This fruit is fearsomely reputed to be able to destroy the world, and is considered to be the strongest Devil Fruit within the Paramecia class, having powers no weaker than those of a Logia Devil Fruit.
The major strength granted by this fruit to the user is its ability to generate massive vibrations, or shockwaves, which can travel through virtually any medium, including the ground, the seafloor, and even the air. Because of this, Fleet AdmiralSengoku has stated that Whitebeard holds the power to destroy the world, and Vice-AdmiralTsuru stated that, even if she retreated to the ends of the ocean, there would be no safe place left in the world for her to go when faced with the power of the Gura Gura no Mi.
The user of this fruit can devastate an entire island with ease, although their limitations are noticeable: it took repeated usages to come close to destroying the Marine base at Marineford (in fact, Whitebeard failed to do so before dying, and Blackbeard almost completed the task); the shock waves were blocked by the siege wall, albeit one made from an especially strong metal superior to ordinary steel or seastone; and Admiral Aokiji easily stopped the tsunami that Whitebeard created. It should be noted, however, that only after Ace's death did Whitebeard truly attempt to erase Marineford in his anger, but it was Blackbeard who truly was willing to destroy the island using both of his Devil Fruit powers. Although neither man succeeded in sinking the island, with both having been stopped and the latter lacking enough control over the power, the resulting aftershocks and tsunami were felt far away from Marineford.
When Blackbeard took this Devil Fruit's power through an unknown method, he claimed that with the power of quakes which "brings destruction to all" combined with the darkness that "reduces anything to nothingness", he was truly invincible and the strongest.
However, this Devil Fruit's powers are noted to be a hazard to both friend and foe alike, as observed by both the Whitebeard and Blackbeard Pirates. This primarily stems from how, even though the user seems to be able to control both the magnitude of the shock wave and its point of impact, the quakes produced by these shock waves are indiscriminate in their effects. Because of this, allies of the user must be prepared for the impacts unless they want to become unintended victims of them.
This Devil Fruit has no apparent weakness, aside from the standard Devil Fruit weakness. However, the three Admirals managed to stop Whitebeard's shockwaves from hitting Marineford's execution platform by combining their Busoshoku Haki. Also, the siege wall that Sengoku planted was composed of a material which Whitebeard's shockwaves could not shatter. Additionally, as mentioned previously, due to the fact that Whitebeard's attacks were indiscriminate in who they could hit, his allies and crewmates had to fight a certain distance away from him, giving enemies far more room in attacking him.
Whitebeard demonstrated four separate, distinct techniques with his Devil Fruit, and could also imbue the direct contact techniques with Busoshoku Haki to attack Logia users at close range. None of his attacks are named in the manga or anime, but are named in the game One Piece: Gigant Battle.
Kaishin (海震,Kaishin?, literally meaning "Seaquake"): Whitebeard "cracks" the air with a punch and sends devastating shock waves through the air in the direction it is facing. These shock waves can pass through and damage almost any substance, tearing it apart. If the shock waves are directed into the ground, the result is a devastating earthquake capable of generating huge tsunamis. Because of its enormous offensive power and great speed, this attack makes for a solid defense, destroying or disrupting any attack before it hits Whitebeard, who first used it this way to defend against Aokiji's ice-spears. However, this technique is not unblockable, as the siege walls in Marineford are made of a special material that can resist damage and diffuse the power of this attack. Additionally, the three Marine Admirals prevented this attack from reaching the execution platform by blocking it with a "shield" of their combined Busoshoku Haki. This technique is called Seaquake in the English localization of One Piece: Burning Blood.
Gekishin (激震,Gekishin?, literally meaning "Severe Earthquake"): A close range variant of Kaishin. Whitebeard directly cracks the air in front of an enemy, causing severe damage as the shockwaves directly pass through their bodies, as John Giant and Akainu both suffered. Whitebeard could also passively summon vibrations around himself, which protected him from being frozen by Aokiji due to vibrations not being freezable.
Shingen no Ichigeki (震源の一撃,Shingen no Ichigeki?, literally meaning "Hypocenter Attack"): Whitebeard focuses vibrations around his fist in an spherical bubble to form an earthquake hypocenter and delivers a punch releasing all the force concentrated at once, with enormous power. In the anime, he also created such a bubble on his foot for a devastating stomp.
Kabutowari (兜割,Kabutowari?, literally meaning "Helmet Splitter"): A variant of Shingen no Ichigeki. Instead of delivering a punch, Whitebeard grabs his opponent's head and concentrates his vibrations around it, resulting in crushing damage. He first used this technique to defeat the giantVice-AdmiralRonse in a single blow. This technique is called Oscillating Throw in One Piece: Burning Blood.
Naginata Rasetsu (薙刀羅刹,Naginata Rasetsu?, literally meaning "Mowing Blade Rakshasa"): Whitebeard surrounds his naginata, the Murakumogiri, with a quake bubble to greatly increase its striking power and range.
Shima Yurashi (島揺らし,Shima Yurashi?, literally meaning "Island Shaking"): Whitebeard "grabs" an entire area, by grabbing and pulling on the air around him as if it were tangible, and rapidly shifts it. Using this, he tilted the entire island of Marineford and the sea around it, destroying buildings and throwing a giant off of his feet in the process. This technique is called The Man Who Shakes the World in One Piece: Burning Blood.
Video Game-only Attacks
Ikkitosen (一騎当千,Ikkitōsen?, literally meaning "Matchless Warrior" or "Mighty Hero"): Whitebeard swings Murakumogiri, sending waves of vibrations at his opponents. This was first used in One Piece: Pirate Warriors . It is one of Whitebeard's special moves and requires one special gauge to perform. In the game's English release, the technique is called One Man Army.
Tenchi Meido (天地鳴動,Tenchi Meidō?, literally meaning "Heaven and Earth Rumbling"): Whitebeard grabs the air and pulls it downwards; once he gets low enough, all of his opponents are tossed into the air and fall back down. This was first used in One Piece: Pirate Warriors 2. It is one of Whitebeard's special moves and requires two special gauges to perform. It is similar in execution to Shima Yurashi but does not tilt the earth itself. It is also used by Blackbeard, who needs only one special gauge to perform the attack. In the game's English release, the technique is called Heaven and Earth.
Strongest Rampage: Following a jump, Whitebeard slams down on the ground sending vibrations into it causing a small earthquake where he lands. This technique appears as Whitebeard's special movement in One Piece: Burning Blood.
Silent Rage: Whitebeard charges his power into his hand then punches the opponent smashing them into the ground unleashing vibrations, then attacks the opponent with his naginata several times before flinging the opponent into the air. Finally, pulling back his arm, he charges a Kaishin which he hits the opponent with at point blank in mid-air as they are falling back to the ground. This technique is Whitebeard's Ultimate attack/Super move in One Piece: Burning Blood.
Marshall D. Teach
Blackbeard can use all of the abilities that Whitebeard did in addition to his Yami Yami no Mi powers, but he still lacks the mastery of the fruit that Whitebeard had. Teach has demonstrated the usage of Kaishin,Kabutowari and Shima Yurashi.
At some point in his life, Whitebeard ate the Gura Gura no Mi. The destructive power that this fruit granted him contributed to his being known as the strongest man in the world.
Although Whitebeard died, the Gura Gura no Mi did not return to circulation due to exceptional circumstances. His killer, Blackbeard, used an unknown procedure while covered by a black cloth to somehow transfer the ability into himself. This became a phenomenon that was met with shock and horror at a global scale, as not only was Blackbeard the first and so far the only person known to possess two Devil Fruit powers without his body exploding, but he destroyed the world's relief at believing that the threat of the Gura Gura no Mi is over by demonstrating his new-found powers, causing even more grief.
This is the first Devil Fruit to be shown to belong to two separate users, having been acquired by Marshall D. Teach after the death of Edward Newgate, via an as-of-yet undisclosed method. Furthermore, it now shares a distinction with the Yami Yami no Mi as the first two fruits to be wielded concurrently by the same user.
The Gura Gura no Mi's power is one of the two aspects that made Whitebeard resemble the Greek God Poseidon, the other being his status as an Emperor, as the emperor of the seas who could cause earthquakes and tsunamis.
The idea of a Devil Fruit that would allow someone to create tsunamis was first brought up when Morgan explained what Devil Fruits are.
The Hasshoken style utilized by the Happo Navy and Chinjao Family is similar to the Kabutowari technique Whitebeard used, surrounding their strikes with vibrations to shatter defenses, though the Hasshoken style is more of concentric waves emitted from the strike, while the Kabutowari technique is a bubble of focused seismic energy.
↑One Piece Manga and Anime — Vol. 59Chapter 577 (p. 3-5 & 13-17) and Episode 486, Blackbeard steals the power of the Gura Gura no Mi and demonstrates it, shattering the observers' hopes that the Gura Gura no Mi was no longer a threat.
↑One Piece Anime — Episode 3, Morgan speaks about Devil Fruit users who can breath fire and create tsunamis.
Shock Wave – Wikipedia article about waves controlled by the user.
Vibration – Wikipedia article on the anomaly controlled by the user.