MPM cannot run with threads> 2

I install MPM based on the instruction using the following compile command.
cmake -DCMAKE_BUILD_TYPE=Release -DKAHIP_ROOT=~/workspace/kahip/ -DPARTIO_ROOT=~/workspace/partio/ -DHALO_EXCHANGE=On …

Everything goes well. But I cannot analysis using threads> 2
For example:
This is OK
./mpm -p 2 -i mpm.json -f /home/mqx/benchmarks/3d/dam-break/
However, if the threads> 2 as foollows:
./mpm -p 28 -i mpm.json -f /home/mqx/benchmarks/3d/dam-break/
The error information is
[2021-01-15 15:14:10.636] [MPMBase] [warning] /home/mqx/mpm/include/solvers/mpm_base.tcc #71: Velocity update parameter is not specified, using default as false
[2021-01-15 15:14:10.636] [MPMBase] [warning] /home/mqx/mpm/include/solvers/mpm_base.tcc #94: No math functions are defined
[2021-01-15 15:14:10.636] [MPMBase] [warning] /home/mqx/mpm/include/solvers/mpm_base.tcc #135: No VTK variables were specified, none will be generated
[2021-01-15 15:14:10.637] [MPMBase] [warning] /home/mqx/mpm/include/solvers/mpm_base.tcc #166: No VTK statevariable were specified, none will be generated
[2021-01-15 15:14:10.637] [MPMExplicit] [info] MPM analysis type MPMExplicit3D
[2021-01-15 15:14:10.638] [MPMExplicit] [info] Rank 0 Read nodes: 1 ms
[2021-01-15 15:14:10.639] [MPMExplicit] [warning] #831: Euler angles are undefined Euler angles JSON not found
[2021-01-15 15:14:10.639] [MPMExplicit] [warning] #935: Friction conditions are undefined Friction constraints JSON not found
Segmentation fault (core dumped)
I have already install the gcc 9.3, but the openMP iis not 5.0

echo |cpp -fopenmp -dM |grep -i open

The output is
#define _OPENMP 201511

What can I do to solve this problem.