Listen: There are quite a few lists out there ranking bombs, explosives, and the magnitude of their destructive or murderous power, but all deal with a specific category of explosive, like non-nuclear ordinance, or specific contexts, for example, domestic acts of terror in the US. Because of this, nearly every article out there (save the present one) either has the Russian "Tsar Bomb," or the Oklahoma City Bombing at the top of the list... conspicuously leaving out any reference to bombs deployed in combat and whose devastation is measured in casualties on the order of hundreds of thousands dead.
This is a list of the most destructive and the deadliest single-bomb detonations, and not just those that happened on US soil. Because death is at least slightly more tragic than property damage, we start with nuclear test detonations whose destruction is measured in megatons and in terms of blast radius. Further down the list are the deadliest explosions of a single "bomb," usually in the context of ideologically motivated terrorism. In-between are the nuclear tests and controlled explosions that turned deadly (another fact the blogosphere has thus far ignored). These are 15 of the most devastating, in any and every sense of the word, single bombs that have ever been detonated.
15 The Grapple Falls Far From the Tree
The "ton" in megaton (or megatonne) stands for one ton of TNT, the highly volatile chemical that gives dynamite its explosive personality and a ton of which generates about 4.2 gigajoules of energy. For the majority of us who do not need to know what a joule of energy is, 4.2 gigajoules would generate enough force to lift 42 kg. (20 lbs.) of mass about 4.2 million meters off the ground. The largest nuke in the so-called Grapple series of Brit-manufactured warheads yielded 3 megatonnes of face obliterating power and was detonated in the South Pacific (the island nation of Kiribati specifically) in the late 50s.
14 Operation Hardtack 1: Poplar
Operation Hardtack I was a series of thirty-five thermonuclear tests that took place across the Pacific theater (of war) and in the air, on the ground, and underwater; if anything, this massive military operation was a show of power and a way to demonstrate the West's superior mass-manufacturing capabilities next to the Communists' relatively infrequent nuclear weapons tests. Any doubts in US dominance in the arms race brought up by the non-weaponized Ivy Mike device (described next), were erased by this steady stream of nuclear blasts. Poplar was the most explosive bomb (9.3 Mt.) in the series and was detonated on a barge off the coast of Bikini Atoll.
13 Ivy Mike
Not to be confused with the power behind 'Iron' Mike (Tyson)'s punches or the happy banana in Magic Mike's pants, this was the very first US run test of a two-stage thermonuclear device employing both nuclear fission and nuclear fusion. The 7.4 metric ton bomb was not dropped or launched or detonated in the air or under water, but built into a massive contraption the size of an airport hangar on Enewetak Atoll in the South Pacific. Soviet military personnel and scientists mocked Americans for building a bomb they could not transport, but the 10.4 megaton explosion and crater left in Enewetak Atoll suggest this Mike was no laughing matter.
12 Castle Romeo
Operation Castle was the name given to a series of thermonuclear device tests conducted or dropped on Bikini Atoll, which, like Enewatak mentioned above, was and still is part of the Marshall Islands chain. This was an atmospheric test meaning the bomb was detonated in the air as it fell to the earth and the 11 megaton yield of this device far surpassed military predictions due to unintended secondary atomic reactions. The photograph of Romeo's mushroom fireball, despite its relatively low megatonnage, has been held up by print media and in popular culture, for instance on a Megadeth album cover, as the archetypal nuclear blast.
11 Soviet Tests #147, #173, And #174
Most of the Cold War-era thermonuclear warheads tested by the U.S.S.R. were "dropped" or flown via Intercontinental Ballistic Missile to the Novaya Zemlya Test Site on a remote though not totally uninhabited archipelago in the Arctic Sea. ICBMs at minimum are designed to transport their radioactive payload from observation sites located over 3,400 miles (5,500 km.) away from the epicenter of the blast zone. All three weapons tested yielded a blast of approximately 20 megatons. The last Rüssky-run nuclear arms test occurred at the same site in 1990 after Communism fell and pressure to disarm mounted.
10 Castle Yankee, Castle Bravo
The middle-child of the Castle-series nukes tested on Bikini Atoll, Yankee, yielded a blast of 13.5 megatonnes, the second largest thermonuclear explosion recorded on US military territory. Castle Yankee was actually originally intended to be a test of a weaponized (a.k.a. mobile and deployable) version of Ivy Mike described above. This bomb, the EC-16, was hastily constructed to deal with the fact that the Yanks/US military had fallen behind on the ICBM front. Castle Bravo was a "dry fuel" hydrogen bomb and yielded 15 Mt. of explosive energy. With the weaponized Castle-series bombs proven successful, the EC-16s were dismantled.
9 Soviet Test #219
With a 6-mile blast radius and at 24.2 megatons, this nameless bomb was responsible for the second largest thermonuclear detonation in all of recorded history. The warhead was transported to or launched at the Soviet-run Novaya Zemlya Test Site via ICBM in 1962. Interestingly, the US Military were not devoting time or money to designing their own intercontinental payload-transporting rockets until the Russians started testing their hydrogen and fusion bombs with the help of ICBM technology in '53. This means that for a brief time the U.S.S.R. may have had a leg up in the arms race.
8 Tsar Bomb(a)
Just talking pure firepower and destructive capabilities, the Tsar Bomb (or Bomba in many Eastern European languages), this 50 megaton Russian warhead literally and figuratively blows the competition away and by a clear margin earns the title of most powerful detonation in history. This weapon was initially designed to deliver a 100 megaton blast, but military scientists concluded that no pilot/plane that existed at the time could carry such a massive bomb and clear the blast radius in time to survive (not to mention the risk of nuclear fallout).
7 The RDS-37: A Test Turns Deadly
Although this Russian-made atom bomb boasts the lowest megaton output of the nukes on the list, and was not intended to be harmful, two people lost their lives due to the detonation of this first ever two-stage H-bomb. Unexpected atmospheric conditions caused the bulk of the blast to be directed downward, causing tremors and some soldiers who were observing the test to collapse, killing one. What's worse is that, 40 miles (65 km) away, a building collapsed and killed an innocent girl. By some accounts the shockwave reached the observation site, 20 miles away, 90 seconds after detonation and personnel were forced to duck-and-cover to avoid injury by debris.
6 The 2009 Peshawar Bombing
News media tend to focus on the ongoing turmoil in the Middle East, the constant upheaval in the powder keg that is the Arab-Israeli world, forgetting that the root of the conflict, religions extremism and zealotry, is rampant across the globe but especially in the Eurasian steppes and South Asian countries, like Sri Lanka and Pakistan. On the 28th of October, 2009, a suicidal, presumably Sunni Pakistani man drove a truck full of homegrown explosives up to a police checkpoint and detonated himself. The explosion "only" killed 29 individuals and injured around 100 more but also created a 3 ft.-deep crater and led to the collapse of several buildings in the vicinity.
5 Habarana/Digampathana Massacre
In 2006, a different South East Asian conflict, not that between Sunni and Shi'ite Muslims, but the ongoing conflict between militant Tamil-descendant Sri Lankans and the ruling powers that flared up enough for international news outlets to take notice. A military convoy of 300+ Navy-men was en route between the cities of Habarana and Dambulla until they reached the smaller town of Digampathana, where a suicide truck bomb and its suicidal driver were waiting. The majority of the 100+ dead were sailors targeted by the "Tamil Tigers," self-described freedom fighters who have arguably unjustly terrorized the Sri Lankan government and its innocent citizens since 1976.
4 Sana'a Unity Day Bombing
Sana'a is a city in the Western half of Yemen, closer to the Red Sea side of the Arabian Peninsula. It is home to one of the few mosques known to the Western world that promotes a moderate form of Islam, and though it was built just eight years ago (2008), it stands, protected by police and bomb-sniffing dogs, as a testament to the possibility of practicing the Muslim faith in a way conducive to peace and progress. In true nihilist fashion, Al Qaeda claimed ownership of a single explosion that took out at least 120 innocents and moderates who were celebrating peace and the unification of their country.
3 The 2005 Al Hillah Bombing
On February 28th, 2005, this detonation of a (suicide) car bomb left 127 people dead and hundreds more injured. The attack targeted an Iraqi police force recruitment center that was abuzz with civilians hoping to join law enforcement to reestablish order in their war torn and dictator-ruined homeland. The Suni extremist-turned-epicenter had migrated from neighboring Jordan to throw in (the towel) with the Shia struggle; his Jordanian family supposedly held funeral services to the chagrin of Iraqi elements and the further detriment of Jordanian-Iraqi relations.
2 Oklahoma City Bombing
Just in terms of numbers killed by a single bit of ordinance, one man-made, intentionally harmful blast, the Oklahoma City Bombing still actually (but just barely) overshadows the death toll of any individual, rogue attack or single purposeful explosion created by violent elements across the globe. In the end, a homegrown terrorist proved to be a greater danger to North American citizens than any religious extremist or power/oil-hungry sheikh or despot. This detonation destroyed or damaged over 340 buildings within a 16-block radius of the epicenter and left 168 dead, and close to 600 non-fatally injured. The culprit was executed in 2005 and his accomplice is serving out a life sentence.
1 Little Boy, Fat Man
The one item on the list that involves multiple bombs, two to be exact, one (Fat Man) that devastated Nagasaki and the other (Big Boy) decimating the Japanese city of Hiroshima. We know the story, but what few know is that these bombs were firecrackers next to the weapons tested on deserted islands and in uninhabited tracts of desert in the US and the uninhabitable parts of the Soviet Union. On the order of kilotons instead of megatons, outside of the 20 Allied P.O.W.s that were deemed acceptable collateral damage, the real toll of dropping "the bomb" were broken diplomatic relations between West and East, a scorched earth, and irradiated genes/mutated offspring for generations to come.