A rescue worker runs on a street cracked by a powerful earthquake that struck Kumamoto prefecture on April 16, 2016.Credit: Kazuhiro Nogi/AFP/Getty

Authors of a study in Science analysing an earthquake that struck Kumamoto in southern Japan in 2016 have retracted their paper, following a university investigation that found it contained falsified data and manipulated images.

In a retraction notice published1 on 2 May, Science cited a Kyoto University probe, which could not determine whether the errors were deliberate but found that responsibility for them lay with Aiming Lin, the corresponding author and a professor at the university. Lin did not respond to Nature’s request for comment on the investigation's conclusions.

The paper, published in November 2016, purported to show that Mount Aso, one of the world’s largest active volcanoes and situated roughly 30 kilometres northeast of Kumamoto City, had halted the rupture zone of a magnitude-7.0 earthquake on 16 April, and prevented it from spreading further and causing more damage than it did. The quake killed more than 50 people and damaged in excess of 190,000 buildings.

The paper’s data and figures showed a 40-kilometre-long rupture zone that ended inside Mount Aso’s caldera, a depression that forms when a volcano collapses in on itself, and at a depth consistent with the volcano’s magma chamber. The authors concluded that the thick magma inside the chamber had stopped the rupture — which could also make the volcano more likely to erupt in the future.

Misconduct allegations

But according to Kyoto University, where five of the six authors were based, a whistle-blower reported possible misconduct associated with the study in August 2017. The university initiated an investigation, which found falsifications in two figures and plagiarism in one of them, it announced on 26 March.

In the two figures, data overlaid on three maps were stretched, distorted or rotated in ways that supported the paper’s hypothesis. In one panel, the outline of Mount Aso’s caldera was shifted, making the rupture seem to travel further inside it than the data showed. The investigation also found that the dates on which some data had been collected were changed to better fit the study’s hypothesis.

The﻿ investigation's committee could not determine whether the distortions were intentional, but found Lin had breached his obligation as a researcher. According to The Japan Times, Lin told the investigators that the paper's conclusions were not wrong.

The university cleared the other five authors of any wrongdoing.

Lin's is the second group to have research about the Kumamoto earthquake retracted. In March, a study published in Seismological Research Letters by scientists from Osaka University in Japan was retracted following a university investigation. The investigators found that the lead author, Yoshiya Hata, had fabricated data in this paper and four others, but cleared his coauthors.

Hata resigned from the university in December 2017, but﻿ died before the investigation began in February last year. Another study, published in the Bulletin of Seismological Society of America, was also retracted in March after the coauthors notified the journal that it also contained fabricated data from Hata.