Title: Relating the long-term and short-term vertical deformation across a transect of the forearc in the central Mexican subduction zone Author: María Teresa Ramírez-Herrera, Krzysztof Gaidzik, Steven Forman, Vladimir Kostoglodov, Roland Bürgmann, Christopher W. Johnson Citation style: Ramírez-Herrera María Teresa, Gaidzik Krzysztof, Forman Steven, Kostoglodov Vladimir, Bürgmann Roland, Johnson Christopher W. (2018). Relating the long-term and short-term vertical deformation across a transect of the forearc in the central Mexican subduction zone. “Geosphere” (Vol. 14, iss. 2 (2018), s. 419-439), doi 10.1130/GES01446.1 Research Paper THEMED ISSUE: Subduction Top to Bottom 2 GEOSPHERE Relating the long-term and short-term vertical deformation across GEOSPHERE; v. 14, no. 2 a transect of the forearc in the central Mexican subduction zone doi:10.1130/GES01446.1 María Teresa Ramírez-Herrera1,*, Krzysztof Gaidzik1,*,†, Steven Forman2,*, Vladimir Kostoglodov3,*, Roland Bürgmann4,*, and Christopher W. Johnson4,* 1Laboratorio Universitario de Geofísica Ambiental, Instituto de Geografía, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510 México, DF, México 9 figures; 2 tables; 1 supplemental file 2Department of Geology, Baylor University, Waco, Texas 76798, USA 3Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510 México, DF, México 4Berkeley Seismological Laboratory, Department of Earth and Planetary Science, University of California Berkeley, Berkeley, California 94720, USA CORRESPONDENCE: maria _teresa _ramirez@ yahoo .com, tramirez@ igg .unam .mx, ramirez@ seismo .berkeley .edu ABSTRACT INTRODUCTION CITATION: Ramírez-Herrera, M.T., Gaidzik, K., Earthquake-cycle deformation, which includes earthquake ruptures, inter- Spatial scales of earthquake cycles involving rapid earthquake rupture, Forman, S., Kostoglodov, V., Bürgmann, R., and seismic strain, and transient slow slip events, spans spatial scales ranging inter seismic deformation, and transient slow slip behavior span from fractions Johnson, C.W., 2018, Relating the long-term and short-term vertical deformation across a transect of from fractions of a meter to thousands of kilometers. Similarly, temporal of a meter to thousands of kilometers at plate boundaries. Similarly, tem poral the forearc in the central Mexican subduction zone: scales range from seconds during an earthquake rupture to thousands of years scales range from seconds during an earthquake rupture to thousands of Geosphere, v. 14, no. 2, p. 419–439, doi:10 .1130 of strain accumulation between earthquakes. We discuss results regarding years of strain accumulation between earthquakes. The complexity of tectonic /GES01446.1. the vertical crustal deformation associated with both slow and rapid crustal processes operating over a range of scales and the limited duration of ob- defor mation across a transect of the central Mexican subduction forearc in the servations often focus inquiry onto a limited space-time context that may not Science Editor: Shanaka de Silva Guest Associate Editor: Philippe Agard Guerrero seismic gap, where the Cocos plate underthrusts the North America fully characterize or quantify tectonic variability (e.g., Kostoglodov et al., 2003, plate. This sector of the subduction zone is characterized by a flat-slab geom- 2010; Larson et al., 2004; Franco et al., 2005; Marushima and Ishiyama, 2009; Received 17 October 2016 etry with zones of sharp bending-unbending of the slab, irregularly distrib- Pacheco and Singh, 2010; Walpersdorf et al., 2011). Thus, some of the most Revision received 8 October 2017 uted seismicity, and exceptionally large slow slip events. We used the river important questions concerning subduction zones remain partially addressed, Accepted 27 December 2017 network, topography, geomorphic features, and morphometry on a transect such as: How is tectonic deformation distributed among various modes of fault Published online 26 January 2018 across the forearc to assess Quaternary crustal deformation. The Papagayo slip, particularly for the unique conditions of subduction zones? Also, how spa- drainage network shows that the forearc has been uplifted since the late tially and temporally variable are megathrust slip patterns, and what processes Ceno zoic (~25 Ma), and that rates of uplift increased since the beginning of the and properties control variability? How do processes at depth and in the near Holocene. Uplift is not homogeneous but shows a trend of increase away from surface vary? Lastly, what is the long-term expression of earthquake-cycle the coast. This vertical deformation is strongly influenced by subduction pro- deformation processes observed in the geology and geomorphology of the cesses. Thus, the Papagayo River network is strongly controlled by Holocene subduction forearc? earthquake cycle processes. This is particularly true for the southern section Vertical deformation of the forearc during coseismic, postseismic, and inter- of the drainage basin, where E-W–striking left-lateral strike-slip faults with a seismic stages of the earthquake cycle has been measured in several subduc- OLD G vertical component offset the course of the main river. These faults are accom- tion zones along the Pacific rim, such as the Japan subduction zone (Aoki and modating part of the oblique plate convergence at the Mexican subduction Scholz, 2003; Ozawa et al., 2011; Wang et al., 2012), New Zealand (Beavan et al., zone. We measured the height of a series of terraces and dated quartz extracts 2007, 2010), Indonesia (Sieh et al., 1999; Sieh and Natawidjaja, 2000; Meltzner by optically stimulated luminescence, and we calculated long-term rates of et al., 2006; Chlieh et al., 2007; Prawirodirdjo et al., 2010), Chile (Melnick et al., OPEN ACCESS uplift ranging from 0.5 to 4.9 mm/yr. We discuss associations of forearc topog- 2006, 2012b; Vargas et al., 2011; Wesson et al., 2015), and the Mexican subduc- raphy, faults, and long-term crustal deformation with the Cocos slab geometry, tion zone (Hutton et al., 2001; Azúa et al., 2002; Kostoglodov et al., 2003; Larson distribution of slow slip events, and earthquake-cycle deformation. et al., 2004; Wei et al., 2011). Sense of vertical motion reverses between the stages of deformation (i.e., coseismic, postseismic, and interseismic). How- *E-mail: tramirez@ igg .unam .mx; gaidzik@igg .unam .mx, krzysztof .gaidzik@ us .edu .pl; Steven ever, some areas are more complex, such as the coast of northeastern Japan, _Forman@ baylor .edu; vladi@ servidor .unam .mx; burgmann@ seismo .berkeley .edu; c.w.johnson@ which experienced late-interseismic and coseismic subsidence related to the berkeley .edu This paper is published under the terms of the †Now at Department of Fundamental Geology, Faculty of Earth Sciences, University of Silesia, A.D. 2011 Tohoku earthquake (Japan) although associated landforms indi- CC-BY-NC license. Bedzinska 60, 41-200 Sosnowiec, Poland cated long-term (103 to 106 yr) uplift (Sagiya, 2015; Hashima and Sato, 2017). © 2018 The Authors Downloaded from https://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/14/2/419/4110408/419.pdf by UniwersytetGEOSPHERE Slaski user | Volume 14 | Number 2 Ramírez-Herrera et al. | Long-term and short-term vertical deformation: Central Mexican subduction forearc on 29 October 2018 419 Research Paper Vertical deformation also varies spatially across and along the forearc. The transect of the Mexican subduction zone forearc, in the Guerrero gap, and along A.D. 2004 Sumatra-Andaman earthquake (Indonesia) produced regions both a profile of the Papagayo River. In turn, the height was measured of a vertical of uplift and of subsidence depending on distance from the trench (Meltzner sequence of terraces, and optically stimulated luminescence (OSL) ages were et al., 2006; Prawirodirdjo et al., 2010). Similarly, the 2011 Tohoku earthquake obtained from quartz extracted from fluvial sediments, to estimate long-term produced vertical coseismic and postseismic displacements across the forearc rates of vertical deformation. The association amongst topography, faults, flu- varying in magnitude and with either subsidence or uplift (Ozawa et al., 2011). vial terraces, and river morphology is discussed and related to characteristics of These examples show how the vertical motions of the coasts can differ from the Cocos slab geometry, earthquake cycle deformation, and SSEs. the classical elastic model for stress accumulation and release in the upper plate, and they raise questions regarding (1) the pattern of net deformation that is accumulated through time over several seismic cycles, and (2) the driv- CENTRAL MEXICAN SUBDUCTION ZONE AND GUERRERO ing mechanisms. We attempt to bridge the time scales of the earthquake cycle SEISMIC GAP and vertical deformation by examining the geodetic record (101 yr) and the geologic record (≥103 yr) of vertical deformation of the overriding plate, and Geodynamic Setting and Seismic Activity related earthquake events. Our goal is to understand the fundamental mech- anism for uplift of the forearc inland through different time periods and to The study area is in the forearc of the Cocos–North America subduction analyze individual geodetic results. zone, within the Guerrero seismic gap, a ~200 km segment between 99.2° and Here, to address how surficial and deep processes shape the forearc, we 101.2° W (Fig. 1). No large thrust earthquakes have occurred in the northwest- analyze topography and fluvial terraces