Trench-parallel ridge subduction controls upper-plate structure and shallow megathrust seismogenesis along the Jalisco-Colima margin, Mexico

The parameters allowing for near-trench megathrust ruptures are debated and commonly involve the presence of site-dependent tectonic factors (e.g. rough subducting topography, amount of sediments), implying the need for direct geophysical observations. Here we use seismic imaging techniques to explore the mechanisms triggering shallow ruptures in the Rivera subduction zone, along the non-accretionary Jalisco-Colima continental margin, W Mexico, where three large (Mw~8) tsunamigenic megathrust earthquakes occurred in the last century. The seismic image reveals large interplate topographic variations morphologically alike to incoming trench-parallel ridges seaward of the study area. Ridge subduction only occurs along the southern non-accretionary margin of the Rivera system, where past earthquakes released large near-trench coseismic energy, indicating that subducting ridges enhance interplate coupling. Subducting ridges uplift the margin, causing upper-plate fracturing and low rigidity areas. Such elastic structure quantitatively explains the dynamics of slow and tsunamigenic ruptures in the past. We conclude that ridge subduction beneath the Jalisco-Colima continental margin promotes shallow seismogenesis and explains the large tsunamigenic potential of the area

Technological and infrastructure collaborative seismic research in Western Mexico

In February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, a region with a high occurrence of large earthquakes (> Mw = 7.5) and tsunami generation, on board the British Royal Research Ship James Cook. This successful joint cruise, named TSUJAL, was made possible thanks to a cooperative agreement between NERC and CSIC as part of the Ocean Facilities Exchange Group (OFEG), a major forum of European oceanographic institutions for the exchange of ship time, equipment and personnel. A dense geophysical data set was acquired using for the first time 6 km length seismic streamer facilities from Spain’s Consejo Superior de Investigaciones Cientificas (CSIC), usually operating in the Spanish RV Sarmiento de Gamboa, onboard the British RRS James Cook by solving all mechanical, electrical and electronic problems. The RRS James Cook in turn provides the seismic source and the acoustic, hullmounted echosounder operated by the British Natural Environment Research Council (NERC). Multiscale seismic and echosounder images unravel the subduction geometry, nature of the crust, and evidence faults and mass wasting processes. The data are crucial to estimating fault seismic parameters, and these parameters are critical to carrying out seismic hazard in Mexico, especially when considering largemagnitude earthquakes (Mw 8.0), and to constrain tsunami models.Peer Reviewe

Research on atmospheric volcanic emissions: An overview

The project Research on Atmospheric Volcanic Emissions is a unique effort by NASA and university scientists to investigate the detailed chemical nature of plumes from volcanic eruptions. The major goals of the project are to: 1) understand the impact major eruptions will have on atmospheric chemistry processes, 2) understand the importance of volcanic emissions in the atmospheric geochemical cycles of selected species, 3) use knowledge of the plume chemical composition to diagnose and predict magmatic processes. Project RAVE\u27S first mission used the NASA Lockheed Orion P-3 outfitted with equipment to measure concentrations of the gases SO2, OCS, H2S, CS2, NO, O3and trace elements in particles in Mt. St. Helens\u27 plume on September 22, 1980. Measurements of SO2 column densities in the plume permitted calculations of SO2 fluxes. This article is an overview of the first experimental design factors and performance of the initial RAVE experiment

IC‐P2‐074: Differentiating amnestic MCI converting to probable AD from stable amnestic MCI using FDG‐PET and an AD‐related hypometabolism overlap index

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152594/1/alzjjalz200805067.pd

Multichannel Seismic Imaging of the Rivera Plate Subduction at the Seismogenic Jalisco Block Area (Western Mexican Margin)

During the TSUJAL marine geophysical survey, conducted in February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, considered one of the most active seismic zones in America. This work aims to characterize the internal structure of the subduction zone of the Rivera plate beneath the North American plate in the offshore part of the Jalisco Block, to link the geodynamic and the recent tectonic deformation occurring there with the possible generation of tsunamis and earthquakes. For this purpose, it has been carried out acquisition, processing and geological interpretation of a multichannel seismic reflection profile running perpendicular to the margin. Crustal images show an oceanic domain, dominated by subduction–accretion along the lower slope of the margin with a subparallel sediment thickness of up to 1.6 s two-way travel time (approx. 2 km) in the Middle American Trench. Further, from these data the region appears to be prone to giant earthquake production. The top of the oceanic crust (intraplate reflector) is very well imaged. It is almost continuous along the profile with a gentle dip (<10°); however, it is disrupted by normal faulting resulting from the bending of the plate during subduction. The continental crust presents a well-developed accretionary prism consisting of highly deformed sediments with prominent slumping towards the trench that may be the result of past tsunamis. Also, a bottom simulating reflector (BSR) is identified in the first half a second (twtt) of the section. High amplitude reflections at around 7–8 s twtt clearly image a discontinuous Moho, defining a very gentle dipping subduction plane.Consejo Nacional de Ciencia y Tecnología (México)Ministerio de Economia y Competitividad (España)Universidad Nacional Autonoma de MexicoGeneralitat de CatalunyaDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu

Crustal Architecture at the Collision Zone Between Rivera and North American Plates at the Jalisco Block: Tsujal Project

Processing and analysis of new multichannel seismic records, coincident with wide-angle seismic profiles, acquired in the framework of the TsuJal project allow us to investigate in detail the complex structure of the oceanic domain in the collision zone between Rivera Plate and Block Jalisco at its northern termination. The subducting Rivera Plate, which is overridden by the North American Plate–Jalisco Block, is clearly identified up to 21.5°N (just south of Maria Magdalena Island) as a two clear reflections that we interpret as the interplate and Moho discontinuities. North of the Tres Marias Islands the seismic images display a different tectonic scenario with structures that are consistent with large faulting and rifted margin. A two-dimensional velocity approach for the crustal geometry is achieved using joint refraction/reflection travel time tomography, the uncertainty of the results is assessed by means of Monte Carlo analysis. Our results show an average oceanic crustal thickness of 6–7 km with a moderate increase towards the Jalisco Block, an anomalous thick layers (~3.0 km) displaying a relatively low velocity (~5.5 km/s) underneath Maria Magdalena Rise, and an estimated Moho depth deeper than 15 km in the collision zone between Rivera Plate and Jalisco Block. We have also determined an anomalous crust on the western flank of the Tres Marias Islands, which may be related to the initial phases of continental breakup of the Baja California Peninsula and Mexico mainland. High-resolution bathymetry provides remarkable images of intensive slope instabilities marked by relatively large slides scars of more than 40 km2 extent, and mass-wasting deposits probably triggered by the intense seismicity in the area.Consejo Nacional de Ciencia y Tecnología (CONACYT) –FOMIXJalGobierno de EspañaGobierno del Estado de JaliscoUniversidad Nacional Autonoma de MexicoAgencia Estatal de Investigación (España)Programa Ramón y CajalDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu

P2‐037: Categorical and correlational analyses of baseline fluorodeoxyglucose positron emission tomography images from the Alzheimer’s disease neuroimaging initiative

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152628/1/alzjjalz2008051118.pd

Subsoil classification and geotechnical zonation for Guadalajara City, México: Vs30, soil fundamental periods, 3D structure and profiles

Guadalajara, Jalisco, is the second largest city in Mexico with around 4.5 million inhabitants. A high seismic hazard exists in the city due to forces produced by the interaction between the Rivera, Cocos and North American plates and the smaller Jalisco Block. Guadalajara is one of the largest cities built over pumice soil deposits. Furthermore, the near‐surface phreatic level causes a high susceptibility to liquefaction. All these features can cause extreme earthquake site effects. Due to the fragile inner structure of pumice sands, traditional geotechnical tests are inappropriate to characterize the seismic response. Therefore, we propose the use of surface wave analysis methods (multichannel analysis of surface waves and refraction microtremor), which we applied in 33 sites to define the soil classification in terms of VS30 (the average shear wave velocity between the surface and 30 m depth), the bedrock depth and the fundamental period. From the soil classification, we construct a microzonation map consisting of four geotechnical zones, which we superimpose on the known construction systems within the city. The comparison between the construction period of the buildings and the fundamental frequencies of the soil indicates a high vulnerability to resonance in 1‐ to 4‐storied old buildings constructed of adobe and unreinforced masonry within zones II and III, followed by a medium vulnerability to seismic resonance in compact buildings of 1–4 stories within zone I and 1–12 stories within zones II and IV.TU Berlin, Open-Access-Mittel – 202

P2‐037: Categorical and correlational analyses of baseline fluorodeoxyglucose positron emission tomography images from the Alzheimer’s disease neuroimaging initiative

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152628/1/alzjjalz2008051118.pd

P2‐037: Categorical and correlational analyses of baseline fluorodeoxyglucose positron emission tomography images from the Alzheimer’s disease neuroimaging initiative

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152628/1/alzjjalz2008051118.pd