In the past 30 days there have been a total of 25 Earthquakes near Dallas, Texas. 16 of the 19 Earthquakes happened in Irving with three others happening in University Park, Midlothian and Farmers Branch. According to Earthquake Track, only two reached a magnitude over 3 (3.6 and 3.1).
Currently in North Texas, Earthquake is not a covered peril on most homeowner policies. A few companies offer an endorsement adding the coverage, but not all. Two insurance companies, Travelers and Met Life Auto and Home do offer the endorsement.
The cost of the endorsement is roughly 20% of your premium with a minimum deductible of 10% of the insured amount. That is not a typo. If you have a home insured for $250,000, than you would have a minimum $25,000 earthquake deductible.
The cost of purchasing a separate earthquake policy is even more expensive with even higher deductibles. My feeling is more companies will begin offering the coverage which will hopefully drive down the cost.