Seismology in Pasadena
After early astronomical work, Benioff joined the Carnegie seismological programme in 1924. He earned a Caltech doctorate in 1935, joined its faculty when the laboratory transferred there in 1937, and became a full professor in 1950.
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Recording ground motion
His sensitive seismographs and linear-strain instruments improved observations of wave arrivals and small ground changes. Adopted by observatories, they supported research on earthquakes, source processes and Earth vibrations.
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Earthquakes and trenches
Benioff used earthquake and aftershock distributions to investigate faults and ocean trenches. Wadati’s earlier mapping and Benioff’s later work became important for understanding subduction as plate tectonics developed; inclined seismic zones bear both names.