The IHDI reflects a nation's development based on all of the following factors EXCEPT a decent standard of living.
gender inequality.
access to knowledge.
the level of inequality.
a long and healthy life.

I think its a long and healthy life

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.

The peak above is part of the  sierra madre occidentals ,  a chain of volcanic mountains that runs through the middle of central america.