Almost all energy released in earthquakes is released in the biggest ones. No realistic number of smaller quakes is ever going to add up to even the single biggest earthquake ever recorded.
To dissipate the energy of a M9 (which happens about once per decade) you'd need about 32,000 quakes of M6 (still big enough to collapse buildings).
Energy scales as 10^(1.5 × ΔM)
ΔM = 9.0 − 6.0 = 3.0
10^(1.5 × 3) = 10^4.5 ≈ 31,600
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