The AntarcticArray: Implications for Studies of Earth's Core and Deep Mantle

The deployment of an Antarctic Array of permanent and temporary broadband 
seismic stations will have a major impact on the studies of the Earth's
lowermost mantle and core, in particular, the inner core.

Inner core anisotropy: The source of inner core anisotropy is still
poorly understood and recent studies have suggested complex structure
of inner core anisotropy. However, critical samples of the inner 
core along NS direction (polar paths) are rare, because of 
few earthquake source region in the high latitude in the Southern
Hemisphere.  From earthquakes in high latitudes in the Northern Hemisphere,
an Antarctic Array will provide not only polar samples of the inner core, 
but also more uniform lateral and depth coverage of the inner core. 
These polar paths will provide critical new samples to image
3D structure of the inner core anisotropy.
 
Inner core rotation: The South Pole station (SPA) is one of the oldest of
seismic stations of the world.  Because of its long history of continuous 
recording and the availability of polar paths, SPA has been used to 
detect inner core rotation. PKP travel times from earthquakes in
southern Alaska to SPA have been shown to change over time, indicating 
inner core rotation (Song and Li, 2000).  The rotation rate was estimated 
about 0.6 deg/yr faster than the mantle from this data set. 
The AntarcticArray will be useful in mapping the fine structure of the 
inner core, which is needed to further constrain the rotation rate, and 
the continuous operation of SPA will be important in
monitoring such inner core motion.