diff --git a/doc/USER_MANUAL/05_running_the_solver.tex b/doc/USER_MANUAL/05_running_the_solver.tex
index 08a5eb024..ef3e70409 100644
--- a/doc/USER_MANUAL/05_running_the_solver.tex
+++ b/doc/USER_MANUAL/05_running_the_solver.tex
@@ -234,7 +234,7 @@ \chapter{Running the Solver \texttt{xspecfem3D}}\label{cha:Running-the-Solver}
 \end{figure}
 
 In addition to inbuild source-time functions, the solver can also use an external source-time function defined by the user. This option can be activated by setting \texttt{USE\_EXTERNAL\_SOURCE\_FILE} to \texttt{.true.} in \texttt{DATA/Par\_file} and by adding the name of the file containing the source-time function at the end of \texttt{FORCESOLUTION} or \texttt{CMTSOLUTION} files.
-The source-time function file must contain a single column with the amplitudes of the source-time function for all the time steps. The time step must be exactly the same as that used for the simulation. When the flag is set to \texttt{.false.}, then the line with the external source-time function file must not appear in the files \texttt{FORCESOLUTION} and \texttt{CMTSOLUTION}, otherwise the solver will exit with an error. When using an external source file, you can still set up the source location and directivity as in the default case.
+The source-time function file must contain a single column with the amplitudes of the source-time function for all the time steps. The time step must be exactly the same as that used for the simulation. If the external source-time functions are same for all the sources, differing only in their respective time shift, you can define the source-time function file only for the first source and set the external source-time function file to 'reuse' and define the appropriate value of \texttt{time shift} for all the other sources. When the flag is set to \texttt{.false.}, then the line with the external source-time function file must not appear in the files \texttt{FORCESOLUTION} and \texttt{CMTSOLUTION}, otherwise the solver will exit with an error. When using an external source file, you can still set up the source location and directivity as in the default case.
 In the \texttt{FORCESOLUTION} file: you set "latorUTM", "longorUTM" and "depth" to define the position of your point source. Then if you want to define a directivity, change the following lines: "component dir vect source E", "component dir vect source N" and "component dir vect source Z\_UP". What you are doing is simply that you define the source position and directivity the same way as in the default case, but in addition you are specifying the path to read in a non-default source-time function from an external file.
 
 \vspace{1cm}
diff --git a/src/specfem3D/get_force.f90 b/src/specfem3D/get_force.f90
index 3f10291f6..979107227 100644
--- a/src/specfem3D/get_force.f90
+++ b/src/specfem3D/get_force.f90
@@ -53,6 +53,7 @@ subroutine get_force(FORCESOLUTION,tshift_src,hdur,lat,long,depth,NSOURCES, &
 
   ! local variables below
   integer :: isource,ier,ipos,dummyval
+  integer :: ishift,nright
   double precision :: t_shift(NSOURCES)
   double precision :: length
   character(len=7) :: dummy
@@ -199,9 +200,21 @@ subroutine get_force(FORCESOLUTION,tshift_src,hdur,lat,long,depth,NSOURCES, &
       ! gets external STF file name
       read(IIN,"(a)") string
       external_source_time_function_filename = trim(string)
-
-      ! reads in stf values
-      call read_external_source_time_function(isource,user_source_time_function,external_source_time_function_filename)
+      if(trim(external_source_time_function_filename).eq.'REUSE' .or. &
+         trim(external_source_time_function_filename).eq.'Reuse' .or. &
+         trim(external_source_time_function_filename).eq.'reuse')then
+        ! Reuse the source time function of the first source.
+        if (isource.eq.1) then
+          stop 'Error: "reuse" option cannot be used for the first source!'
+        endif
+        ishift=nint(t_shift(isource)/DT)
+        nright=NSTEP_STF-ishift
+        user_source_time_function(1:ishift,isource)=0.0_CUSTOM_REAL
+        user_source_time_function(ishift+1:NSTEP_STF,isource)=user_source_time_function(1:nright,1)
+      else
+        ! reads in stf values
+        call read_external_source_time_function(isource,user_source_time_function,external_source_time_function_filename)
+      endif
     endif
 
     ! checks Par_file flag to override type setting