Switch high voltage with triggered spark gap
Gas discharge tubes work like a spark gap, the difference is they have a gas encapsulated in glass. This lets you determine the breakdown voltage, whereas the breakdown of a spark gap in air would be different depending on conditions such as pressure, humidity, ect.

 
Source: http://g3ynh.info/disch_tube/intro.html

The circuit above may work, but you'd have to get a GDT that would trigger below the 10kV and above the voltage of the resistor divider.

Another option might be a triggered spark gap.