Browsing by Author "Montgomery, Jack"
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Item Observed building damage patterns and foundation performance in Mexico City following the 2017 M7.1 Puebla-Mexico City earthquake(2019) Franke, Kevin W.; Candia, Gabriel; Mayoral, J.M.; Wood, Clinton M.; Montgomery, Jack; Hutchinson, Tara; Morales-Velez, Alesandra C.The September 19th, 2017 M7.1 Puebla-Mexico City earthquake introduced strong ground motions into the Mexico City basin, which contains very soft lacustrine soils, dense urban infrastructure, and millions of inhabitants. As a result, 38 mid-rise structures collapsed and several hundred more were damaged. This paper reports the observations related to building performance, damage patterns, and foundation performance made by the two UNAM-GEER engineering reconnaissance teams sent to investigate the geotechnical aspects of the earthquake. The methodology used to perform building damage mapping following the 2017 event is described. Comparisons are made between the observed building damage patterns following the September 19th, 1985 and the 2017 earthquake, and the distinct differences in the damage pattern distribution between the two earthquakes are summarized. Overall, building and foundation performance were observed to be quite good during the 2017 event, especially when compared to the 1985 event. Structures that were observed to be heavily damaged or collapsed were all built prior to 1985, and incorporated poor structural design and/or construction which resonated with the soil column on which they were constructed, and/or were built upon very soft soils that contributed to significant foundation deformations. Detailed building damage pattern maps of specific neighborhoods that were investigated are provided, and lessons learned from this event are summarized.Item The September 19, 2017 Mw 7.1 Puebla-Mexico City Earthquake: Observed Rockfall and Landslide Activity(2019) Candia, Gabriel; Montgomery, Jack; Lemnitzer, Anne; Martínez, AlejandroThis note documents key observations of slope instability and rockfall activity made by the UNAM-GEER reconnaissance team after the Mw 7.1 Puebla-Mexico City earthquake of September 19, 2017. The investigated sites were located in Mexico City and the states of Morelos, Puebla and Mexico. Sites were studied using a combination of ground surveys, UAV imagery, and terrestrial LiDAR imaging. The field reconnaissance efforts were supplemented by analysis of pre- and post-event satellite images to define the boundary of the region affected by earthquake-induced landslides. Most slope failures occurred in remote areas or areas that had a prior history of instability. Overall, the consequences of slope instabilities caused by the 2017 Puebla-Mexico City earthquake were relatively minor compared with the reported structural damage. More than 360 deaths were attributed to this earthquake of which one death was attributed to landslide activities. The size of the area affected by landslides and the intensity of shaking in these areas was consistent with relationships developed in previous studies. The lack of major effects from earthquake-induced landslides is consistent with previous earthquakes in southern Mexico and stands in sharp contrast to many parts of Central America where earthquake-induced landslides pose a significant hazard.