What observation complicates modeling the location of Io's internal heating relative to its volcanoes?

Answer

A systematic eastward offset between predicted heating and observed eruptions

Analysis shows that the most intense volcanic activity is observed significantly eastward of where current models predict the greatest internal heating should occur.

What observation complicates modeling the location of Io's internal heating relative to its volcanoes?
GeologyJupitermoonsVolcanismTidal heatingIogeological activity