| The first scientific study of a tsunami as generated by a distant earthquake
can be traced to Bache [1856] who correctly identified waves from the 1854
Nankai earthquake on California tidal gauges. We will review developments
in the study of the relationship between earthquake source and far field
tsunami, with their logical application to distant warning.
Among the principal milestones, we discuss Hochstetter's [1869] work on the
1868 Arica tsunami, Jaggar's real-time, but ignored, warning of the
1923 Kamchatka tsunami in Hawaii, his much greater success with the 1933 Showa
Sanriku event, the catastrophic 1946 Aleutian event, which led to the
implementation of PTWC, the 1960 events in Hilo, and the 1964 Alaska tsunami,
which led to the development of the A[now N]TWC.
From the scientific standpoint, we will review the evolution of our
attempts to measure the seismic source (in practice its seismic moment),
always faster, and at always lower frequencies, culminating in the W-phase
inversion, heralded by Kanamori and co-workers in the wake of the Sumatra
disaster. Specific problems arise from events violating scaling laws, such
as the so-called "tsunami earthquakes", and we will review methodologies to
recognize them in real time, such as energy-to-moment ratios. Finally, we will
discuss briefly modern technologies aimed at directly detecting the tsunami
independently of the seismic source. |