Deformation in Western Guatemala Associated With the NAFCA (North America‐Central American Forearc‐Caribbean) Triple Junction: Neotectonic Strain Localization Into the Guatemala City Graben

Abstract

Recent structural and geodetic data define the Guatemala City graben region as the continental triple junction between the North American plate, Caribbean plate, and the Central American Forearc sliver. We present minor fault analysis, geochronological and geochemical analyses, and newly updated GPS velocities in western Guatemala, west of the Guatemala City graben, to characterize the magnitude and timing of extensional deformation in this poorly understood area. Elongations estimated from fault data are parallel (∼east‐west) and perpendicular to the Polochic‐Motagua fault system to the north, similar to geodetically measured active deformation observed east of the Guatemala City graben. Four new 40Ar/39Ar dates and correlation of tephra deposits suggest that faulting was active during the Pliocene, but ceased eastward toward the Guatemala City graben over time. From west to east, fault cessation occurred before the deposition of the Los Chocoyos ash (75 ka) and E tephra (51 ka). Faulting just west of the Guatemala City graben appears to be active, where a major fault cuts the most recent Amatitlán tephras. Based on this data, we propose a time‐progressive strain model for deformation related to North America‐Caribbean plate interactions, whereby distributed elongation of the westernmost Caribbean plate occurred during the Pliocene but localized mostly within the Guatemala City graben and nearby faults during the Pleistocene. Our model supports that: (a) The Guatemala City graben is effectively the western limit of the Caribbean plate; and (b) Western Guatemala, which was the trailing edge of the Caribbean plate, has been transferred to the forearc region.

Review of Hybrid Methods for the Characterization of Seismic Hazard in Central America

“…6 Ratio R = Distribution of seismicity between background and faults for each magnitude. 7 FtF = Hypothesis of rupture fault to fault. 8 MFD = Magnitude-frequency distribution.…”

“…A summary of the information for each proposed rupture, obtained from previous studies by other authors, is shown below (Table 1). To achieve this goal, information has been compiled, such as slip rates, fault geometry, and kinematics, from previous studies by other authors [3][4][5][6][7][8]. By analyzing this information, four possible rupture scenarios have been generated for the study, two of them in the Motagua fault and others two in the Chixoy-Polochic.…”

Active Triclinic Transtension in a Volcanic Arc: A Case of the El Salvador Fault Zone in Central America

“…The crustal block boundaries are: (1) the Motagua-Polochic Fault Zone, which is the northern boundary of the Caribbean Plate (in contact with the Maya Block); (2) the Hess Escarpment to the south; and (3) the Middle America Trench to the west. The northern end of the CAVA is located at a diffuse triple joint between North American, Caribbean and Cocos Plates [21][22][23]. The northward motion of the forearc sliver (relative to the Caribbean Plate) is accommodated throughout dextral faulting developed along the CAVA.…”

The triple junction of the North America, Cocos, and Caribbean plates. What we know, what we don’t

“…The trace of the transform is lost in western Guatemala (e.g., Plafker, 1976;Guzmán-Speziale et al, 1989) and it is not certain where the transition in the overriding plate along the trench is located (e.g., Guzmán-Speziale and Zúñiga, 2016). This has led several authors (e.g., Plafker, 1976;Sykes et al, 1982;Guzmán-Speziale et al, 1989;Guzmán-Speziale and Meneses-Rocha, 2000;Lyon-Caen et al, 2006;Guzmán-Speziale, 2009;Ratschbacher et al, 2009;Authemayou et al, 2011;Franco et al, 2012;Álvarez-Gómez et al, 2019;Ellis et al, 2019;Graham et al, 2021;Garnier et al, 2022) to propose models for the triple junction. In a broader sense, models for the evolution of the Caribbean plate (e.g., Freeland and Dietz, 1971;Burke, 1988;James, 2009;Benthem et al, 2013;García-Reyes and Dymant, 2021) may also be considered models for the triple junction.…”