Current Status and Forecast. n Tropical Pacific sea-surface temperatures (SSTs) have warmed from La NiÃ±a. Modoki (below-average SSTs, centered in the central tropical Pacific) to ENSO-neutral. Current SSTs range from slightly below average in the central Pacific to slightly above. average in the eastern Pacific. n The Climate Prediction Center (CPC) defines a La NiÃ±a event as having ONI values. of -0.5Â°C or colder for 5 consecutive months.
Convection currents move tectonic plates when there is heat inside the mantle that is rising and falling. The radioactive decay in the core is responsible for the convection currents.
The lithospheric plates rest on top of the solid, but plastic, lower Mantle or Asthenosphere. Scientists believe that convection currents in the Asthenosphere, due to the Earth s escaping heat, provide the driving force of Plate movement. There are three types of Plate movement Convergence, Divergence, and Transform.