Hi Canie - No... No typo there.

"2) Theoretically quakes cannot occur below 70 kms (due to rocks getting packed ever tighter due to presumed rising temperatures and pressures with depth...thus closing off all cavities...and causing rock to flow under such stress). Above a certain pressure (presumed matched with depths of several hundred kms) , lab experiments show that brittle fracture is prohibited as well as frictional sliding processes."

Temperature and Pressure per theory does not allow earthquakes below 70 (not 700) km. That's why an earthquake at 700 km (or 71 km for that matter) is a mystery...since either the theory of the earth's pressure/temperature with depth is incorrect OR the definition of "What an earthquake is" is incorrect (or the seismic wave interpretation is incorrect).

If no brittle fracture can occur because the rock is flowing then what are people measuring when a deep focus earthquake happens ? The interpretation of the seismic wave energy relies on wave propagations as a function of depth (accounting for temperature / and pressure per current theory). If these asssumptions are wrong then both are open to new interpretations.

Just maybe Both/all ideas are incorrect.

Food for thought,

Just my $.02 worth