TY - JOUR A1 - Melnick, Daniel A1 - Li, Shaoyang A1 - Moreno, Marcos A1 - Cisternas, Marco A1 - Jara-Munoz, Julius A1 - Wesson, Robert A1 - Nelson, Alan A1 - Baez, Juan Carlos A1 - Deng, Zhiguo T1 - Back to full interseismic plate locking decades after the giant 1960 Chile earthquake JF - Nature Communications N2 - Great megathrust earthquakes arise from the sudden release of energy accumulated during centuries of interseismic plate convergence. The moment deficit (energy available for future earthquakes) is commonly inferred by integrating the rate of interseismic plate locking over the time since the previous great earthquake. But accurate integration requires knowledge of how interseismic plate locking changes decades after earthquakes, measurements not available for most great earthquakes. Here we reconstruct the post-earthquake history of plate locking at Guafo Island, above the seismogenic zone of the giant 1960 (M-w = 9.5) Chile earthquake, through forward modeling of land-level changes inferred from aerial imagery (since 1974) and measured by GPS (since 1994). We find that interseismic locking increased to similar to 70% in the decade following the 1960 earthquake and then gradually to 100% by 2005. Our findings illustrate the transient evolution of plate locking in Chile, and suggest a similarly complex evolution elsewhere, with implications for the time- and magnitude-dependent probability of future events. Y1 - 2018 U6 - https://doi.org/10.1038/s41467-018-05989-6 SN - 2041-1723 VL - 9 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Moreno, Marcelo Spegiorin A1 - Melnick, Daniel A1 - Rosenau, M. A1 - Báez, Juan Carlos A1 - Klotz, Jan A1 - Oncken, Onno A1 - Tassara, Andres A1 - Chen, J. A1 - Bataille, Klaus A1 - Bevis, M. A1 - Socquet, Anne A1 - Bolte, John A1 - Vigny, C. A1 - Brooks, B. A1 - Ryder, I. A1 - Grund, Volker A1 - Smalley, B. A1 - Carrizo, Daniel A1 - Bartsch, M. A1 - Hase, H. T1 - Toward understanding tectonic control on the M-w 8.8 2010 Maule Chile earthquake JF - Earth & planetary science letters N2 - The Maule earthquake of 27th February 2010 (M-w = 8.8) affected similar to 500 km of the Nazca-South America plate boundary in south-central Chile producing spectacular crustal deformation. Here, we present a detailed estimate of static coseismic surface offsets as measured by survey and continuous GPS, both in near- and far-field regions. Earthquake slip along the megathrust has been inferred from a Joint inversion of our new data together with published GPS, InSAR, and land-level changes data using Green's functions generated by a spherical finite-element model with realistic subduction zone geometry. The combination of the data sets provided a good resolution, indicating that most of the slip was well resolved. Coseismic slip was concentrated north of the epicenter with up to 16 m of slip, whereas to the south it reached over 10 m within two minor patches. A comparison of coseismic slip with the slip deficit accumulated since the last great earthquake in 1835 suggests that the 2010 event closed a mature seismic gap. Slip deficit distribution shows an apparent local overshoot that highlight cycle-to-cycle variability, which has to be taken into account when anticipating future events from interseismic observations. Rupture propagation was obviously not affected by bathymetric features of the incoming plate. Instead, splay faults in the upper plate seem to have limited rupture propagation in the updip and along-strike directions. Additionally, we found that along-strike gradients in slip are spatially correlated with geometrical inflections of the megathrust. Our study suggests that persistent tectonic features may control strain accumulation and release along subduction megathrusts. KW - GPS KW - Chile KW - Maule KW - slip model KW - FEM Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.01.006 SN - 0012-821X VL - 321 IS - 3 SP - 152 EP - 165 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Moreno, Marcelo Spegiorin A1 - Melnick, Daniel A1 - Rosenau, M. A1 - Bolte, John A1 - Klotz, Jan A1 - Echtler, Helmut Peter A1 - Báez, Juan Carlos A1 - Bataille, Klaus A1 - Chen, J. A1 - Bevis, M. A1 - Hase, H. A1 - Oncken, Onno T1 - Heterogeneous plate locking in the South-Central Chile subduction zone building up the next great earthquake JF - Earth & planetary science letters N2 - We use Global Positioning System (GPS) velocities and kinematic Finite Element models (FE-models) to infer the state of locking between the converging Nazca and South America plates in South-Central Chile (36 degrees S -46 degrees S) and to evaluate its spatial and temporal variability. GPS velocities provide information on earthquake-cycle deformation over the last decade in areas affected by the megathrust events of 1960 (M-w = 9.5) and 2010 (M-w = 8.8). Our data confirm that a change in surface velocity patterns of these two seismotectonic segments can be related to their different stages in the seismic cycle: Accordingly, the northern (2010) segment was in a final stage of interseismic loading whereas the southern (1960) segment is still in a postseismic stage and undergoes a prolonged viscoelastic mantle relaxation. After correcting the signals for mantle relaxation, the residual GPS velocity pattern suggests that the plate interface accumulates slip deficit in a spatially and presumably temporally variable way towards the next great event. Though some similarity exist between locking and 1960 coseismic slip, extrapolating the current, decadal scale slip deficit accumulation towards the similar to 300-yr recurrence times of giant events here does neither yield the slip distribution nor the moment magnitude of the 1960 earthquake. This suggests that either the locking pattern is evolving in time (to reconcile a slip deficit distribution similar to the 1960 earthquake) or that some asperities are not persistent over multiple events. The accumulated moment deficit since 1960 suggests that highly locked patches in the 1960 segment are already capable of producing a M similar to 8 event if triggered to fail by stress transfer from the 2010 event. KW - GPS KW - Chile KW - Maule KW - locking degree KW - postseismic deformation KW - earthquake cycle Y1 - 2011 U6 - https://doi.org/10.1016/j.epsl.2011.03.025 SN - 0012-821X VL - 305 IS - 3-4 SP - 413 EP - 424 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lange, Dietrich A1 - Bedford, J. R. A1 - Moreno, M. A1 - Tilmann, F. A1 - Báez, Juan Carlos A1 - Bevis, M. A1 - Krüger, Frank T1 - Comparison of postseismic afterslip models with aftershock seismicity for three subduction-zone earthquakes: Nias 2005, Maule 2010 and Tohoku 2011 JF - Geophysical journal international N2 - We focus on the relation between seismic and total postseismic afterslip following the Maule M-w 8.8 earthquake on 2010 February 27 in central Chile. First, we calculate the cumulative slip released by aftershock seismicity. We do this by summing up the aftershock regions and slip estimated from scaling relations. Comparing the cumulative seismic slip with afterslip modelswe showthat seismic slip of individual aftershocks exceeds locally the inverted afterslip model from geodetic constraints. As the afterslip model implicitly contains the displacements from the aftershocks, this reflects the tendency of afterslip models to smear out the actual slip pattern. However, it also suggests that locally slip for a number of the larger aftershocks exceeds the aseismic slip in spite of the fact that the total equivalent moment of the afterslip exceeds the cumulative moment of aftershocks by a large factor. This effect, seen weakly for the Maule 2010 and also for the Tohoku 2011 earthquake, can be explained by taking into account the uncertainties of the seismicity and afterslip models. In spite of uncertainties, the hypocentral region of the Nias 2005 earthquake is suggested to release a large fraction of moment almost purely seismically. Therefore, these aftershocks are not driven solely by the afterslip but instead their slip areas have probably been stressed by interseismic loading and the mainshock rupture. In a second step, we divide the megathrust of the Maule 2010 rupture into discrete cells and count the number of aftershocks that occur within 50 km of the centre of each cell as a function of time. We then compare this number to a time-dependent afterslip model by defining the 'afterslip to aftershock ratio' (ASAR) for each cell as the slope of the best fitting line when the afterslip at time t is plotted against aftershock count. Although we find a linear relation between afterslip and aftershocks for most cells, there is significant variability in ASAR in both the downdip and along-strike directions of the megathrust. We compare the spatial distribution of ASAR with the spatial distribution of seismic coupling, coseismic slip and Bouguer gravity anomaly, and in each case we find no significant correlation. KW - Creep and deformation KW - Earthquake dynamics KW - Seismicity and tectonics KW - Continental margins: convergent Y1 - 2014 U6 - https://doi.org/10.1093/gji/ggu292 SN - 0956-540X SN - 1365-246X VL - 199 IS - 2 SP - 784 EP - 799 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Tilmann, F. A1 - Zhang, Y. A1 - Moreno, M. A1 - Saul, J. A1 - Eckelmann, F. A1 - Palo, M. A1 - Deng, Z. A1 - Babeyko, Andrey A1 - Chen, K. A1 - Báez, Juan Carlos A1 - Schurr, B. A1 - Wang, R. A1 - Dahm, Torsten T1 - The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake? JF - Geophysical research letters N2 - On 16 September 2015, the M-W = 8.2 Illapel megathrust earthquake ruptured the Central Chilean margin. Combining inversions of displacement measurements and seismic waveforms with high frequency (HF) teleseismic backprojection, we derive a comprehensive description of the rupture, which also predicts deep ocean tsunami wave heights. We further determine moment tensors and obtain accurate depth estimates for the aftershock sequence. The earthquake nucleated near the coast but then propagated to the north and updip, attaining a peak slip of 5-6 m. In contrast, HF seismic radiation is mostly emitted downdip of the region of intense slip and arrests earlier than the long period rupture, indicating smooth slip along the shallow plate interface in the final phase. A superficially similar earthquake in 1943 with a similar aftershock zone had a much shorter source time function, which matches the duration of HF seismic radiation in the recent event, indicating that the 1943 event lacked the shallow slip. Y1 - 2016 U6 - https://doi.org/10.1002/2015GL066963 SN - 0094-8276 SN - 1944-8007 VL - 43 SP - 574 EP - 583 PB - American Geophysical Union CY - Washington ER -