Per 
D.P.N.2 (Drilling Project Number 2: Alaskan Variant)
Item #: SCP-2012
Object Class: Keter
Special Containment Procedures: SCP-2012 Is too incredibly large to contain in a normal manner, we have stopped it from breaking through the crust and have done extensive procedures in keeping it under control. We have found that using electrical surges through multiple drilling holes keeps it tamer.
Description: Little is known, currently, about the capabilities of the mass. It is an estimated 13.5 x 2.3 miles surface area, and an unknown deepness (presumably 400-500 miles below the crust). It was discovered directly underneath the Earth's crust by accident, after a possible absence of rock was picked up below the surface via experimentation with a new sonar-like device. We had picked up something similar to this before, back in 1972 in Siberia, but our drilling machinery failed to go beneath the crust. We thought it was just a fault in the new device (it was still only in the pre-alpha testing stage).
Years passed, and we are now close to completing the device. But we picked up the absence again, this time it had grown to a huge size, and had moved near Alaska. With the new ability to break through the Earth's crust, we could access new intel on the organism. It was liquid-like, the substance however it was made out of was unknown. It is probably jet-black, after throwing a camera down the hole we could catch a glimpse of the color. How it got here? We don't know. The age could be 50 years to millions of years.
It's growing. At some point, our electrical surges will fail to stop it. Eventually, it will break through. We can't stop it then.
