Seismicity and tectonics of the Rivera Plate and implications for the 1932 Jalisco, Mexico, earthquake

Abstract

Seismicity on and near the boundaries of the Rivera plate is examined in order to determine the subduction regime of the Rivera plate and its influence on the earthquake behavior of the northernmost section of the mid‐America trench. In particular, we address the question of a Rivera‐Cocos boundary.There have been several large historic earthquakes in the coastal areas of the Mexican states Colima and Jalisco, but the last large event was in June 1932 (the 1932 Jalisco earthquake, Ms = 8.1). The present quiescence has lasted longer than the average recurrence interval for the Mexican subduction zone, and the Jalisco area is now categorized as a seismic gap. However, if subduction in this area is dominated by the motion of the Rivera plate, which is subducting at half the rate of the Cocos plate, the deficiency of earthquake activity may not be unusual. In an attempt to better delineate the Rivera‐Cocos boundary,intermediate‐sized earthquakes along and near the Rivera fracture zone and the mid‐America trench were relocated with the joint epicenter determination method. We found that in general, the catalog locations are fairly accurate, with the average change in epicenter upon relocation being 12 km. Seismicity along the Rivera fracture zone follows the physiographic trend of the fracture zone, but east of its intersection with the East Pacific Rise, seismicity is more diffuse. Two intermediate‐sized earthquakes in this diffuse area have focal mechanisms suggesting that they represent Rivera‐Cocos boundary motion. Reexamination of arrival time data for the 1932 Jalisco earthquake yields an epicenter at 19.57°N, 104.42°W, close to the boundary zone inferred from these two earthquakes. We conclude that the possibility that the 1932 Jalisco earthquake broke the northernmost section of the Cocos‐North American plate interface, as opposed to the Rivera‐North American plate interface, cannot be ruled out.

Relative motions of the Pacific, Rivera, North American, and Cocos plates since 0.78 Ma

“…On the basis of the occurrence of two strike-slip earthquakes just northwest of the Manzanillo trough (Figure 8b), Eissler and McNally [1984] propose that Rivera-Cocos motion is accommodated via left-lateral motion along a north trending fault zone. A recent series of offshore strike-slip earthquakes that were triggered by the October 9, 1995, Manzanillo earthquake strongly supports such a model.…”

Morfotectónica de Jalisco y Oaxaca (1), México

“…Para el estudio se han tenido en consideración, además de los trabajos anteriormente mencionados, los siguientes resultados: Aguirre et al (2005); Allan (1986); Álvarez (2007); Barrientos et al (2006); Barrier et al (1998);Blackwell y Richards (2004); Bourgois y Michaud (2004); Campa (1978); Campa y Coney (1983) ;Chulick Mooney (2002); Courboulex et al (1997); Demant (1984); DeMets (2001); DeMets y Traylen (2000); Ego y Anson (2002); Eissler y McNally (1984); Ferrari et al (2012Ferrari et al ( , 1992; Figueroa (1970); García y Suárez (1996); Gutiérrez et al (2015); Guzmán et al (1989); Hubp et al (1985); Instituto Nacional de Estadística, Geografía e Informática (2005A); Kostoglodov y Bandy (1995); Kostoglodov y Pacheco (1999) ;López Ramos (1983); Hubp (1990); Hubp y Ortiz (1980); Manea et al (2005Manea et al ( , 2003Manea et al ( , 2002; Medina (1997); Meschede y Barckhausen (2000); Moore y Buffington (1968); Morán (1984); Nieto Samaniego et al (2005Samaniego et al ( , 1995; Nixon (1982); Núñez Cornú et al (2016); Ortiz Pérez y Boceo (1989); O...…”

Using an Enhanced Dataset for Reassessing the Source Region of the 2003 Armería, Mexico Earthquake

“…EISSLER and MCNALLY (1984) and SINGH et al (1985) suggested a dip angle of 20°for the interface between the Rivera and North American Plates. NÚ Ñ EZ-CORNÚ and SÁ NCHEZ-MORA (1999), reported a dip angle of 12°as estimated from local seismicity data, and similar values were obtained from reflection-refraction studies carried out in the central and northern regions of the Jalisco coast (DAÑ OBEITIA et al, 1997).…”

“…More controversial are the geometry of the interface and the relative motion between the Rivera and Cocos Plates. Does the interface lie under the CRZ (NIXON, 1982) or further north (EISSLER and MCNALLY, 1984)? Is it a convergent (DEMETS and STEIN, 1990) or divergent (BANDY, 1992) boundary?…”