Article History
Received: 10 July 2015
Accepted: 5 April 2016
First Online: 9 May 2016
Change Date: 13 May 2016
Change Type: Corrigendum
Change Date: 9 June 2016
Change Type: Corrigendum
Change Details: In the version of the Article originally published, the link in the 'Data and code sources' section of the Methods was incorrect and should have been 'ExternalRef removed'. This has been corrected in all versions of the Article.
Change Details: In the version of the Article corrected on 13 May 2016, the location of the data accessed via the link provided in the 'Data and code sources' section of the Methods proved unsuitable. The link has now been removed and the isostatic and spherical harmonic inversion codes are available on request from the corresponding authors. This information has been corrected in the online versions of the Article.
Competing interests
: The authors declare no competing financial interests.