Positions are liquidated using KyberSwap. When a trader goes under margin maintenance (15%), they are only partially liquidated, bringing their current margin to 25%.
By only liquidating as much as is necessary, the risk of slippage from excessively large liquidations is reduced. Anyone can initiate a margin call. It is a process that is permissionless and incentivized. The incentive to liquidators is the a refund of your gas * 2. There’s also no capital carrying costs/risks you’d experience liquidating on the other protocols.
This ensures that there are redundancies in the margin calling process. Moreover, there is an insurance fund which protects lenders. In the case that a lender would lose principal, the insurance fund will automatically disburse funds to the lender. This insurance is funded by a smart contract holding 10% of all interest that is paid by borrowers to lenders.