On Her Majesty's Secret Service

In Portugal, James BondÂ â agent 007, sometimes referred to simply as '007'Â â saves a woman on the beach from committing suicide by drowning, and later meets her again in a casino. The woman, Contessa Teresa "Tracy" di Vicenzo, invites Bond to her hotel room to thank him, but when Bond arrives he is attacked by an unidentified man. After subduing the man, Bond returns to his own room and finds Tracy there, who claims she didn't know the attacker was there. The next morning, Bond is kidnapped by several men, including the one he fought with, who take him to meet Marc-Ange Draco, the head of the European crime syndicate Unione Corse. Draco reveals that Tracy is his only daughter and tells Bond of her troubled past, offering Bond a personal dowry of one million pounds if he will marry her. Bond refuses, but agrees to continue romancing Tracy under the agreement that Draco reveals the whereabouts of Ernst Stavro Blofeld, the head of SPECTRE.
Bond returns to London, and after a brief argument with M at the British Secret Service headquarters, heads for Draco's birthday party in Portugal. There, Bond and Tracy begin a whirlwind romance, and Draco directs the agent to a law firm in Bern, Switzerland. Bond investigates the office of Swiss lawyer Gumbold, and learns that Blofeld is corresponding with London College of Arms' genealogist Sir Hilary Bray, attempting to claim the title 'Comte Balthazar de Bleuchamp'.
Posing as Bray, Bond goes to meet Blofeld, who has established a clinical allergy-research institute atop Piz Gloria in the Swiss Alps. Bond meets twelve young women, the "Angels of Death", who are patients at the institute's clinic, apparently cured of their allergies. At night Bond goes to the room of one patient, Ruby, for a romantic encounter. At midnight Bond sees that Ruby, apparently along with each of the other ladies, goes into a sleep-induced hypnotic state while Blofeld gives them audio instructions for when they are discharged and return home. In fact, the women are being brainwashed to distribute bacteriological warfare agents throughout various parts of the world.
Bond tries to trick Blofeld into leaving Switzerland so that MI6 can arrest him without violating Swiss sovereignty. Blofeld refuses and Bond is eventually caught by henchwoman Irma Bunt. Blofeld reveals that he identified Bond after his attempt to lure him out of Switzerland, and tells his henchmen to take the agent away. Bond eventually makes his escape by skiing down Piz Gloria while Blofeld and his men give chase. Arriving at the village of Lauterbrunnen, Bond finds Tracy and they escape Bunt and her men after a car chase. A blizzard forces them to a remote barn, where Bond professes his love to Tracy and proposes marriage to her, which she accepts. The next morning, as the flight resumes, Blofeld sets off an avalanche; Tracy is captured, while Bond is buried but manages to escape.
Back in London at M's office, Bond is informed that Blofeld intends to hold the world to ransom by threatening to destroy its agriculture using his brainwashed women, demanding amnesty for all past crimes, and that he be recognised as the current Count de Bleuchamp. M tells 007 that the ransom will be paid and forbids him to mount a rescue mission. Bond then enlists Draco and his forces to attack Blofeld's headquarters, while also rescuing Tracy from Blofeld's captivity. The facility is destroyed, and Blofeld escapes the destruction alone in a bobsleigh, with Bond pursuing him. The chase ends when Blofeld becomes snared in a tree branch and injures his neck. Bond and Tracy marry in Portugal, then drive away in Bond's Aston Martin. When Bond pulls over to the roadside to remove flowers from the car, Blofeld (wearing a neck brace) and Bunt commit a drive-by shooting of the couple's car; Bond survives, but Tracy is killed in the attack. A police officer then approaches Bond's car, Bond looks at the police officer. All choked up, Bond says: "it's all right, it's quite all right really. She's having a rest, we'll be going on soon. There's no hurry you see, we have all the time in the world....." Bond starts to cry, and cradle Tracy's body.

Question: What does Blofeld set off ?
Answer: Blofeld sets off an avalanche .