New Delhi, Dec. 11: An American seismologist highly-rated in geological circles but labelled by some as a “scaremongerer” has said that the Indian government has, under the influence of a senior Indian scientist, banned his entry into India.

Roger Bilham, a University of Colorado geophysicist, who was sent back from New Delhi airport on May 19 this year while in transit to Bhutan, has said that he learnt again last week that he is still on a list of foreigners not permitted to enter India.

Sections of Indian scientists familiar with Bilham’s work say his research studies on earthquake hazards in the subcontinent have generated controversy in India, but said they are surprised at the government’s decision to keep him out of India.

Bilham and a collaborating Bangalore-based geophysicist Vinod Gaur had suggested that Indian authorities might have underestimated the seismic risk at the site of a proposed nuclear power station in Jaitapur, Maharashtra.

Over the past decade, Bilham has predicted that the Himalayan region is ripe for several giant earthquakes greater than magnitude 8, and cautioned that any one of these could kill more than a million people in the densely populated urbanised Gangetic plains.

“It’s unfortunate if Bilham has been barred entry because of his scientific views,” said Rangachar Narayana Iyengar, an earthquake engineering expert in Bangalore and the former director of the Central Building Research Institute in Roorkee.

“Differences of opinion in science must be allowed, indeed encouraged — that is the way science advances,” Iyengar told The Telegraph.

Bilham, who has visited India at least six times over the past decade, first learnt he was on a list of unwanted foreigners on the night of May 19 when he was sent back to the US from New Delhi airport while he was trying to fly to Bhutan for a field trip.

Bilham, who has a 10-year multiple-entry tourist visa from India, said he had written about his deportation to the US state department on May 21, which informed him on May 22 that it had learnt that he was on a list of individuals not permitted to visit India.

“They were not told why I was on the list. I enquired again last week because I was planning to visit Delhi to study historical archives,” Bilham told The Telegraph via email. “They confirmed that I was still on the prohibited list.”

Indian home ministry officials have not responded to email queries from The Telegraph, seeking information about the circumstances under which the government had decided to keep Bilham out of India.

But Indian scientists say they are intrigued by a claim made by Bilham in writing to the Indian Institute of Science (IISc) in Bangalore that the government appears to have been influenced by a senior Indian seismologist.

“The government decision was presumably based on recommendations made by one or more influential seismologists in India,” Bilham wrote to the IISc on October 17 this year, in a letter where he has declined to evaluate the PhD thesis of a young scholar.

The IISc had requested Bilham to assist in the evaluation of the thesis.

“It has been brought to my attention that some younger colleagues have been intimidated by a retired (Indian) seismologist who once held a position in Hyderabad, from working with me, or being associated with scientific studies, or discussions,” Bilham told the IISc.

“The intimidation takes the form of suggestions that future funding, or chances of promotion, or job security, may be placed in jeopardy if these young scientists are in any way associated with my name,” he wrote, adding that his presence on the panel of thesis examiners might turn detrimental to the future of the young scholar.

Shailesh Nayak, secretary in the Union earth sciences ministry said he had no direct information about the decision to keep Bilham out of the country. “My understanding is that it has something to do with his tourist visa,” Nayak said.

But Bilham said he has never had a problem with his visa.

In January this year, he was invited to an Indo-US bilateral workshop on intraplate seismicity at Gandhinagar, Gujarat, a meeting supported by the Indo-US Science and Technology Forum, an initiative funded by the Indian and US governments.

A senior Indian geophysicist who knows Bilham well said his research and style of making presentations in India may have irked sections of senior scientists. “I have had a good working relationship with him, but he’s regarded by some as a scaremongerer,” said Bal Krishna Rastogi, director of the Institute of Seismological Research in Gandhinagar, which hosted the workshop . “It’s not nice for scientists to come here and tell us that we’re not doing anything. Whatever might be lacking in our efforts here is because of (lack of) resources.”

Bilham’s deportation from India also featured at the American Geophysical Union meeting on December 6 where Max Wyss, a Switzerland-based seismologist, mentioned it as an example of scientists being punished for predictions.

Gaur said the decision to disallow Bilham from visiting India is “against the philosophy of science”, which, he said, demands honest, open debates. “When science gets closed to scrutiny, there is a danger that it might get done with less rigour.”

Iyengar said he’s also concerned about the impact to young scholars. “Seismic risk is a borderline area of human knowledge — disagreement about hazard risks are always present, but punishing someone who holds a contrary view might turn young people away from seismology.”