Hi
Liquidation is triggered both by the price of Ethereum and the Collateralization ratio. Bank loans use a LTV or loan-to-value ratio to determine how much to loan you. The MakerDao uses a Collateralization ratio, which is the inverse of loan-to-value. So instead of having 80,000 loan/ 100,000 home value, they have home value/loan value and call it a Collateralization ratio and it liquidates your assets at ratio 1.5 or below. So the price of EThereum is important, but also how much you borrowed. If you have a thousand Ethereum and borrow 500, your Collateralization ratio is 2.0, so Ethereum price would have to drop more for you to trigger liquidation then someone who borrowed more and ratio was 1.6 or 1.7. Then the smart contract sells off enough Ethereum to return ration to >1.5. Usually it’s around 66% of your Ethereum.