Pro-establishment voices on Persian-language social media claim a recent earthquake in Iran’s Semnan Province was actually a covert nuclear test, with ultra-hardliners calling for Iran to pursue nuclear deterrence capabilities.

“It seems that there was no earthquake but a nuclear test in Semnan two nights ago … Now [can you imagine] what would happen if that explosion occurred on the ground in Israel?” one of them asked.

The post referred to an earthquake of 4.4 magnitude on the Richter scale at a depth of 12 km, according to Tehran University’s Geophysics Institute, in Semnan Province that was felt as far as the capital Tehran.

The tremor was also recorded as an earthquake by the US Geological Survey which put its magnitude and depth at 4.5 on the Richter scale and 10 km respectively.

Despite the recorded depth of the seismic activity, many Persian-language social media users on major platforms like X and Telegram, as well as domestic platforms such as Eitaa, are calling the tremor proof of an Iranian nuclear test.

“I feel proud … Iran unveiled its magical mushroom—felicitations to all whose hearts beat for Iran,” a pro-establishment netizen tweeted.

“An Iranian bomb is our inalienable right,” another tweet with the hashtag #بازدارندگی_اتمی (nuclear deterrence), which many others have been extensively using in recent days, read.

“Our people have the right to enjoy nuclear deterrence. Have the courage to take the historical decision [to go nuclear],” a tweet addressed to the authorities that claimed the country’s nuclear program has so far cost $2,000 billion to the nation declared.

“It’s true that the decision to build a nuclear weapon and whether it is religiously banned or not lies with the Leader ... When there is talk of building nuclear weapons, it is for a balance of power and deterrence, not actual use,” another netizen tweeted arguing that Pakistan developed nuclear capabilities only after India built its bomb “to deter threats and [create] balance.”

The tweet referred to the Iranian state's official argument, based on Supreme Leader Ali Khamenei's often disputed nuclear fatwa, that Iran has never sought nuclear weapons because he has religiously banned all weapons of mass destruction, including nuclear bombs. Many experts have also disputed the legitimacy of this fatwa, given Iran's rapid advancement of its nuclear program raising concerns about its intentions.

Other individuals on X argued that the religious ban could and must be lifted to allow Iran to revise its nuclear doctrine.

Many other netizens, however, have refuted the claim that the tremor Saturday was the result of an underground nuclear test, pointing out that a nuclear test could not have been carried out at the depth recorded by seismological organizations.

Ultra-hardliners who fervently circulated the rumor Sunday on Telegram channels and X appear to have taken their inspiration from several tweets in English that suggested Iran may have conducted a nuclear test Saturday.

These, including a tweet by DD Geopolitics and ConflictX, based their argument on the false premise that an Armenian seismology station had picked up the tremor first and claimed that a comparison between typical earthquake vibrations and nuclear tests suggested the event resembled a nuclear test.

Several Armenian news outlets including News.am that reported the earthquake, however, had quoted Tehran University’s Geophysics Institute as their source, not an Armenian seismological station as these and similar tweets claimed.

In another tweet, DD Geopolitics displayed a graph that compared earthquake and explosion pairs, suggesting that real earthquakes were followed by several lesser tremors (aftershocks). In contrast, nuke tests by Pakistan, India, North Korea, and Soviet Union did not.

DD Geopolitics is an online media outlet run by an allegedly pro-Russian former US Navy veteran, Sarah Bills, who has been accused of running social media accounts “notorious for spreading disinformation about the war [in Ukraine]”.

“The report of a nuclear test in the desert in Semnan [Province] is not true. But it is noteworthy that many Iranians paid attention to it and in comparison, many welcomed it more than before, Mostafa Najafi, Tehran-based Ph.D. candidate in international relations at Toronto Metropolitan University tweeted.

“The idea and demand for building a nuclear weapon has grown recently following the recent increase in the level and range of threats against Iran, especially from countries with nuclear weapons, and it is being spoken of more often in official and unofficial circles,” Najafi wrote.