Volcanic processes and human exposure as elements to build a risk model for Volcan de Fuego, Guatemala

The activity of Fuego volcano during the 1999 - 2013 eruptive episode is studied through field, remote sensing and observatory records. Mapping of the deposits allows quantifying the erupted volumes and areas affected by the largest eruptions during this period. A wide range of volcanic processes results in a diversity of products and associated deposits, including minor airfall tephra, rockfall avalanches, lava flows, and pyroclastic flows. The activity can be characterized by long term, low level background activity, and sporadic larger explosive eruptions. Although the background activity erupts lava and ash at a low rate (~ 0.1 m3/s), the persistence of such activity over time results in a significant contribution (~ 30%) to the eruption budget during the studied period. Larger eruptions produced the majority of the volume of products during the studied period, mainly during three large events (May 21, 1999, June 29, 2003, and September 13, 2012), mostly in the form of pyroclastic flows. A total volume of ~ 1.4 x 108 m3 was estimated from the mapped deposits and the estimated background eruption rate. Posterior remobilization of pyroclastic flow material by stream erosion in the highly confined Barranca channels leads to lahar generation, either by normal rainfall, or by extreme rainfall events. A reassessment of the types of products and volumes erupted during the decade of 1970\u27s allows comparing the activity happening since 1999 with the older activity, and suggests that many of the eruptive phenomena at Fuego may have similar mechanisms, despite the differences in scale between. The deposits of large pyroclastic flows erupted during the 1970\u27s are remarkably similar in appearance to the deposit of pyroclastic flows from the 1999 - 2013 period, despite their much larger volume; this is also the case for prehistoric eruptions. Radiocarbon dating of pyroclastic flow deposits suggests that Fuego has produced large eruptions many times during the last ~ 2 ka, including larger eruptions during the last 500 years, which has important hazard implications. A survey was conducted among the local residents living near to the volcano, about their expectations of possible future crises. The results show that people are aware of the risk they could face in case of a large eruption, and therefore they are willing to evacuate in such case. However, their decision to evacuate may also be influenced by the conditions in which the evacuation could take place. If the evacuation represents a potential loss of their livelihood or property they will be more hesitant to leave their villages during a large eruption. The prospect of facing hardship conditions during the evacuation and in the shelters may further cause reluctance to evacuate. A short discussion on some of the issues regarding risk assessment and management through an early warning system is presented in the last chapter

Evidence of instability in previously-mapped landslides as measured using GPS, optical, and SAR data between 2007 and 2017: A case study in the Portuguese Bend Landslide Complex, California

Velocity dictates the destructive potential of a landslide. A combination of synthetic aperture radar (SAR), optical, and GPS data were used to maximize spatial and temporal coverage to monitor continuously-moving portions of the Portuguese Bend landslide complex on the Palos Verdes Peninsula in Southern California. Forty SAR images from the COSMO-SkyMed satellite, acquired between 19 July 2012 and 27 September 2014, were processed using Persistent Scatterer Interferometry (PSI). Eight optical images from the WorldView-2 satellite, acquired between 20 February 2011 and 16 February 2016, were processed using the Co-registration of Optically Sensed Images and Correlation (COSI-Corr) technique. Displacement measurements were taken at GPS monuments between September 2007 and May 2017. Incremental and average deformations across the landslide complex were measured using all three techniques. Velocity measured within the landslide complex ranges from slow (\u3e 1.6 m/year) to extremely slow (\u3c 16 mm/year). COSI-Corr and GPS provide detailed coverage of m/year-scale deformation while PSI can measure extremely slow deformation rates (mm/year-scale), which COSI-Corr and GPS cannot do reliably. This case study demonstrates the applicability of SAR, optical, and GPS data synthesis as a complimentary approach to repeat field monitoring and mapping to changes in landslide activity through time

Mapas de amenaza por caída de ceniza y proyectiles balísticos, volcán de Pacaya, Guatemala

La actividad volcánica alrededor del mundo es muy variada y compleja. En Guatemala existen alrededor de 43 estructuras que son consideradas como volcanes y que se alinean de oeste a este del país debido a la zona de subducción. A la actualidad la clasificación de volcanes publicada por INSIVUMEH en el ranking de Peligrosidad Volcánica define tres volcanes con actividad diaria significativa: Pacaya, Fuego y Santiaguito, las cuales generan productos volcánicos que afectan poblaciones, infraestructuras, medios de vida y vías aéreas en todo el país (Roca et al., 2021). Debido a su cercanía con la ciudad de Guatemala y los productos volcánicos que genera, el volcán de Pacaya es uno de los volcanes más peligrosos, catalogado como un volcán con un VEI 3, su actividad varía entre efusiva de tipo estromboliana y explosiva con probabilidades de desarrollar actividad subpliniana como lo menciona Kitamura y Matías (1995)

Eruption frequency patterns through time for the current (1999–2018) activity cycle at Volcán de Fuego derived from remote sensing data:Evidence for an accelerating cycle of explosive paroxysms and potential implications of eruptive activity

Volcán de Fuego is a stratovolcano in Guatemala that has produced over 50 VEI ≥ 2 eruptions since 1524. After two decades of quiescence, in 1999 Fuego entered a new period of eruptive activity that continues until the present day, characterized by persistent Strombolian activity interspersed with occasional “paroxysmal” eruptions of greater magnitude, the most recent of which occurred in 2018. The land surrounding Fuego accommodates tens of thousands of people, so greater understanding of its eruptive behaviour has important implications for hazard assessment. Nevertheless, there is relatively little literature that studies recent (since 1999) activity of Fuego in detail. Using time-series analysis of remote sensing thermal data during the period 2000–2018 combined with recent bulletin reports, we present evidence for a new eruptive regime beginning in 2015. We find that this regime is defined by a greater frequency of paroxysmal eruptions than in previous years and is characterized by the following sequence of events: (i) effusion of lava flows and increase in summit explosive activity, followed by (ii) an intense eruptive phase lasting 24–48 h, producing a sustained eruptive column, continuous explosions, and occasional pyroclastic flows, followed by (iii) decrease in explosive activity. We discuss various models that explain this increase in paroxysmal frequency, and consider its implications for hazard assessment at Fuego. We advocate the pairing of remote sensing data with monitoring reports for understanding long-term changes in behaviour of poorly-instrumented volcanoes. The results that we present here provide a standard for informed assessment of future episodes of unrest and paroxysmal eruptions of Fuego

The geoscientist as international community development practitioner: On the importance of looking and listening

© 2016 The Geological Society of America. All rights reserved. Many geoscientists apply their expertise to international community development through projects that involve direct interaction with host country agencies, community groups, and individuals. As someone with expertise or fi nancial resources, one often has power to frame the defi nition of success around one\u27s own perceived reality regarding human development. Both local counterparts and international geoscientists themselves are often in a position to shape project goals toward their own needs and interests, rather than those of intended benefi ciaries. We argue that one-sided engagement is often ineffective and even harmful for target benefi ciaries. Awareness of such power dynamics minimizes the waste of resources and unintentional perpetuation of harmful social dynamics. Guidelines are presented in this editorial to help geoscientists partner equitably with groups or communities they intend to serve. The guidelines in this editorial may assist geoscientists to identify the felt needs of their target benefi ciaries, defi ne their own role in meeting those needs, defi ne project goals of mutual interest, and make progress toward meeting felt needs. These guidelines include: (1) form relationships and build trust; (2) understand the local context; (3) be observant of internal power relations; (4) examine your motivations and expertise; (5) utilize local expertise in project implementation; and (6) recognize change takes time and investment in monitoring and evaluation. Although equitable engagement is rarely straightforward, especially in an unfamiliar cultural or socioeconomic context, it is crucial if geoscientists are to contribute effectively to global development

Actualización de mapas de amenaza por flujos de lava del volcán de Pacaya, San Vicente Pacaya, utilizando modelos de procesos físicos y validación de campo

Guatemala es un país con una gran diversidad geológica, al sur del país se encuentra la zona de subducción lo que origina una cadena volcánica. En la actualidad se reconocen 25 volcanes activos de los cuales 3 poseen actividad constante y largos periodos eruptivos. Los volcanes Santiaguito, Fuego y Pacaya debido a la actividad que poseen han sido monitorizados y estudiados por varios años, esto nos permite entender tanto los procesos eruptivos, como amenazas potenciales de cada uno de estos. El volcán de Pacaya ha presentado largos periodos eruptivos que corresponden a una actividad efusiva y a explosiones estrombolianas desde 1961. Los flujos de lava alcanzan diferentes longitudes y salen a la superficie en diferentes puntos, algunos cercanos al cono Mackenney. La introducción de nuevas técnicas de mapeo geológico y la implementación de simulaciones para determinar zonas que pueden estar expuestas a amenazas volcánicas, son de gran aporte para el desarrollo de las comunidades que se encuentran ubicadas en los alrededores de los volcanes, los mapas de amenazas volcánicas, son de gran utilidad para el ordenamiento territorial. El objetivo principal de esta investigación es actualizar los mapas de amenaza volcánica por flujos de lava del volcán de Pacaya

Geoscience technical cooperation to enhance the volcano monitoring capacity at Pacaya volcano, Guatemala

© 2015 SEG. Volcanic risk management and monitoring background The risk to human life and properties due to volcanic activity is very high in some regions of the world. Such is the case of Pacaya volcano, located in Guatemala, which has produced a series of damaging and in some cases fatal eruptions, since prehistoric times, documented in the known historical record, beginning in the 16th century, and particularly well known for the last 50 years (Kitamura and Matias, 1995; Rose et al., 2013; Matias et al. 2012). The global database of volcanic incidents compiled by Witham (2005) shows Pacaya amongst the volcanoes with most recurrent events of this type worldwide during the 20th century. Recently a series of eruptions have caused fatalities and extensive damage to the local and national economy, including the May 2010 eruption (Wardman, 2012), prompting the Guatemalan government authorities and people in the affected communities to focus their efforts in reducing the risk from such eruptions. Funded by the Society of Exploration Geophysicists, through the NGO Geologists Without Border, we are pursuing a project to enhance the volcano monitoring capacity of the local volcano observatory, at the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH) in charge of forecasting the activity at Pacaya volcano, in collaboration with the San Carlos University (USAC) and the Pacaya Volcano National Park authority (PVNP)

Evidence of Instability in Previously-Mapped Landslides as Measured Using GPS, Optical, and SAR Data between 2007 and 2017: A Case Study in the Portuguese Bend Landslide Complex, California

Velocity dictates the destructive potential of a landslide. A combination of synthetic aperture radar (SAR), optical, and GPS data were used to maximize spatial and temporal coverage to monitor continuously-moving portions of the Portuguese Bend landslide complex on the Palos Verdes Peninsula in Southern California. Forty SAR images from the COSMO-SkyMed satellite, acquired between 19 July 2012 and 27 September 2014, were processed using Persistent Scatterer Interferometry (PSI). Eight optical images from the WorldView-2 satellite, acquired between 20 February 2011 and 16 February 2016, were processed using the Co-registration of Optically Sensed Images and Correlation (COSI-Corr) technique. Displacement measurements were taken at GPS monuments between September 2007 and May 2017. Incremental and average deformations across the landslide complex were measured using all three techniques. Velocity measured within the landslide complex ranges from slow (> 1.6 m/year) to extremely slow (< 16 mm/year). COSI-Corr and GPS provide detailed coverage of m/year-scale deformation while PSI can measure extremely slow deformation rates (mm/year-scale), which COSI-Corr and GPS cannot do reliably. This case study demonstrates the applicability of SAR, optical, and GPS data synthesis as a complimentary approach to repeat field monitoring and mapping to changes in landslide activity through time