Earthquake insurance is designed to cover large-scale structural damage, and I understand the deductible is very high. Would you even need it, as a renter?
I suppose for coverage of your "stuff," though I wonder whether you would be able to get a policy for contents rather than structure and contents, and what the deductible would be (compared to the value of stuff that could get broken in an earthquake).
If you do look into this, check first to see whether your current policy would cover damages that happen collaterally from an earthquake, ie flooding due to a broken water pipe, fire due to broken gas pipe.
I lived through a pretty major earthquake as a renter - the neighbor's brick chimney fell through our living room roof and ceiling - but our TV and other electronics (only high price stuff we had) were fine. Fun fact: our dishes slid out of the overhead kitchen cupboards, and fell into the drawers of kitchen towels underneath. Not a single dish broken! But our fridge door opened and all the food fell out of that, so that was gross.