Seven years of postseismic deformation following the 2003 Mw = 6.8 Zemmouri earthquake (Algeria) from InSAR time series

Abstract

We study the postseismic surface deformation of the Mw 6.8, 2003 Zemmouri earthquake (northern Algeria) using the Multi‐Temporal Small Baseline InSAR technique. InSAR time series obtained from 31 Envisat ASAR images from 2003 to 2010 reveal sub‐cm coastline ground movements between Cap Matifou and Dellys. Two regions display subsidence at a maximum rate of 2 mm/yr in Cap Djenet and 3.5 mm/yr in Boumerdes. These regions correlate well with areas of maximum coseismic uplifts, and their association with two rupture segments. Inverse modeling suggest that subsidence in the areas of high coseismic uplift can be explained by afterslip on shallow sections (<5 km) of the fault above the areas of coseismic slip, in agreement with previous GPS observations. The earthquake impact on soft sediments and the ground water table southwest of the earthquake area, characterizes ground deformation of non‐tectonic origin. The cumulative postseismic moment due to 7 years afterslip is equivalent to an Mw 6.3 earthquake. Therefore, the postseismic deformation and stress buildup has significant implications on the earthquake cycle models and recurrence intervals of large earthquakes in the Algiers area.

Estimates of aseismic slip associated with small earthquakes near San Juan Bautista, CA

“…tens of percent of the coseismic moment [e.g., Donnellan and Lyzenga, 1998;Segall et al, 2000;Hsu et al, 2006;Gahalaut et al, 2008;Johanson and Bürgmann, 2010;Cetin et al, 2012;D'Agostino et al, 2012;Lin et al, 2013;Gonzalez-Ortega et al, 2014]. In Figures 10 and S27, we plot some of the published postseismic moment ratios for comparison with those obtained here.…”

“…As in Figure 7, circles are for stacked groups, and crosses are for individual earthquakes. Squares, diamonds, and triangles plotted for larger earthquakes show the estimated postseismic to coseismic moment ratios estimated by Savage and Svarc [1997], Segall et al [2000], Bürgmann et al [2001], Jacobs et al [2002], Melbourne et al [2002], Miura et al [2004], Hsu et al [2006], Langbein et al [2006], Pritchard and Simons [2006], Subarya et al [2006], Chlieh et al [2007], Freed [2007], Podgorski et al [2007], Ryder et al [2007], Barbot et al [2008], Furuya and Satyabala [2008], Jónsson [2008], Mahsas et al [2008], Amoruso and Crescentini [2009], Murray-Moraleda and Simpson [2009], Cheloni et al [2010], Johanson and Bürgmann [2010], Ryder et al [2010], Bell et al [2012], Cetin et al [2012], D'Agostino et al [2012, Wen et al [2012], Lin et al [2013], Dogan et al [2014], Gonzalez-Ortega et al [2014], Taira et al [2014], Fattahi et al [2015], and Floyd et al [2016].…”

“…Seismogenic zone widths vary, but the widths of earthquakes generally start to exceed the continental seismogenic zone width as their magnitudes exceed 6 or 7. In the published literature, most M ≤ 6 earthquakes have postseismic slip with moment larger than the coseismic moment [Langbein et al, 2006;Freed, 2007;Furuya and Satyabala, 2008;Bell et al, 2012;Fattahi et al, 2015], while most 6 < M ≤ 7 earthquakes do not [e.g., Donnellan and Lyzenga, 1998;Amoruso and Crescentini, 2009;Cheloni et al, 2010;Johanson and Bürgmann, 2010;Cetin et al, 2012;D'Agostino et al, 2012]. However, the large afterslip after 5 < M < 6 earthquakes could be an observational bias.…”

Omori‐like decay of postseismic velocities following continental earthquakes

“…Red line shows the best fitting Omori model and black solid lines show the region where 95% of Omori models plot. Data sources: Barbot et al [], Atzori et al [], Reddy et al [], Calais et al [], Hsu et al [], Perfettini and Avouac [], Gourmelen and Amelung [], Hammond et al [], Hetland and Hager [], Bie et al [], Biggs et al [], Freed et al [], Pollitz [], Lammali et al [], Pollitz et al [], Amoruso et al [], Hao et al []; Nishimura and Thatcher []; Reilinger []; Pollitz and Thatcher []; Reilinger [], Dalla Via [], Ergintav et al [], Diao et al [], Ryder et al [], Deng et al [], D'Agostino et al [], Ryder et al [], Vergnolle [], Copley et al [], Floyd et al [], Ryder et al [], Deng et al [], Jouanne et al [], Barbot et al [], Langbein [], Podgorski et al [], Jónsson [], Copley and Reynolds [], Copley [], Riva et al [], Dogan et al [], Feng et al [], Cetin et al [], and Mahsas et al []…”

Postseismic deformation following theMw7.2, 23 October 2011 Van earthquake (Turkey): Evidence for aseismic fault reactivation

“…The slip distribution on both faults was then inverted for with a negativity constraint on the dip slip component (i.e., no normal slip) using both horizontal and vertical components of GPS displacements (Table S1). To avoid unphysical oscillatory slip, a smoothing operator was applied to the modeled slip distribution [ Çetin et al , ]. We chose a smoothing factor of 0.25 that provides the best compromise between the roughness of slip and misfit to the data for both the Van and Bostaniçi faults (Figure c).…”