At teleseismic distances, the first arriving P waves have necessarily travelled deep into the mantle, and perhaps have even refracted into the outer core of the planet, before travelling back up to the Earth's surface where the seismographic stations are located.
12.
The system became active in late June 2006 following the leadership of UNESCO . It consists of 25 seismographic stations relaying information to 26 national tsunami information centers, as well as 6 Deep-ocean Assessment and Reporting of Tsunami ( DART ) buoys.
13.
The authors are Thomas M . Brocher, ( CQ ) Jill McCarthy and Patrick E . Hart of USGS, W . Steven Holbrook of Woods Hole Oceanographic Institution in Massachusetts, Furlong of Penn State University, Thomas V . McEvilly of the University of California-Berkeley Seismographic Station and John A . Hole ( CQ ) and Simon L . Klemperer ( CQ ) of Stanford University.
