Trenching

Our research is focused on earthquakes and active tectonics

Earthquakes are amongst the most devastating of natural hazards, and anticipating their locations, timings, and magnitudes is one of the grand challenges of geophysics. Much can be learned by studying the surface expression of earthquake faulting through the twin disciplines of tectonic geodesy (how Earth's surface deforms during or between earthquakes) and geomorphology (how landscapes evolve over many earthquake cycles), which complement the traditional field of instrumental seismology (the study of seismic waves propagating through the earth). We work across these disciplines to better understand the mechanics of deformation from the scale of individual earthquake ruptures to mountain belts and entire plate boundary systems.

Our work is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation (CFI), the BC Knowledge Development Fund, the Yukon Geological Survey, Natural Resources Canada, and the Canada Research Chairs program. We are also grateful to Petroleum Experts Ltd. for donating their MOVE software to our lab (equivalent to £1.9M).

Some current topics of focus are listed below:

• Mechanics of large earthquake ruptures

Modern geodetic and seismological imaging tools provide powerful insights into the earthquake rupture process. We have studied the evolution of slip in space and time of several recent, large earthquakes, helping us better understand how slip nucleates, propagates, and is arrested. One of our most interesting observations has been cascading earthquakes that "jump" from fault to fault across wide (~10s of km) gaps, which was not previously thought possible. We are also interested in the role of fault structural maturity in controlling rupture properties including off-fault deformation and shallow slip deficits.


Harnai interferogram


Fault image

• Uncharacteristic earthquakes

A common assumption in seismic hazard models is that active faults host quasi-periodic 'characteristic earthquakes' (after Schwartz & Coppersmith, 1984) that are limited in length and magnitude by persistent segment boundaries and which supposedly occur at rates higher than implied by the classic Gutenberg-Richter distribution. However, many of our own observations call this into question. For example, we've shown that the Eastern Anatolian fault (in Turkey) involves a mix of single- and multi-segment earthquakes, and that the Papatea and Jordan faults (in New Zealand) ruptured in the 2016 Kaikoura earthquake with different slip, lengths and kinematics than in older events.


Example publications:

Langridge et al. (2023): Late Holocene earthquakes on the Papatea Fault and its role in past earthquake cycles, Marlborough, New Zealand. Accepted, New Zealand Journal of Geology and Geophysics

Howell et al. (2020): 3D surface displacements during the 2016 Mw 7.8 Kaikōura earthquake (New Zealand) from photogrammetry-derived point clouds. Journal of Geophysical Research: Solid Earth

Pousse-Beltran et al. (2020): The 2020 Mw 6.8 Elazığ (Turkey) earthquake reveals rupture behavior of the East Anatolian Fault. Geophysical Research Letters



• Differential lidar

Repeat high-resolution topographic data offer the capability to map earthquake surface displacements at high spatial resolutions, 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 shallow slip in the first wave of earthquakes spanned by before/after lidar topography, including notable events in Japan, California, and New Zealand.


Lidar image


Our lidar drone

• Drone lidar for tectonic geomorphology

We have developed a state-of-the-art lidar drone system for mapping fault zone topography at centimeter-scale resolutions even in the presence of dense vegetation. The system integrates a RIEGL miniVUX-1UAV laser scanner, an Applanix APX-20 UAV inertial navigation system, and a DJI Matrice 600 hexacopter. We have been trialling it on a number of active faults and landslides across heavily forested BC and the Yukon. The project is funded by the Canada Foundation for Innovation, the BC Knowledge Development Fund, and the Yukon Geological Survey.


Example publication:

Finely et al. (2022): Preliminary results and structural interpretations from drone lidar surveys over the Eastern Denali fault, Yukon. In: Yukon Exploration and Geology 2021 K.E. MacFarlane (ed.), Yukon Geological Survey



• Active tectonics of Cascadia and the Canadian Cordillera

The tectonics of western Canada and neighboring parts of the US provide an assortment of intriguing targets for study. Current foci include (1) the role of upper plate faulting (newly identified in lidar imagery) in deformation of the Cascadia forearc; (2) use of sea-floor geodesy in revealing patterns of strain accumulation on the Cascadia megathrust; (3) reassessment of the Queen Charlotte plate boundary, the world's foremost ocean-continent transform system; (4) earthquake potential of the Rocky Mountain Trench-Tintina and eastern Denali faults; and (5) diffuse deformation across the Yakutat collision zone and Alaskan cordillera.


Cascadia


Zagros by satellite

• Earthquakes and active tectonics of 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 deadliest on record. 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, and triggering.


Example publications:

Nissen et al. (2022): A reappraisal of active tectonics along the Fethiye-Burdur trend, southwestern Turkey. Geophysical Journal International

Nissen et al. (2019): The 12 November 2017 Mw 7.3 Ezgeleh-Sarpolzahab (Iran) earthquake and active tectonics of the Lurestan arc. Journal of Geophysical Research: Solid Earth

Karasözen et al. (2019): Seismotectonics of the Zagros (Iran) From Orogen‐Wide, Calibrated Earthquake Relocations. Journal of Geophysical Research: Solid Earth