Question

what is the cause of the surat split​

Answer 1

Moderates believed in the policy of settlement of minor issues with the government by deliberations. But the extremists believed in agitation, strikes and boycotts to force their demands. Some nationalists led by Lokmanya Tilak agitated against the moderate behaviour of congress against British rule.

Answer 2

because Shivaji plundered it twice
and
also
because of the growing power of mumbai ,kolkata and chennai led it to split