diff --git a/src/write_global_output.f90 b/src/write_global_output.f90
index 9caca12e53749c62328098fe147793de8f788cd2..de0f318728ed80e5f07ec6f2e372b4c944aea40b 100644
--- a/src/write_global_output.f90
+++ b/src/write_global_output.f90
@@ -196,18 +196,23 @@ if (iproc.eq.0) then
                 cl%tag(i),    &
                 i=1,cl%np)
 
-   if (params%isobc) then 
-     ! write isostasy basal displacement array - dwhipp 11/09 
-       write (9) 2**params%levelmax_oct
-       write (9) ((zi%zisodisp(i,j)+surface(osolve%nlsf)%sp01,&
-                 j=1,2**params%levelmax_oct+1),i=1,2**params%levelmax_oct+1) 
+   ! write isostasy basal displacement array - dwhipp 11/09
+   write (9) 2**params%levelmax_oct
+   if (params%isobc) then
+     write (9) ((zi%zisodisp(i,j)+surface(osolve%nlsf)%sp01,                   &
+               j=1,2**params%levelmax_oct+1),i=1,2**params%levelmax_oct+1)
+   else
+     write (9) ((0.d0+surface(osolve%nlsf)%sp01,j=1,2**params%levelmax_oct+1), &
+               i=1,2**params%levelmax_oct+1)
    end if
 
+   ! write nested model info - dwhipp 05/11
    if (params%nest) then
-     ! write nested model info - dwhipp 05/11
      write(9) nest%sselemx,nest%sselemy,nest%sselemz,nest%xminls,nest%yminls,&
               nest%zminls
-    endif
+   else
+     write(9) 0.d0,0.d0,0.d0,0.d0,0.d0,0.d0
+   endif
 
    close (9)