Video footage of scientists demonstrating the potential explosive power of devices used in the alleged 21 July attacks has been seen in court.
Woolwich Crown Court heard evidence from explosives expert Clifford Todd, whose team carried out the mock blasts.
He said they blew up replicas of the devices alleged to have been used by the defendants, containing a mix of chapatti flour and hydrogen peroxide.
Six defendants deny conspiracy to murder and to cause explosions.
Manfo Asiedu, Muktar Ibrahim, Hussein Osman, Yassin Omar, Ramzi Mohammed and Adel Yahya are accused of carrying out the failed attacks on the London transport system on 21 July 2005 as part of an extremist Muslim plot.
Mr Todd, principal forensic investigator from the Forensic Explosives Laboratory in Kent, had a large bucket-type device beside him as he appeared on the witness stand in the court.
He said this was identical to the devices his team had built - filling them with various mixes of chapatti flour and hydrogen peroxide - in an attempt to replicate the explosives the defendants are alleged to have made.
Nails and washers were taped around the bucket which the prosecution say were intended to be used as shrapnel.
The explosions seen on the video shown to the jury took place in a quarry, with scientists watching from a fortified bunker, the court heard.
A cloud of white smoke could be seen rising several metres into the air and a chair that was fixed to the device shattered into many pieces, landing a long way from the site.
Mr Todd said he could hear the explosion and feel the shockwaves from the bunker - visible as a "shimmer" on the court's television screens.
But he said the substance, triacetone triperoxide (TATP), used by the defendants was not an ingredient in the replica devices.
Mr Todd said: "No-one at this point in the world had actually tried putting an improvised detonator containing TATP in an improvised explosive mixture - it's just too dangerous."
The trial continues.