EXPOSURE-STANCE CONCEPT MODEL

The paper presents an exposure-stance concept model with three basic elements: proximity regarded as a measurement of nearness, accessibility which refers to the road stance serviceability that convey the people or goods from place to place by means of a vehicle, and connectivity of uncontrolled activities i.e. road and/or building constructions, nearness (measurement) information to be reached from or to be reached by to transport people and resources regardless if it traverses the danger or hazard zones in the slopes of Mayon Volcano. The challenging work is modelling the level of exposure-stances operationally defined as the accessibility in terms of road stance serviceability, connectivity in terms of road constructed and building footprints’ nearness measurement with danger or hazard zones relative to the risk reality phenomenon information happening in Mayon Volcano. This paper practically highlighted results, specifically on the matrix of levels of exposure-stances contexts that creates knowledge prompted by spatial information (nearness measurements) featuring accessibility, connectivity, proximity, risk reality, danger and hazards zones, and OSM roads and building footprints variables. The study concluded that rejecting roads and building (lines and polygons) mimics the perpetual relocation of exposed residents. Also, closing the proclaimed protected forest areas to any activities will likely nil exposure, thus lowering risk hotspot level of significance. Hence, nulling exposure stance variable if not dispersing exposure featuring roads and buildings within the protected areas, development constraint areas, and permanent and extended danger zones of Mayon Volcano has a practical implication to stabilize and sustain developments at the foot slopes of the volcano.

A petrological and conceptual model of Mayon volcano (Philippines) as an example of an open-vent volcano

Mayon is a basaltic andesitic, open-vent volcano characterized by persistent passive degassing from the summit at 2463 m above sea level. Mid-size (< 0.1 km3) and mildly explosive eruptions and occasional phreatic eruptions have occurred approximately every 10 years for over a hundred years. Mayon’s plumbing system structure, processes, and time scales driving its eruptions are still not well-known, despite being the most active volcano in the Philippines. We investigated the petrology and geochemistry of its crystal-rich lavas (~ 50 vol% phenocrysts) from nine historical eruptions between 1928 and 2009 and propose a conceptual model of the processes and magmatic architecture that led to the eruptions. The whole-rock geochemistry and mineral assemblage (plagioclase + orthopyroxene + clinopyroxene + Fe-Ti oxide ± olivine) of the lavas have remained remarkably homogenous (54 wt% SiO2, ~ 4 wt% MgO) from 1928 to 2009. However, electron microscope images and microprobe analyses of the phenocrysts and the existence of three types of glomerocrysts testify to a range of magmatic processes, including long-term magma residence, magma mixing, crystallization, volatile fluxing, and degassing. Multiple mineral-melt geothermobarometers suggest a relatively thermally buffered system at 1050 ± 25 °C, with several magma residence zones, ranging from close to the surface, through reservoirs at ~ 4–5 km, and as deep as ~ 20 km. Diffusion chronometry on > 200 orthopyroxene crystals reveal magma mixing timescales that range from a few days to about 65 years, but the majority are shorter than the decadal inter-eruptive repose period. This implies that magma intrusion at Mayon has been nearly continuous over the studied time period, with limited crystal recycling from one eruption to the next. The variety of plagioclase textures and zoning patterns reflect fluxing of volatiles from depth to shallower melts through which they eventually reach the atmosphere through an open conduit. The crystal-rich nature of the erupted magmas may have developed during each inter-eruptive period. We propose that Mayon has behaved over almost 100 years as a steady state system, with limited variations in eruption frequency, degassing flux, magma composition, and crystal content that are mainly determined by the amount and composition of deep magma and volatile input in the system. We explore how Mayon volcano’s processes and working model can be related to other open-vent mafic and water-rich systems such as Etna, Stromboli, Villarrica, or Llaima. Finally, our understanding of open-vent, persistently active volcanoes is rooted in historical observations, but volcano behavior can evolve over longer time frames. We speculate that these volcanoes produce specific plagioclase textures that can be used to identify similar volcanic behavior in the geologic record.

Geophilosophical realness of risk: a case study in national housing authority resettlement sites in Albay, Philippines

The geophilosophical realness of risk, as introduced in this study, is composed of the risk hotspot or cold spot information which are stored and sorted in hexagonal bins representing the host environment within the 25-km radius from the crater of the Mayon Volcano. The z scores measured from these hexagonal bins mimic the risk realness or risk reality phenomenon happening in Albay Province, Philippines. The objective of the study is to assess risk reality phenomena that generate risk knowledge originated from applying the seven metatheorems based on the Schoen Golden Triangle and the Fibonacci Golden Ratio. Risk assessment in this study uses the stability site selection criteria and hexagonal binning technique to store, sort, and process risk hotspot and coldspot information. This approach led to the disclosure of risk phenomenon on the 14 out of 25 resettlement sites (host environment) that remained at risk and continuously increasing the risk trend. When people are continuously allowed to occupy risk hotspots areas it hints at ineffective risk governance to neutralize the passively exposed population. This study concluded that the risk reality phenomena assessment opens new avenues for scientifically informed land use, nil exposure, and 0-risk policy in addition to the existing 0-casualty goal to get prepared with the right direction, decision and action to sensitively utilize the stable host environments aligned to improve risk governance.

Surface Temperature Monitoring by Satellite Thermal Infrared Imagery at Mayon Volcano of Philippines, 1988-2019

&lt;p&gt;Mayon Volcano on eastern Luzon Island is the most active volcano in the Philippines. It is named and renowned as the &quot;perfect cone&quot; for the symmetric conical shape and has recorded eruptions over 50 times in the past 500 years. Geographically the volcano is surrounded by the eight cities and municipalities with 1 million inhabitants. Currently, its activity is daily monitored by on-site observations such as seismometers installed on Mayon's slopes, plus, electronic distance meters (EDMs), precise leveling benchmarks, and portable fly spectrometers. Compared to existing direct on-site measurements, satellite remote sensing is currently assuming an essential role in understanding the whole picture of volcanic processes. The vulnerability to volcanic hazards is high for Mayon given that it is located in an area of high population density on Luzon Island. However, the satellite remote sensing method and dataset have not been integrated into Mayon&amp;#8217;s hazard mapping and monitoring system, despite abundant open-access satellite dataset archives. Here, we perform multiscale and multitemporal monitoring based on the analysis of a nineteen-year Land Surface Temperature (LST) time series derived from satellite-retrieved thermal infrared imagery. Both Landsat thermal imagery (with 30-meter spatial resolution) and MODIS (Moderate Resolution Imaging Spectroradiometer) LST products (with 1-kilometer spatial resolution) are used for the analysis. The Ensemble Empirical Mode Decomposition (EEMD) is applied as the decomposition tool to decompose oscillatory components of various timescales within the LST time series. The physical interpretation of decomposed LST components at various periods are explored and compared with Mayon&amp;#8217;s eruption records. Results show that annual-period components of LST tend to lose their regularity following an eruption, and amplitudes of short-period LST components are very responsive to the eruption events. The satellite remote sensing approach provides more insights at larger spatial and temporal scales on this renowned active volcano. This study not only presents the advantages and effectiveness of satellite remote sensing on volcanic monitoring but also provides valuable surface information for exploring the subsurface volcanic structures in Mayon.&lt;/p&gt;

Thermoproteus thermophilus sp. nov., a hyperthermophilic crenarchaeon isolated from solfataric soil

A hyperthermophilic crenarchaeon, designated strain CBA1502T, was isolated from volcanic soil in the Mayon volcano in the Philippines. The 16S rRNA gene sequence of strain CBA1502T was most closely related to that of Thermoproteus uzoniensis DSM 5263T (99.2 % similarity) and Thermoproteus tenax Kra 1T (99.0 %). The organism grew at 75–90 °C and pH 4.0–6.0 and in the presence of 0–0.5 % (w/v) NaCl, with optimal growth at 85 °C and pH 5.0. Strain CBA1502T utilized d-arabinose, beef extract, Casamino acids, formate, fumarate, peptone, pyruvate, trimethylamine and yeast extract as energy substrates, and d-arabinose, formate, pyruvate and yeast extract as carbon sources. Fumarate, sulfate, sulfur and thiosulfate functioned as electron acceptors, but not ferric chloride, nitrate, malate or oxidized glutathione. DNA–DNA hybridization studies showed that there was less than 46.1 % relatedness between strain CBA1502T and other members of the genus Thermoproteus. The DNA G+C content of strain CBA1502T was 62.0 mol%. We conclude that, according to its phylogenetic, phenotypic and genotypic characteristics, strain CBA1502T represents a novel species of the genus Thermoproteus, and propose the name Thermoproteus thermophilus sp. nov., with the type strain CBA1502T ( = ATCC BAA-2416T = JCM 17229T).

Ground Deformation of Mayon Volcano Revealed by GPS Campaign Survey

Determining the location and the amount of volume change of the pressure source beneath a volcano during the eruption preparation stage is an important issue in monitoring the magma accumulation. To do so, we have implemented a GPS campaign survey network around the Mayon volcano and monitored ground deformation since 2005. Rapid grounddeflating deformation was detected accompanied by the 2009 eruption. The Mogi model pressure source was estimated to be 8.5 km deep beneath the summit and the amount of volume change –13 × 106 m3. In magma accumulation preceding the 2009 eruption, ground deformation showed a weak inflationary trend, but it was difficult to evaluate the source parameters definitively. After the 2009 eruption, no deformation has been detected by the Continuous GPS observation network since 2012. Trend of many baselines of continuous and campaign network turned to extension since 2014. Magma may have started accumulating beneath the Mayon volcano.