Government spending, 2009 and on, surged (consistently and permanently above 3.5T every year, compared to 2-3T before 2008)). Revenue dropped (except for 2012) to slightly above 2T. Deficit = "revenue-spending", so yearly deficit obviously increased to above 1T.
Please note that these figures did NOT include spending on wars in Iraq and Afghanistan, which would have pushed the spending as well as deficit up by ~$120-150B a year (The Pentagon's total allocation for war from 2001-2011 in current dollars was $1,208.1 based on CBO), so actual deficits would have been north of $300B yearly before 2008, not $200B, to compare apples to apples.
Now, if you are curious what drove the spending increases that helped along this high deficit, let's look at the #s behind the graphs below in 9 spending categories - although, the graphs should give a very good idea even without the tables.
But here's the data, hopefully self explaining.
Most of the increase (NOT diminished at all) vs. 2008 was Welfare spending, followed by Seniors , then Defense, followed by Other (which was mostly high in 2009, likely due to TARP).
P.S. On a side note, as I figured out here, despite the $800B figure for TARP, in reality it was just over $400B, and all but $17-18B of it was paid back to the Treasury by 2013.