We develop a single-station tremor spectrum template detection method that we applied to continuous seismic data recorded by the Mexican National Seismological Service broadband stations. This allows for an unprecedented long-term analysis of tectonic tremor in Mexico over multiple slow slip events (SSEs). We only detect tremor that are within previously discovered tremor regions, thereby extending the catalog in time but not space. The resulting catalog demonstrates the strong correlation of bursts of tremor activity and aseismic slip over multiple slow slip cycles. The M~7 long-term SSEs in the states of Guerrero and Oaxaca are associated with the longest sequences of tremor bursts. Each of these tremor bursts are made up of a series of smaller bursts. In between the large M7 SSEs, there are shorter-duration, isolated tremor bursts. In Guerrero, these shorter bursts were found to accompany M~6 short-term SSEs. The occurrence of these short-duration tremor bursts in Oaxaca demonstrates that small short-term SSEs occur in both major slow slip regions in Mexico. The discrete range of tremor burst sizes and rates suggests that slow slip events in the Mexican subduction zone are organized into characteristic moment and moment rates. The catalog also reveals other aseismic transients, such as postseismic slip in Oaxaca after the 16 February 2018 M w 7.2 Pinotepa Nacional earthquake. We highlight that such long-term catalogs are a useful tool together with geodetic observations to monitor slow slip activity that potentially plays a role in the subduction megathrust cycle.
Se estudian las condiciones de temperatura y la conductividad del hielo del “Glaciar Norte” del volcán Citlaltépetl con el objeto de determinar la existencia de permafrost basal. A partir de registros de temperatura cercanos a la superficie se estimó la temperatura media en estado estacionario del interior del “Glaciar Norte” mediante un método sinusoidal que utiliza las propiedades termo-conductoras del hielo. A través de su perfil de temperatura se obtuvo una aproximación a las condiciones térmicas del principal glaciar de México. Los resultados podrían sugerir la existencia de un permafrost basal, el cual sería producto del aislamiento del hielo y de la conducción térmica por contacto directo entre el hielo y el substrato.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.