts it at 2.9 kt. Delft Explosion. About 40 tons of gunpowder exploded on October 12, 1654, destroying much of the city of Delft in the Netherlands. Over a hundred people were killed and thousands wounded.

Battle of Messines, June 7, 1917 Over a period beginning more than a year before the attack, the attackers had tunnelled under the German trenches and planted almost 455 tonnes (1,000,000 lb) of ammonal there. A heavy bombardment of the German positions was initiated and then halted. The defenders returned to their positions expecting an assault to follow. The detonation of the explosives all timed for 3:10am, killed approximately 10,000 German soldiers. It said to have been heard as far away as London and Dublin, and was possibly the loudest man-made noise made up to that date. In Switzerland the explosions registered as an earthquake. The real attack then followed. Not all of the explosives went off. Two of the original 21 mines failed to ignite [1] due to one reason or another. On July 17, 1955, a lightning strike set off one of the remaining mines, the only casualty being a dead cow. The 21st mine is believed to have been found in recent years, but no attempt has been made to remove it. Several large water-filled craters still mark the original positions of the German trenches. "Gentlemen, we may not make history tomorrow, but we shall certainly change the geography." Remark by General Plumer to his staff the evening before the attack