  The evolution of the fireball resulting from the August 2020 Beirut explosion
is traced using amateur footage taken during the first $\sim$ 230 $ms$ after
the detonation. 38 frames separated by $\sim$ 16.66 - 33.33 $ms$ are extracted
from 6 different videos located precisely on the map. Measurements of the time
evolution of the radius $R_{t}$ of the shock wave are traced by the fireball at
consecutive time sequence $t$. Pixel scales for the videos are calibrated by
de-projecting the existing grains silos building for which accurate drawings
are available and by defining the line of sight incident angles. The energy
available to drive the shock wave at early times can be calculated through $E =
10^{2b} K \rho_{o}$ where $b$ is a fitted parameter dependant on the relation
between $R_t$ and $t$. $K$ is a constant depending on the ratio of specific
heats of the atmosphere and $\rho_0$ is the undisturbed gas density. A total
energy yield of $E \approx 1.3\times 10^{12}$ Joules with a lower bound of
$9.8\times 10^{11}$ and an upper bound of $\sim 1.7\times 10^{12}$ or the
equivalent of $\sim 310_{235}^{405}$ tons of T.N.T. is found. Our energy yields
are different from other published studies using the same method. This can
present an argument that if the compound that exploded is fuel rich ammonium
nitrate (ANFO), then the actual mass that detonated is less than officially
claimed.
