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We present the first study of seismicity in the region of the Jalisco Block using data recorded by the Jalisco Seismic Accelerometric Telemetric Network between June and December 2015. During this period, 683 local earthquakes with magnitudes between 1.0

Nuñez-Cornu, Francisco ... et al.-- 14 pages, 9 figures, 1 table, In the spring of 2014, an onshore–offshore geophysical experiment (“Crustal Characterization of the Rivera plate–Jalisco Block Boundary and Its Implications for Seismic and Tsunami Hazard Assessment”) was carried out in the frame of the TsuJal project to define the crustal architecture of the western Mexican active margin and identify potential structural sources that can trigger earthquakes and tsunamis at the convergence between the Rivera plate (RP) and the Jalisco Block (JB) within the North American plate. In this work, we present the preliminary results about bathymetric, structural geology, and wide‐angle seismic data of the southern coast of Bahía de Banderas. These data indicate the slab thickness in this area is about 10 km and presents a dip angle of about 8°. Continental crustal thickness below Puerto Vallarta is about 20 km, but no evidences of continental Moho and clear subduction features (trench, accretionary prism) are observed. Nevertheless, this model supports the hypothesis that the region of Bahía de Banderas is under strong crustal stresses generating structural lineaments with the same trends offshore and inland due to the convergence of the RP against the JB. Most of the seismicity reported can be associated with the main structural lineaments. Moreover, the Banderas Canyon (BC) is apparently in an eastward opening process, which seems to continue through the Rio Pitillal river valley; no seismic or morphological evidences were found to suggest the BC is a continuation of the Vallarta graben. Offshore, the Sierra de Cleofas, located south of María Cleofas Island, marks the limit between the RP and the JB along 100 km. It may be the result of the RP pushing against the JB establishing the beginning of the current subduction process, with associated seismic activity. If a subduction type earthquake occurs in this area, the associated magnitude will be about 7.5 and could have a tsunamigenic effect, This Research is funded by Consejo Nacional de Ciencia y Tecnología (CONACYT) – Fondo Mixto CONACYT – Gobierno de Jalisco (FOMIXJAL) 2008-96567 (2009); CONACYT–FOMIXJAL 2008-96539 (2009); CONA-CYT–FOMIXJAL 2010-149245 (2011); CONACYT–FOMIXJAL (2012-08-189963) (MEXICO); Ciencias de la Tierra y Cambio Global (CGL; 2011-29474-C02-01) Dirección General de Investigación (DGI) Plan Nacional I+D+i (España). National Oceanography Centre (NOC) Cruise JC098, RRS James Cook (United Kingdom); Funding for the EL PUMA campaign was provided by Universidad Nacional Autónoma de México (UNAM) (Comisión Académica de los Buques Oceanográficos de la UNAM [CABO]) and Dirección General de Asuntos del Personal Académico de la UNAM (DGAPA) Grant Number IN115513-3; Secretaría de Marina (Mexico) ARM Holzinger; Secretaría de Defensa Nacional (Mexico); Unidad Municipal de Proteccion Civil y Bomberos (Puerto Vallarta, Mexico); Unidad Estatal de Proteccion Civil y Bomberos (Nayarit State, Mexico); Unidad Municipal de Proteccion Civil y Bomberos (Jalisco State, Mexico); Reserva de la Biosfera (Islas Marías) Comisión Nacional de Áreas Naturales y Protegidas (CONANP)-Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT); Órgano Desconcentrado de Prevención y Readaptacion Social de la Secretaría de Gobernación (SEGOB); Secretaría de Relaciones Exteriores (Mexico)

From 1990 to 2004, four cycles of dome growth and explosive dome destruction occurred at the Colima volcano. In this paper, we describe these cycles, focusing on the seismic characteristics of the last three cycles from 1997 and 2004, for which we have the best data. Four episodes of dome building occurred: from early 1991 to late 1992, from November 1998 into January 1999, from November 2001 through February 2003, and from September 2004 into 2005. The rate of extrusion during these episodes ranged from a low-extrusion rate accompanied by seismicity and evolved with time to a high rate of aseismic extrusion for the last episode in 2004. The first of these four extrusive episodes was followed by dome-destroying explosions in July 1994. The second extrusive episode was followed by four dome-destroying explosions over six months and a fifth explosion 17 months later, while the third extrusive episode was followed by three dome-destroying explosions over two months. A fourth extrusive episode began in 2004. The nature of each explosion was somewhat different. For each of the explosions, we compare the total seismic energy released (1) during the hours prior to each explosion, (2) during each explosion, and (3) during the hours after each explosion. We also propose an additional method for classifying the explosions based on coupled acoustic waves and describe characteristics of the volcanic earthquakes recorded. We use data from the 10 May 1999 explosion to construct a new P -wave velocity model for the upper structure of the volcano.