type bboxchange
$( selector ).geomap( {
  bboxchange: function( e, geo ) { }
} );
$( selector ).bind( "geomapbboxchange", function( e, geo ) { } );
} );

The bboxchange event triggers any time user interaction causes a change in the current bbox of the map widget. This includes pan, wheel zoom, double-click zoom, etc. The geomap does not trigger this event when you update the bbox programmatically.

The geo argument is an object containing a bbox property which the new bbox.