Surface displacements in the September 2005 Afar rifting event from satellite image matching: Asymmetric uplift and faulting

Combining sub‐pixel analysis of SPOT4 images with InSAR measurements, we generate 3D surface displacements for the September 2005 rifting event on the Dabbahu Segment in the Afar valley. The axis of rifting in the event is shifted to the east of the geomorphic rift. The horizontal displacements reveal 6 m of extension, and vertical displacements show asymmetric uplift of the flanks of the dike. Simple forward modelling indicates this asymmetry is due to the dike dipping 80° to the west towards the geomorphic rift. The boundary between eastward and westward displacements aligns with the transition between uplift and subsidence on the east in the north part of the segment, but on the west in the south. Normal faulting is not required on both sides of the instantaneous rift. East‐dipping normal faulting on the west side of the instantaneous rift aligns with a west‐dipping normal fault in the topography

Seismically-induced mass movements and volumetric fluxes resulting from the 2010 Mw=7.2 earthquake in the Sierra Cucapah, Mexico

The observation that sediment flux from mountain ranges struck by high magnitude earthquakes can be strongly influenced by coseismic mass movements brings into question the nature of coseismic deformation as a net contributor to mountain building. To better constrain the role of high-magnitude earthquakes in orogenesis, high-resolution data of earthquake induced mass wasting is required for areas of differing tectonic, morphological, and climatic settings. Here we compare the erosional flux to the tectonic flux associated with the 2010 Mw = 7.2 Sierra El Mayor earthquake in Mexico and examine the landslide patterning of coseismic mass movements associated with this event. The ruptured fault system has a significant strike-slip component with subsidence along the eastern flank and uplift on the western flank of the range. Peak ground acceleration was highest along the steepest sections of the range such that the frequency of landslide occurrence was strongly correlated to slope gradient. Both vertical and horizontal coseismic displacement demonstrated a strong control over landslide initiation. This result suggests that strike-slip systems experience very different landslide patterning to thrust faults during earthquakes. Based on interferometric analysis of synthetic aperture radar images, the earthquake resulted in a total uplifted volume of 41.6 × 106 m3 and a loss of 95.2 × 106 m3 due to subsidence. This suggests a net tectonic volumetric flux of − 53.6 × 106 m3. Sediment mobilisation by coseismic landslides is estimated at − 2.7 × 106 m3 derived from a manually mapped inventory using SPOT 5 multispectral imagery. Thus, the net volume loss through coseismic subsidence of the mountain range generated a strongly negative mass flux, which was only marginally enhanced by mass wasting

Seismically-induced mass movements and volumetric fluxes resulting from the 2010 Mw=7.2 earthquake in the Sierra Cucapah, Mexico

The observation that sediment flux from mountain ranges struck by high magnitude earthquakes can be strongly influenced by coseismic mass movements brings into question the nature of coseismic deformation as a net contributor to mountain building. To better constrain the role of high-magnitude earthquakes in orogenesis, high-resolution data of earthquake induced mass wasting is required for areas of differing tectonic, morphological, and climatic settings. Here we compare the erosional flux to the tectonic flux associated with the 2010 Mw = 7.2 Sierra El Mayor earthquake in Mexico and examine the landslide patterning of coseismic mass movements associated with this event. The ruptured fault system has a significant strike-slip component with subsidence along the eastern flank and uplift on the western flank of the range. Peak ground acceleration was highest along the steepest sections of the range such that the frequency of landslide occurrence was strongly correlated to slope gradient. Both vertical and horizontal coseismic displacement demonstrated a strong control over landslide initiation. This result suggests that strike-slip systems experience very different landslide patterning to thrust faults during earthquakes. Based on interferometric analysis of synthetic aperture radar images, the earthquake resulted in a total uplifted volume of 41.6 × 106 m3 and a loss of 95.2 × 106 m3 due to subsidence. This suggests a net tectonic volumetric flux of - 53.6 × 106 m3. Sediment mobilisation by coseismic landslides is estimated at - 2.7 × 106 m3 derived from a manually mapped inventory using SPOT 5 multispectral imagery. Thus, the net volume loss through coseismic subsidence of the mountain range generated a strongly negative mass flux, which was only marginally enhanced by mass wasting