Typically it's a hundred yards on either side of a high voltage line. And with the liabilities P&G is facing, I'd clear cut a hundred yards on either side of medium voltage lines too.
That's a 1km^2 of cleared forrest for every 10 km of line. California has (tens of?) thousands of km of lines.
Which of course the fires are going to burn no matter what PG&E does. “But for an electrical spark” is a great way to lay the blame but ignores the hundreds (thousands?) of forest fires each year that start from non-electric sources.
In the scale of the maintenance required to have zero risk of fire — hundreds of billions of dollars — the $4 billion in dividends is a rounding error.
CA is going to have to do the math and decide it’s not worth $100 billion in guaranteed economic depression due to cutting power to try to save a 5% chance of a $100 billion fire.
CA is also going to have to do the math that no one is going to pay to maintain a grid that’s fire proof but charges $3/kWh for power.