LCSN, People, Nano (Leonardo) Seeber




Nano (Leonardo) Seeber,
Doherty Senior Research Scientist
Lamont-Doherty Earth Observatory
Palisades, NY 10964

Tel: 845-365-8385
Fax: 845-365-8150
E-mail: nano@ldeo.columbia.edu

Nano (Leonardo) Seeber

As a graduate student in the mid 1960's, I worked on the design and construction of one of the first portable seismographs: Transportable as backpack and recording on smooke paper. The main motivation was to record many small earthquakes up close and thus obtain a detailed view of tectonic processes. Tomography has a unique role in resolving subsurface structure. I continue to be primarily interested in high-resolution imaging of seismicity to monitor the first derivative of structure. Earthquakes illuminate faults in action; they are very sensitive indicators, as well as agents of changes in mechanical state. Small earthquakes offer the best chance of detecting changes precursory to large earthquakes. Models of interaction between brittle and the viscoelastic lithospheric deformation, poroelastic response, state and rate-dependent friction, are examples of critical experiments that will be carried out with such data. Another issue ripe for major advances based on near-field observation of earthquake sources is tectonics and seismogenesis of stable continental regions (SCR). SCR deform very slowly, slower than the current measurement resolution (10-10), yet SCR seem to produce earthquakes from many ubiquitous very low-rate sources. This is consistent with the near-failure stress found pervasively in SCR. Understanding this behavior is a research challenge and a major issue for hazard. The characteristics of seismogenic faults; the role of pre-existing geologic structure; the depth distribution of seismogenesis, how engineering activities trigger earthquakes, etc., are some of the topics that can advance understanding of SCR seismogenesis if investigated on the basis of good near-field observations of earthquake sources. Thus, I think we need to re-think deployment strategies in the East. Permanent networks have a role, but they need to be integrated with "continually deployed portable networks" that target active sources. Besides detailed information on source characteristics, this strategy offers the opportunity to obtain critical nearfield data on damaging, or potentially damaging ground motion in SCR. Other recent topics:

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Nano Seeber, Lamont-Doherty Earth Observatory of Columbia University, copyright©1999, all rights reserved