Scientific risk assessments of natural hazards are increasingly subjected to legal scrutiny, given the costly damage of such events (see, for example, Nature 548, 508–509; 2017). The reputations of the scientists, civil-protection managers and politicians tasked with reducing societal risk are on the line should these assessments prove inadequate. The prospect of litigation should help to foster better mitigation practices.

The 2014 eruption of Mount Ontake in Japan killed at least 58 people (see Nature http://doi.org/cdwp; 2014). Civil claims by bereaved families against Japan's Meteorological Agency and the Nagano prefecture government are ongoing. Unlike the legal proceedings against scientists and government officials following the 2009 earthquake in L'Aquila, Italy (see Nature 477, 264–269; 2011), these claims are not criminal prosecutions. They are for monetary compensation from government entities, similar to the successful 2013 civil claims in Chile after a tsunami in 2010 (R. J. Bretton et al. J. Appl. Volcanol. 4, 18; 2015).

As claimants test the timeline of circumstances leading up to such disasters, scientific records and legal duties of care will be subject to intense scrutiny from peers, lawyers and the media. Earth scientists must confront these pressures with rigorous data monitoring, analysis and interpretations, combined with accurate public communication of any scientific uncertainties.