A very big meteor that enters the earth's atmosphere can trigger an explosion similar to nuclear bombs.
Check out the tunguska event.
https://en.wikipedia.org/wiki/Tunguska_event>The Tunguska event (occasionally also called the Tunguska incident) was a 3–5 megaton[3] explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of 30 June 1908.[1][4] The explosion over the sparsely populated East Siberian taiga flattened an estimated 80 million trees over an area of 2,150 km2 (830 sq mi) of forest, and eyewitness accounts suggest up to three people may have died.[2][5][6][7][8] The explosion is generally attributed to a meteor air burst, the atmospheric explosion of a stony asteroid about 50–60 metres (160–200 feet) wide.[2][9]:p. 178 The asteroid approached from the east-south-east, probably with a relatively high speed of about 27 km/s (60,000 mph) (~Ma 80).[2] Though the incident is classified as an impact event, the object is thought to have exploded at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than hitting the Earth's surface, leaving no impact crater.[10] 