My research covers five related areas involving the use of seismic data to investigate Earth structure and processes over a range of scales, from the deep mantle to the surface. Tightly integrated with my research is an education effort to improve diversity in the geosciences.
AfricaArray: AfricaArray is a multifaceted initiative supporting science education and research in Africa and the U.S. built around interrogating the largest geophysical anomaly in Earth’s mantle to advance our understanding of its origin, structure, composition and influence on mantle dynamics and surface processes (http://africaarray.psu.edu). The AfricaArray network of 53 permanent geophysical observatories in 17 African countries provides seismic, GPS and weather data openly to the community. Many temporary seismic networks have been deployed over the past 15 years to improve data coverage between the observatories.
Antarctica: For almost 20 years I have been investigating the structure and origin of geologically intriguing regions of Antarctica, including the Transantarctic Mountains, the Gamburtsev Subglacial Mountains, the Marie Byrd Land Dome, and the West Antarctic Rift System, using seismic data from temporary and permanent networks. Current efforts are part of the multi-institutional POLENET project (http://polenet.org), where seismic and GPS data from a backbone network of more than 30 stations distributed throughout West Antarctica are being used with data from temporary stations to image details of crust and mantle structure beneath large glaciers that have the potential to collapse catastrophically as the planet warms and cause several meters of sea level rise.
Appalachian Basin: Connected to the operation of the Pennsylvania State Seismic Network (PASEIS: http://paseis.geosc.psu.edu) is a research effort to assist the mitigation of seismicity caused by hydraulic fracking and wastewater disposal. Induced seismicity in the Appalachian Basin (PA, OH, WV) is occurring in areas where the depth to crystalline basement under the sedimentary cover is fairly shallow (< ~ 4 km). A new “basement” map is needed to improve risk assessments by regulatory agencies and the development of seismic monitoring requirements. Seismic data from the PASEIS network, in conjunction with data from other networks, regional 2D industry seismic reflection profiles, and well logs, are being used to map the depth to basement across the Appalachian Basin. The same data are also being used to investigate Precambrian crust and lithospheric mantle structure beneath the basin to improve our understanding of North American continental structure.
Critical Zone: The critical zone extends from the vegetation canopy downwards to unweathered bedrock, a zone of the earth “critical” for supporting life. To understand key physical and geochemical processes at the watershed scale within the critical zone that transform bedrock into soil, 3D and 4D (i.e., time lapse) geophysical imaging of the shallow subsurface is needed. Over the past few years, I have developed a new research thrust to obtain and interpret electrical resistivity and active and passive source seismic data to image the critical zone at Susquehanna Shale Hills Critical Zone Observatory.
Andriampenomanana, F., A. A. Nyblade, M. E. Wysession, R. J. Durrheim, F. Tilmann, G. Barruol, M. Pratt, G. Rambolamanana, and T. Rakotondraibe, Seismic velocity and anisotropy of the uppermost
mantle of Madagascar from Pn tomography, 2020, Geophysical Journal International, doi.org/10.1093/gji/ggaa458.
White-Gaynor, A., A. Nyblade, R. Durrheim, R. Raveloson, M. van der Meijde, I. Fadel, H. Paulssen M. Kwadiba, O. Ntibinyane, N. Titus, and M. Sitali, 2020, Lithospheric boundaries and upper mantle structure beneath southern Africa imaged by P- and S-wave velocity models, Geochemistry, Geophysics and Geosystems, doi: 10.1029/2020GC008925
Lucas, E. M., D. Soto, A. A. Nyblade, A. J. Lloyd, R. C. Aster, D. A. Wiens, J.P. O’Donnell, G. W. Stuart, T.J. Wilson, I. Dalziel, J. P. Winberry, and A. D. Huerta, 2020, P- and S-wave velocity structure of central West Antarctica: Implications for solid earth-ice interactions and the tectonic evolution of the West Antarctic Rift System, Earth and Planetary Science Letters, doi: 10.1016/j.epsl.2020.116437
Emry, E.L., A. A. Nyblade, A. Horton, S. E. Hansen, J. Julià, R. C. Aster, A. D. Huerta, J. P. Winberry, D.A. Wiens, S. Anandakrishnan, and T. J. Wilson, 2020, Prominent thermal anomalies in the mantle transition zone beneath the Transantarctic Mountains, Geology, doi: 10.1130/G47346.1.
Emry, E., Y. Shen, A. Nyblade, A. Flinders, and X. Bao, Upper mantle earth structure in Africa from full-wave ambient noise tomography, 2019, Geochemistry, Geophysics and Geosystems, doi: 10.1029/2018GC007804
Ramirez, C., A. Nyblade, M. Wysession, M. Pratt, F. Andriampenomanana, and T. Rakotondraibe, 2018, Complex seismic anisotropy in Madagascar revealed by shear wave splitting measurements, 215, 1718-1727, Geophysical Journal International, doi: 10.1093/gji/ggy367.
Nyblade joined the Penn State faculty in 1994 after completing a National Science Foundation postdoctoral fellowship at Penn State. He is a founder and co-Director of AfricaArray, and also serves a co-Director of the Marcellus Center for Outreach and Research (MCOR) and Director of the Pennsylvania State Seismic Network (PASEIS). He is the recipient of many honors and awards. At Penn State he has received the President’s Award for Excellence in Academic Integration, the Diversity Recognition Award, and the Wilson Award for Outstanding Service from the College of Earth and Mineral Sciences. He is a Fellow of the American Geophysical Union, and is also the recipient of the Paul G. Silver Award for Outstanding Scientific Service from the American Geophysical Union.
He holds B.A. degrees in geology and earth science education from Wittenberg University, a M.S. degree in geophysics from the University of Wyoming, and a Ph.D. degree in geology from the University of Michigan.