|Some current topics of focus are listed below. |
Rupture complexity in large earthquakes
advances in geodetic and seismological imaging (including those
described in the next project) provide powerful new insights into the
rupture process of large earthquakes. We have used these tools to
investigate patterns of shallow slip, off-fault deformation and fault
segmentation in several recent earthquakes. These rupture
characteristics are of critical importance for earthquake physics, for
interpreting paleoseismic data, and for forecasting future earthquakes.
One of our most interesting observations has been cascading earthquakes
that "jump" from fault to fault across wide (~10s of km) segment
boundaries, which was not previously thought possible.
Some key papers:
• Clark, K. J., Nissen, E. K.,
Howarth, J. D., Hamling I. J., Mountjoy, J. J., Ries, W. F., Jones, K.,
Goldstien, S., Cochran, U. A., Villamor, P., Hreinsdóttir, S.,
Litchfield, N. J., Mueller, C., Berryman, K. R., and Strong, D. T.
(2017). Highly variable coastal deformation in the 2016 Mw 7.8 Kaikōura earthquake reflects rupture complexity along a transpressional plate boundary. Earth and Planetary Science Letters, 474, 334-344.
• Nissen, E.,
Elliott, J. R., Sloan, R. A., Craig, T. J., Funning,
G. J., Hutko, A.,
Parsons, B. E., and Wright, T. J. (2016). Limitations of rupture
forecasting exposed by instantaneously triggered earthquake doublet. Nature Geoscience, 9, 330-336.
high-resolution topographic data offer
the capability to map earthquake surface displacements at high spatial
resolution, in three dimensions, and without loss of coherence even
amongst steep deformation gradients close to surface faulting. We have
developed and are applying these emergent techniques to characterize
in the first wave of earthquakes spanned by "before" and "after" lidar
topography, including notable events in Japan, California, and New
Some key papers:
• Scott, C., Arrowsmith, J R., Nissen, E., *Lajoie, L., Maruyama, T., and Chiba, T. (2018). The
M7 2016 Kumamoto, Japan, earthquake: 3D deformation along the fault and
within the damage zone constrained from differential topography. Journal of Geophysical Research: Solid Earth, 123, 6138-6155.
• Nissen, E.,
Maruyama, T., Arrowsmith, J. R., Elliott, J. R., Krishnan, A. K., Oskin, M. E.,
and Saripalli, S. (2014). Coseismic fault zone deformation revealed
with differential lidar: examples from Japanese Mw ~7 intraplate earthquakes. Earth and Planetary Science Letters, 405, 244-256.
• Nissen, E., Krishnan, A. K., Arrowsmith, J. R., and Saripalli, S. (2012). Three-dimensional surface displacements and rotations from differencing pre- and post-earthquake LiDAR point clouds. Geophysical Research Letters, 39, L16301.
Active tectonics of northwestern North America
tectonics of western British Columbia and its neighboring regions
provide an assortment of intriguing targets for study. From South to
North, these include (1) the role of upper plate faulting (newly
identified in lidar imagery) in deformation of the Cascadia forearc;
(2) patterns of strain accumulation and release on the Cascadia
megathrust, as will soon be revealed using sea-floor geodesy; (3) plate
boundary reorganization offshore northern Vancouver Island; (4) the
Queen Charlotte fault, the world's foremost ocean-continent transform
boundary; and (5) diffuse deformation across the broad Yakutat
collision zone. Over the next few years I hope that we will make
contributions in all these areas - watch this space!
Active tectonics and earthquake hazards in the Middle East
Located within the Arabian-Eurasia plate boundary zone,
Turkey and Iran contain a
dense concentration of
large-magnitude earthquakes, including several of the most damaging ever recorded. By studying
recent earthquake sequences using high-resolution earthquake
relocations, waveform modelling and InSAR, we
are investigating continental extensional (Western Turkey) and
collisional (Iran) tectonics and patterns of seismicity, aftershocks,
Some key papers:
• *Karasözen, E., Nissen, E., Büyükakpınar, P., Cambaz D., Kahraman, M., Kalkan, E., Abgarmi, B., Bergman, E., Ghods, A., and Özacar, A. A. (2018). The 2017 July 20 Mw 6.6 Bodrum-Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey. Geophysical Journal International, 214, 185-199.
• Howell, A., Jackson, J., Copley, A., McKenzie, D., and Nissen, E. (2017). Subduction and vertical coastal motions in the eastern Mediterranean. Geophysical Journal International, 211, 593-620.
• Nissen, E., Tatar, M., Jackson, J. A., and Allen, M.B. (2011). New views on earthquake faulting in the Zagros fold-and-thrust belt of Iran. Geophysical Journal International, 186, 928-944.
Active faulting in Mongolia
within the northernmost India-Eurasia collision zone and has hosted
several of the largest continental
ruptures ever recorded. It contains a dense network of active faults
that are clear in satellite imagery but whose
individual slip rates and earthquake chronologies are poorly
known. We are using field work, sampling and Quaternary dating to
determine active fault slip-rates within the Mongolian Altay mountains,
in turn helping illustrate its unusual mode of shortening (anastomosing
strike-slip faults and vertical-axis block rotations). A bonus of this
work has been new age constraints on alluvial fan aggradation and
regional Quaternary paleoclimate.
Some key papers:
• Walker, R. T., Wegmann, K.W., Bayasgalan, A., Carson, R. J., Elliott, J., Fox, M., Nissen, E.,
Sloan, R. A., Williams, J. M., and Wright, E. (2017). The Egiin Davaa prehistoric rupture,
central Mongolia: a large-magnitude normal faulting earthquake, on a
reactivated fault with little cumulative slip, in a slowly-deforming
intraplate setting. In “Seismicity, Fault Rupture and Earthquake Hazards in Slowly Deforming Regions” (eds. Landgraf, A., Stein, S., and Hintersbergen, E.), Special Publication of the Geological Society of London, 432, 187-212.
• Nissen, E., Walker,
R., Bayasgalan, A., Carter, A., Fattahi, M., Molor, E., Schnabel, C.,
West, A. J., and Xu, S. (2009). The late Quaternary slip-rate of the
Har-Us-Nuur fault (Mongolian Altai) from Cosmogenic 10Be and
Luminescence dating. Earth and Planetary Science Letters, 286, 467-478.
• Walker R., Nissen, E., Molor, E., and Bayasgalan, A. (2007). Reinterpretation of the active faulting in central Mongolia. Geology, 35, 759-762.