De Orizaba Research Articles

Zonación de peligros por procesos gravitacionalesen el flanco suroccidental del volcán Pico de Orizaba, México

The study area is the river Chiquito-Barranca del Muerto watershed that covers 111km2and lies on the southwestern flank of Pico de Orizaba volcano. The water-shed was studied by using aerial photographs of different years and fieldwork with an adaptation of the Landslide Hazard Zonation Protocol of the Washington State Department of Natural Resources, usa. 571 gravitational processes of six types were recognized: shallow, debrisavalanche and deep, debris flows and erthflows, and rock falls. We defined 12 major landforms on which gravitational processes occur: inner gorges, headwalls, active scarps of deep-seated landslides, meanders, plains, three types of hillslopes classified by its gradient: low, moderate, and high, rockfall slopes, non-rule-identified inner gorges, non-rule-identified headwalls, and non-rule-identified converging hillslopes. The potential gravitational processes were classified into three hazard ranges: low, high, and very high. Gravitational processes occur primarily in moderate gradient hillslopes, non-rule-identified inner gorges, inner gorges, and low-gradient hillslopes. The stability is low for plains and low gradient hillslopes, high for moderate and steep gradient hillslopes, and very high for the remaining eight landforms.

Landslide susceptibility of volcanic landforms in the Río El Estado watershed, Pico de Orizaba volcano, Mexico

The combination of high-quality landslide inventories and geomorphic attributes that can be derived and analyzed by geographic information systems can provide powerful and straightforward input into mapping landscape-wide landslide susceptibility. A methodology for generating landslide susceptibility maps can assist land managers in reducing risk to populations and economic land use from landslide hazards, particularly in areas prone to landslide disasters, such as tropical mountain ranges. Pico de Orizaba is the highest stratovolcano in Mexico, and throughout its geologic history, it has had large landslides triggered by flank collapse as well as small landslides triggered by high seasonal rainfall on terrains covered by poorly consolidated materials. The present work analyzes the distribution of small landslides embedded in volcanic landforms to characterize slope instability. The Rio El Estado watershed on the southwestern flank of Pico de Orizaba volcano has been selected as a study area. In the area, landforms are ascertained through aerial photographs, field investigations, and an adaptation of the Landslide Hazard Zonation Protocol of the Washington State Department of Natural Resources, Forest Practices Division in a GIS-based technology. For each landform, a semi-quantitative overall susceptibility rating is derived by using the landslide area rate and the landslide frequency rate. This analysis divides the watershed into seven mass-wasting landforms that are assigned slope stability susceptibility ratings from low to very high. The overall susceptibility rating for this watershed is very high. The technique and its implementation are presented and discussed.

Measuring TeV cosmic rays at the High Altitude Water Cherenkov Observatory

The High-Altitude Water Cherenkov Observatory, or HAWC, is an air shower array designed to observe cosmic rays and gamma rays between 100 GeV and 100 TeV. HAWC, located between the peaks Sierra Negra and Pico de Orizaba in central Mexico, will be completed in the spring of 2015. However, the observatory has been collecting data in a partial configuration since mid-2013. With only part of the final array in data acquisition, HAWC has already accumulated a data set of nearly 100 billion air showers. These events are used to calibrate the detector angular reconstruction using the shadow of the Moon, and to measure the anisotropy in the arrival directions of cosmic rays above 1 TeV. Using data recorded between June 2013 and July 2014, we have observed a significant 10 −4 anisotropy consisting of three statistically significant “hotspots” in the cosmic ray flux. We will discuss these first results from HAWC and compare them to previous measurements of anisotropy in the northern and southern sky.

Effect of climate change on the distribution of Magnolia schiedeana : a threatened species

The effects of climate change on biodiversity are imminent, and these turn out to be particularly alarming for the tropical montane cloud forest. The disappearance of fragments of this forest is expected, along with some of their most characteristic species, such as Magnolia schiedeana . Mexico, through the National System of Protected Natural Areas, must consider protection strategies for those species distributed within the Protected Natural Areas that will be affected by the climate change. This study delimits the distribution of M. schiedeana in Mexico, through ecological niche and future distribution modeling under two periods: years 2040 and 2080. These distribution models tend to move towards northeastern Mexico. The potential distribution of this species declines by 0.36% and 1.94% in the first and second periods, respectively. From this result, the future role of National System of Protected Natural Areas in the long-term conservation of M. schiedeana was analyzed, prompting a proposal to focus conservation efforts on the following Protected Natural Areas: (1) At the federal level: Biosphere Reserve Sierra Gorda and Cañón de Metztitlán, Cuenca del Río Necaxa and El Potosí, National Park El Chico, Cofre de Perote, Pico de Orizaba and Los Mármoles, and Nevado de Toluca. (2) At the state level: Cerro de las Culebras, Cerro de la Galaxia, Cerro de Macuiltepetl, El Tejar Garnica, Francisco Javier Clavijero, La Martinica, Molino de San Roque, Pacho Nuevo and Predio Barragán.

Rediscovery of the pocket gopherOrthogeomys lanius(Rodentia: Geomyidae) in Veracruz, Mexico

The pocket gopher Orthogeomys lanius (Elliot, 1905), unknown to science since the first 2 specimens were captured in 1904, is rediscovered in the mountains south and east of Pico de Orizaba in Veracruz, Mexico. Mitochondrial DNA extracted from the skin of the 109-year-old paratype specimen is nearly identical (0.3% cytochrome-b divergence) to that extracted from 2 newly captured specimens. Phylogenetic analyses of the complete cytochrome-b gene and 2 nuclear genes show O. lanius to be sister to the geographically widespread species O. hispidus. O. lanius has a diploid number of 44 and a fundamental number of 84, and the species is easily distinguished from O. hispidus by its larger size and dense, woolly pelage. Our observations suggest that O. lanius is reasonably abundant in a roughly 1,000-km2 region of central Veracruz, where it persists in forested refugia often too steep and rugged for cultivation by humans.

Mapping landforms for landslide hazards assessment on the SW flank of Pico de Orizaba volcano, Puebla-Veracruz, Mexico

Mapping landforms for landslide hazards assessment on the SW flank of Pico de Orizaba volcano, Puebla-Veracruz, Mexico

Archaic settlement in El Tebernal, Veracruz: First insights into paleoenvironmental conditions and resource exploitation

We present first results about an Archaic (9000–4000 BP) site, El Tebernal, in the eastern part of Mexico. At El Tebernal, a set of lithic artifacts was found associated with a paleosol (lower paleosol) and buried by an upper paleosol and a modern soil. The artifacts are made from local limestone and chert. Selected paleosol properties were evaluated (total organic carbon, grain size distribution, carbon stable isotope composition, magnetic susceptibility, and micromorphology) that provide information about paleoenvironmental conditions. The lower paleosol is composed of the following horizons: 3E, 3EB, 3BE, 3Btg1, 3Btg2, 3C while the upper paleosol only has a 2A horizon. The lower paleosol is very well developed, with in situ clay coatings, moderate weathering of primary minerals, and a matrix free of carbonates, although the alluvium in the lowermost part of the profile contains a mixture of limestone and volcanic materials. The entire sequence is covered by the modern soil mantle which is formed by an A horizon. Radiocarbon ages determined on soil organic matter from the 3Btg1 and 2A horizons were 5580 to 5320 Cal BP and 2350 to 2320 Cal BP, respectively. We interpret the age of 3Btg1 as close to the final stage of soil formation, because the organic matter content in this horizon is illuviated. Pedogenesis likely began sometime prior to the reported age in the Early Holocene. The paleosol properties indicate a long period of landscape stability (n × 103–104 years) under humid and temperate conditions. It is probable that volcanic events from Pico de Orizaba, located several kilometers from El Tebernal, affected this stability. One of the last eruptions produced a block-and-ash flow of dacitic composition dated at 4100 BP that contributed to the end of pedogenesis. The upper paleosol (2A horizon) as well as the modern soil contain ceramics from the Post-classic period (AD 900–1521). The profile is cut by a channel and infilled by a dark material that dates to 1140 to 970 Cal BP (AD 810–980). In consequence, the area has been strongly affected by human occupations during the Holocene. We suggest these ceramic societies caused erosion and activation of geomorphic processes.

A lesson in defining “extinct”

Toni Feder’s Issues and Events news item about the High-Altitude Water Cherenkov Gamma-Ray Observatory under construction in Mexico ( Physics Today, October 2013, page 22) begins by describing the site as “nestled at 4100 m on the slopes of Sierra Negra, an extinct volcano.” However, as the picture accompanying her piece or a cursory examination in Google Earth makes clear, the site is not on the slopes of Sierra Negra. It sits in the saddle between Sierra Negra and its much larger companion Pico de Orizaba, also known as Citlaltepetl. Sierra Negra, a minor flank cone of that larger volcanic system, may now be extinct, but Pico de Orizaba (http://www.volcano.si.edu/volcano.cfm?vnum=1401-10=) absolutely is not. It is dormant at best, having erupted as recently as 1846. To compound the issue, the photograph shows that the observatory site is built squarely in front of an obviously young lava flow. Now, I’m sure that site selection was done with due attention to natural hazards, but as long as astronomers insist on building expensive observatories on top of volcanoes, there needs to be clear understanding and common vocabulary between astronomers and geologists. “Extinct” is a troublesome word when applied to a volcano.

A GIS method for landslide inventory and susceptibility mapping in the Río El Estado watershed, Pico de Orizaba volcano, México

In volcanic terrains, dormant stratovolcanoes are very common and can trigger landslides and debris flows continually along stream systems, thereby affecting human settlements and economic activities. It is important to assess their potential impact and damage through the use of landslide inventory maps and landslide models. In Mexico, numerous geographic information systems (GIS)-based applications have been used to represent and assess slope stability. However, there is no practical and standardized landslide mapping methodology under a GIS. This work provides an overview of the ongoing research project from the Institute of Geography at the National Autonomous University of Mexico that seeks to conduct a multi-temporal landslide inventory and produce a landslide susceptibility map by using GIS. The Rio El Estado watershed on the southwestern flank of Pico de Orizaba volcano, the highest mountain in Mexico, is selected as a study area. The geologic and geomorphologic factors in combination with high seasonal precipitation, high degree of weathering, and steep slopes predispose the study area to landslides. The method encompasses two main levels of analysis to assess landslide susceptibility. First, the project aims to derive a landslide inventory map from a representative sample of landslides using aerial orthophotographs and field work. Next, the landslide susceptibility is modelled by using multiple logistic regression implemented in a GIS platform. The technique and its implementation of each level in a GISs-based technology is presented and discussed.

Landslide inventory mapping and landslide susceptibility modeling assessment on the SW flank of Pico de Orizaba volcano, Puebla-Veracruz, Mexico

Volcanic regions with stratovolcanoes and monogenetic fields are very common and have the potential to trigger along their stream systems landslides and debris flows that damage human settlements, industrial development, cattle raising, forestry, and agricultural activities. However, a practical and standardized landslide mapping methodology using GIS for landslides that occur continually along the stream systems in volcanic terrains has not been applied in Mexico. As a result, landslide inventory maps and related geo-databases that support the prediction of future slope instability in volcanic terrains are lacking. Also, little work has been done on the systematic comparison of different models to predict landslide susceptibility. In this study, a landslide inventory map is derived from a representative sample of landslides using multi-temporal aerial-photo-interpretation and field investigations. The stability is modeled using LOGISNET (Multiple Logistic Regression, Geographic Information System, and Neural Network) as a tool to compare and contrasts the advantages and limitations of two landslides susceptibility models: Stability Index MAPping (SINMAP) and Multiple Logistic Regression (MLR). Both models are embedded in LOGISNET to predict landslides and facilitate the analysis. The validations of the resulting susceptibility maps were performed by comparing them with the inventory map in a contingency table. This research uses the stream system of the Rio Chiquito-Barranca del Muerto watershed as a case-study area. The study area is located in the SW flank of Pico de Orizaba, Volcano, Veracruz-Puebla.

HAWC: A next-generation all-sky gamma-ray telescope

The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is currently under construction 4100m above sea level on the slope of Pico de Orizaba in Mexico. HAWC is a high-duty cycle, large field-of-view instrument capable of monitoring the gamma-ray sky between roughly 50GeV and 100TeV. The detector will be used to record both steady and transient gamma-ray sources and to provide an unbiased survey of the northern sky with 2π sr daily coverage. Upon completion in 2014, HAWC will comprise 300 large light-tight water tanks arrayed over an area of 20,000m2. Each tank will be instrumented with four photomultipliers to detect particles from extensive air showers produced by gamma rays and cosmic rays. With 15 times the sensitivity of its predecessor experiment Milagro, the HAWC Observatory will enable significant detection of Crab-like fluxes each day at a median energy of 1TeV. We present the scientific case for HAWC and describe its design and sensitivity.

The origin of obsidian in the valley of Maltrata, Veracruz México

Five archaeological sites have been selected for a study of the precedence of obsidian from the Valley of Maltrata, Veracruz, Mexico: Teteles de la Ermita and Barriales de las Besanas (pre-Classic, 1,500 B.P. 100 A.P.), Rincon de Aquila (pre-Classic and Classic, 1,500 B.P.–650 A.P.), Tepeyacatitla (Classic, 100–650 A.P. and Rincon Brujo (post-Classic 900/1,000–1,521 A.P.). For this investigation, 51 artifacts were analyzed by neutron activation analysis. The statistic analysis of the chemical compositions allowed us to identify the places of origin of the obsidian sources: Sierra de Pachuca, Pico de Orizaba, Zaragoza-Oyameles, Otumba and Paredon. Based on these results it can be affirmed that the settlements of the valley of Maltrata actively participated in the interregional trade routes of obsidian from the pre-Classic period to the post-Classic period, and maintained relations with the Olmec, Teotihuacan, Cantona and Mexica cultures, among others.

Human and climate influences on frequent fire in a high‐elevation tropical forest

Summary Surface fire has increasingly been regarded as a critical threat to tropical forests, but much of the research documenting degradation of tropical forests by fire comes from the low‐elevation humid tropics. Fire in high‐elevation tropical forests has received less research attention, but these forests are of high conservation value because they support unique ecosystems, which are often isolated due to their restriction to widely separated peaks. We investigated the frequency and ecological impact of fire on a high‐elevation tropical forest of Pinus hartwegii in Pico de Orizaba National Park in central Mexico. This forest was previously thought to have been degraded by excessive human‐caused fires. We assessed human‐caused changes to the fire regime as well as the impact of climate on fire occurrence, both previously undocumented in this region. We found no increase in fire frequency or evidence of degradation of the forest. We found that the forest was uneven‐aged and contained many large and old trees (maximum age 483 years). In the twentieth century, the forest experienced a frequent surface fire regime, with fires scarring trees in 90 of 100 years. However, most fires were small and asynchronous among sites. Inter‐annual climatic variability was not an influential driver of fire, and El Niño–Southern Oscillation was not significantly related to the occurrence of widespread fire. Synthesis and applications. Our results show that this high‐elevation tropical forest has not been degraded but has existed with frequent fires for at least a century. A trend in the 21st century towards less‐frequent fire could be cause for concern, as a decrease in fire frequency could lead to an increase in tree density and a loss of resilience in the face of climate change and other future disturbance. We recommend that managers take into account historical fire regimes in their local areas: frequent surface fires in the case of Pico de Orizaba. It is important to recognize that although fire can be detrimental in many low‐elevation tropical forests, it is an integral part of this high‐elevation tropical forest ecosystem, and other high‐elevation forests may show similar patterns.

Climatic fluctuations as a significant contributing factor for volcanic collapses. Evidence from Mexico during the Late Pleistocene

Climate oscillations have significantly contributed to the planet's evolution, including volcanic activity. Major glaciations have been considered not only as a triggering mechanism for large magmatic eruptions but also inducing volcano instability. Generally, volcano instability can be inferred from detailed volcanological and structural studies of a volcano and its associated depositional sequence, but the triggering mechanism has been always difficult to infer. In this paper, we present evidence of how climatic variations during the Late Pleistocene could have forced sector collapses of the main Mexican stratovolcanoes and enhanced the mobility of associated massive flows inducing the transformation of debris avalanche into debris flows. In particular, the climatic record based on atmospheric moisture content from robustly dated lake record from Guatemala and a U/Th dated speleothem from New Mexico are used here as indicators of summer and winter precipitation. Depositional sequences associated with Late Pleistocene sector collapses of Volcán de Colima, Nevado de Toluca, Citlaltépetl (Pico de Orizaba) and Cofre de Perote volcanoes are here analyzed. Comparing the timing of the event with the climatic record, a combination of summer and/or winter pluvial conditions could have forced and triggered the failure of already unstable volcanoes, even during glacier advances (as for the Citlaltépetl event). Independent of the main cause of the volcano instability (magmatic or tectonic) it is important to highlight that the climatic factor played an important role in enhancing the volcano instability and promoted the lateral transformation of debris avalanches, which under dry conditions would have affected more limited areas.

Oximetry Fails to Predict Acute Mountain Sickness or Summit Success During a Rapid Ascent to 5640 Meters

The purpose of this study was to determine whether arterial oxygen saturation (Spo(2)) and heart rate (HR), as measured by a finger pulse oximeter on rapid arrival to 4260 m, could be predictive of acute mountain sickness (AMS) or summit success on a climb to 5640 m. Climbers (35.0 ± 10.1 years; 51 men, 5 women) were transported from 2650 m to the Piedra Grande hut at 4260 m on Pico de Orizaba within 2 hours. After a median time of 10 hours at the hut, they climbed toward the summit (5640 m) and returned, with a median trip time of 14 hours. The Lake Louise Self-Assessment Scale (LLSS) for AMS, HR, and Spo(2) were collected on arrival at the hut and repeated immediately before and after the climbers' summit attempts. Average Spo(2) for all participants at 4260 m before their departure for the summit was 84.4% ± 3.7%. Thirty-seven of the 56 participants reached the summit, and 59% of all climbers met the criteria for AMS during the ascent. The Spo(2) was not significantly different between those who experienced AMS and those who did not (P = .82); neither was there a difference in Spo(2) between summiteers and nonsummiteers (P = .44). Climbers' HR just before the summit attempt was not related to AMS but was significantly lower for summiteers vs nonsummiteers (P = .04). The Spo(2) does not appear to be predictive of AMS or summit success during rapid ascents.

Proposal for the geometrical distribution of the air cherenkov detectors for CHARM

In this work we propose the geometrical distribution of the air Cherenkov detectors array (ACD), who will be part of the Cosmic High Altitude Radiation Monitor Observatory (CHARM) located at Pico de Orizaba Volcano at 4300 m.a.s.l.. The proposal is based on a library of events built with photons, protons and iron nuclei as primary particles by montecarlo simulations with energies from 1014 eV to 1017 eV. The goal of this detectors will be to determinate the nature of primary cosmic radiation, through measuring the height at which the secondary particles generated reach his maximum number or Xmax, this quantity is related with the effective cross section and finally with the atomic number A of the primary particles. In addition to this we proposed an energy estimator based on the study of the lateral distribution function of the generated events.

SHIFTING PATTERNS OF OBSIDIAN EXCHANGE IN POSTCLASSIC OAXACA, MEXICO

AbstractIn this paper, we present a diachronic analysis of obsidian procurement patterns during the Postclassic period in the Lower Río Verde region of Oaxaca. The study is based on x-ray fluorescence (XRF) and visual analysis of obsidian artifacts from excavated household contexts at Early Postclassic (a.d.800–1100) Río Viejo and Late Postclassic (a.d.1100–1522) Tututepec (Yucu Dzaa). We report the presence of at least six sources of obsidian imported to the lower Río Verde region in the Early Postclassic, whereas during the fourteenth and fifteenth centuries of the Late Postclassic, the local assemblage was dominated by obsidian from Pico de Orizaba and Pachuca. Changes in obsidian procurement patterns in the lower Río Verde region through time are interpreted in light of sociopolitical change at the local, regional, and macroregional scales. The study represents the most detailed analysis of Postclassic period obsidian exchange yet reported from Oaxaca.

Hábitos alimentarios del Coyote en el Parque Nacional Pico de Orizaba

Resumen We examined the food habits of coyotes (Canis latrans) from the Pico de Orizaba National Park by analyzing 136 scat samples that were collected for 11 months in a 7 km transect. Coyote diet consisted mainly of mammals (48.96%), plants (20.28%), birds (6.76%) and insects (0.68%). Our results indicate that annual coyote diet consisted of 15 prey-species. Their diet is based mainly on the rodent Peromyscus melanotis (25.68%), followed by the tomato plant Lycopersium esculentum (11.48%), and the jack rabbit Lepus callotis (9.46%). In the dry season, P. melanotis was the main prey item (29.16%), followed by L. callotis (8.33%). The most important items in the diet of coyotes in the rainy season were P. melanotis (22.36%) and L. esculentum (14.47%). There was no significant variation in prey consumption between seasons.

Geochemical and isotopic profile of Pico de Orizaba (Citlaltépetl) volcano, Mexico: Insights for magma generation processes

Pico de Orizaba or Citlaltépetl volcano is the easternmost and highest stratovolcano of the subduction-related Mexican Volcanic Belt (MVB) located > 400 km NNE of the Middle America Trench. This active volcano comprises four evolutionary stages, ranging in age from 0.65 Ma to the Holocene, and is surrounded by Quaternary monogenetic scoria cones and maar volcanoes. Magmatic products of the stratocone range from basaltic andesites to rhyolites and the cinder cones erupted basalts and basaltic andesites. All rock compositions form a continuous calc–alkaline suite. Petrogenetic processes involved in magma generation and evolution include fractional crystallization and mid-crustal assimilation. Trace element patterns with elevated Ba/Nb, positive Pb spikes, and Th enrichments indicate contributions from subducted sediment. Low Ba/Th ratios suggest melting of hydrous sediment without significant loss of fluid-mobile elements prior to melting. Sr–Nd isotopic ratios of Pico de Orizaba and cinder cones are nearly chondritic and are located on a mixing curve between Pacific MORB and Paleozoic crust of SE Mexico. However, vertical Nd distributions in an 87Sr/ 86Sr vs. εNd diagram cannot be explained by crustal assimilation and indicate contributions of a sedimentary component with unradiogenic Nd. In contrast to other eastern MVB volcanic centres, Pico de Orizaba magmas are derived almost exclusively from a depleted mantle source. Compared to other MVB stratocones, Pico de Orizaba shows the least radiogenic Nd isotope ratios at nearly identical 87Sr/ 86Sr. Steep trends in a 206Pb/ 204Pb vs. 207Pb/ 204Pb diagram favour the involvement of young, 207Pb-enriched oceanic sediments in magma generation processes of Pico de Orizaba volcano. The Pb isotope data do not support any assimilation of lower crustal Grenvillian basement.

High places: cultural geographies of mountains, ice and science

mountains, polar expanses, volcanic peaks are exciting and special environments. 13 leading international geographers explore different aspects of these environments - disorientation, exploration, native knowledge, polar research. This is the first book to do this.High places - be they mountain peaks or the vast expanses of the polar latitudes - have always captured the human imagination. Inaccessible, extreme, they are commonly invested with awe and reverence, as places of physical challenge, intense experience. Increasingly, they are also treated as unique locations for science.High Places explores the fascinating geographies of these special environments, revealing how senses are challenged, objectivities exposed, cultural assumptions laid bare. Whether walking the summit of Pico de Orizaba, the fourth highest volcano in the northern hemisphere; recounting the tale of the American explorer Charles Wilkes, charged with 'immoral mapping' in Antarctica; or exploring the 200,000 year old Greenland ice core; the international contributors reveal the richness and significance of these unique locations. Embracing Europe, Asia, North and Central America, Antarctica and the Arctic, High Places will interest geographers, historians of science, and those interested in polar/mountain studies, landscape, culture and environment.