Nars: Over 30 Years of Seismology

Abstract:

It is fair to say that modern seismology steadily evolved from a handful key initiatives and innovations dating back to the early 1980s.

(1) The transition from non-mobile, narrow band sensors with analogue recording (pre-1980s) to portable, broadband sensors with digital recorders paved the way to flexible deployments, enabling various array and regional studies with the same instrumentation. Here I mention just two initiatives: NARS, which was the first digital, mobile network of broadband stations deployed in western Europe (1983-1987), and USarray (2003- ), which is the biggest program of recent times. Presently, innovative data acquisition systems for the oceans are underway and they will allow future imaging of the "inaccessible" parts of the Earth.

(2) In the 1980s seismological data centers were set up to facilitate data archiving and distribution. Since then, open data exchange (not a matter of course) and easy data retrieval have become standard. The impact of this has been phenomenal: most observational studies efficiently retrieve data from these main seismological data centers and the archived seismograms are used for various types of studies, carried out by different persons and groups.

(3) Seismic tomography changed the face of seismological research. From travel time to waveform tomography, from ray theory to finite frequency tomography: new and improved tomographic techniques greatly enhanced our images (and understanding) of the Earth's interior.

(4) Many of these developments would not have been possible without young, motivated, seismologists that were educated and stimulated by insightful supervisors.

One person has had a major impact on all these fields. NARS in the title stands for Nolet greatly Advanced Research in Seismology.