The number seems very low, but I believe that estimate has been misinterpreted by english sources. The figure comes from a Chinese Earthquake monitoring organi

The number seems very low, but I believe that estimate has been misinterpreted by english sources. The figure comes from a Chinese Earthquake monitoring organisation, and it seems to say that the energy of the earthquake was equivalent to 21 tons of TNT. The bulk of the energy in the explosion would've dissipated through the air, and wouldn't be involved in the earthquake at all.