Sorry, this is bogus. The earthquake did not affect the earth's rotation.
But the length of the day has been getting longer since the moon was created 4.4 billion years ago. The moon's gravity causes a slight drag on the rotation through the tides and angular momentum.
The day was about 15 hours long 4.4 billion years ago to today where it is 24 hours long.
Over those 4.4 billion years, how many magnitude 9.0 earthquakes have there been? If there was one every 30 years which sounds about right and it added 3 microseconds to the day or off the day, the day would be well over 1,000 hours long or there would be no day.
I hate junk science.
From the USNO earth orientation website http://maia.usno.navy.mil/eop.html
"It is also possible that a large earthquake might affect polar motion, but to date, this effect has not been observed closely."
A mouse scurrying across the room changes the rotation of the earth. The earthquake will not measurably effect the earth's angular momentum, but if it changes the moments of interia, the rate will change, maybe just a wee bit.
Three microseconds corresponds to about 3 parts in ten billion change in the earth's moment of interia. Could be possible.