lava flow distances
 

What are the variables neccesary to establish a basic formula to determined the averaged maximum distance a lava flow may travel?

I ask because I live on Kilauea volcano in Hawaii and we have had a vent named Pu'u O'o that has been in a state of constant eruption for 31 years now. It is currently flowing on it's North flank and the surface flows only seem to travel about 5 miles before stopping and starting over again at the vent.

Keep in mind that an eruption may consist of many different flows. So the rule of thumb statistically speaking on the north of flank is 5 miles of flow then a reset occur. The eruption does not stop.

On the south flank where the grade is steeper, the flows travel 10 miles to the ocean and continue for long periods of time as in month or years.

What are the variables and properties within the flows that dictate these exhibited behaviors? Obviously, grade, viscosity, temperature, mass, etc are to be considered but what else and how would a semi reliable formula be formatted?

Thanks for any input in advance.

One of the attributes here is also how lava travels over a surface of its own material in a solidified/cooled state. The lava creates it's own tube and melts the bottom of its tube and sinks lower into the ground over time of the flow. Given there are different densities and sometimes materials (dirt) in the surface and subsurface the flow travels over, the tubes may take on drops and rises created by its actions creating eddie currents within the tubes that may also cause back pressure at the source.