Crowdsourcing　is　a　new　paradigm　of　service　provision.　Current　commercial　crowdsourcing　platforms　rarely　consider　the　interaction　between　task　takers,　which　is　extremely　required　in　the　disaster　management　scenario.　In　this　paper,　we　designed　a　framework　for　community　based　crowdsourcing,　i.e.,　task　takers　are　from　an　existing　community　or　will　easily　form　a　new　community.　A　size-specified　community　creation　method　using　multiple　social　contexts　is　also　proposed.