Don't we have some sort of technology to confirm this?

World Net Daily:  Sabotage! Key Iranian nuclear facility hit? Source: Explosion destroys much of underground installation
"According to a source in the security forces protecting Fordow, an explosion on Monday at 11:30 a.m. Tehran time rocked the site, which is buried deep under a mountain and immune not only to airstrikes but to most bunker-buster bombs. The report of the blast came via Hamidreza Zakeri, formerly with the Islamic regime’s Ministry of Intelligence and National Security,"

Sunday Times:  Iranian uranium-enriching facility ‘is damaged by explosion’
"An explosion is believed to have damaged Iran’s Fordow nuclear facility, which is being used to enrich uranium, Israeli intelligence officials have told The Times. Sources in Tel Aviv said yesterday that they thought the explosion happened last week. The Israeli Government is investigating reports that it led to extensive structural damage and 200 workers had been trapped inside."

Jerusalem Post:  Ex-CIA man: Iran blast largest sabotage in decades
"Although it has not yet been verified, a report by Iranian dissident-turned CIA operative Reza Kahlili, which said a massive blast rocked Iran’s key Fordow nuclear installation last week, continued to spread on Monday."

BBC:  Iran denies reports of explosion at Fordo nuclear site
"Iran has denied foreign media reports of a major explosion at one of its underground uranium enrichment sites."

 Jerusalem Post:  Ya'alon: 'I read about Iran blast in the paper'
Strategic Affairs Minister and Vice Premier Moshe Ya'alon said Monday that he had read in the newspaper about the alleged explosion at Iran's Fordow Iranian nuclear facility...In an interview with Army Radio, Ya'alon refused to comment specifically on reports of a mysterious blast at the underground bunker, only commenting that "in the past we heard about worms and viruses and explosions. Every incident like this delays Iran's nuclear program...According to the original report of the mysterious blast, penned by former Iranian Revolutionary Guard, Reza Kahlili, for the WND.com website, the explosion “destroyed much of the installation and trapped about 240 personnel deep underground."

Die Welt:  Expert reports severe explosion at nuclear plant
"Now, the "Welt am Sonntag", however, has received from an Iranian intelligence service contacts with experts confirmed that the explosion had actually happened. After this information is not 240, but was nevertheless completed about 190 workers at the nuclear plant from the outside world."

World Net Daily:  New details surface on Iran nuclear explosion
Lots of new details here.

Reuters:  U.S. does not believe media reports about blast at Iranian enrichment plant
"We have no information to confirm the allegations in the report and we do not believe the report is credible," [White House spokesman Jay] Carney said. "We don't believe those are credible reports."

So did the explosion occur or not?  The evidence..

• "No comment" from Israel generally means they were involved.  
• The fact that the story was reported in World Net Daily generally means the story is bullshit.

Don't we have some sort of seismic sensing technology that would have detected a massive blast?