Supplemental Material: Eruption dynamics leading to a volcanic thunderstorm—The January 2020 eruption of Taal volcano, Philippines

Expanded methodology and calculations, plume modeling, and details of lightning data and photographs.<br>

Supplemental Material: Eruption dynamics leading to a volcanic thunderstorm—The January 2020 eruption of Taal volcano, Philippines

Expanded methodology and calculations, plume modeling, and details of lightning data and photographs.<br>

INSAR-BASED LOS SURFACE DEFORMATION COMPARISON OF METRO MANILA BEFORE AND AFTER THE JANUARY 2020 TAAL VOLCANO ERUPTION

The city of Metro Manila has been constantly battered by several hazards on an annual basis. On January 2020, the Taal Volcano erupted with multiple recorded earthquakes. Previous literatures have found that Metro Manila is experiencing a steady subsidence. Determination of land uplift or subsidence is crucial in planning and mitigating the effects of flooding in the area. The study aims to determine whether an uplift occurred in Metro Manila after the eruption or is the study area still experiencing subsidence This study uses a pair L1 SLC Sentinel 1 Images. Radar Interferometry is used to generate Interferograms and Satellite Line of Sight (LOS) deformation was determined between the 2 dates of image acquisition. It was found that the Metro Manila area generally experienced an uplift except for some areas in Caloocan which shows subsidence. The uplift magnitude gradually decreases going from the South to North with a max value of 9.6 cm.

ASHFALL DISPERSAL MAPPING OF THE 2020 TAAL VOLCANO ERUPTION USING DIWATA-2 IMAGERY FOR DISASTER ASSESSMENT

Natural disasters incur many fatalities and economic losses for vulnerable and developing countries such as the Philippines. It is crucial that during calamities, on-ground surveillance is supplemented by low-cost and time-efficient methods such as satellite remote sensing. Diwata-2 is a Philippine microsatellite specifically equipped for disaster assessment. In this study, the capabilities of this satellite in ashfall detection were explored by closely examining the case of the Taal volcano eruption on January 12, 2020. Satellite images covering parts of CALABARZON and Metropolitan Manila before and after the phreatomagmatic eruption were compared. The presence and extent of heavy ash over the study area were identified after the image classification using the Support Vector Machine (SVM) algorithm. A decrease in vegetation cover and built-up areas was also observed. Upon validation, an overall accuracy of 91.4562 and Kappa coefficient of 0.8833 were achieved for the post-eruption ashfall extent map, exhibiting the potential of Diwata-2 imagery in monitoring volcanic eruptions and similar phenomena.

SUPPLEMENTING SATELLITE IMAGERY WITH SOCIAL MEDIA DATA FOR REMOTE RECONNAISSANCE: A CASE STUDY OF THE 2020 TAAL VOLCANO ERUPTION

Social sensing and satellite imagery are named as the top emerging data sources for disaster management. There is a wealth of data, both in quantity and quality that can be extracted from social media platforms such as Twitter, given that the content published by users is generally in real-time and includes a geotag or toponym. To reduce costs, risks, and time, performing reconnaissance using remote sources of information is highly suggested. This study explores how social media data can be used to supplement satellite imagery in post-disaster remote reconnaissance using the January 2020 Taal Volcano Eruption in the Philippines. Tweets about the volcanic eruption were scraped, and ashfall-affected locations mentioned in tweet content were extracted using Named Entity Recognition (NER). To visualize the progression of the tweeted locations, dot density maps and hotspot maps were generated. Additionally, a potential ashfall extent map was generated from processed DIWATA-2 satellite imagery using Support Vector Machine (SVM) classification. An intersection of both dot density map and ashfall extent map was performed for comparative analysis of both data. Validation was carried out by matching the ashfall-affected locations with ground reports from local government offices and news reports. The use of social media data complements satellite image classification in the detection of disaster damage for a quick and cost-efficient remote reconnaissance. This information can be utilized by rescue teams for faster emergency response and relief operations during and after a disaster.

Hazardous base surges of Taal’s 2020 eruption

After 43 years of repose, Taal Volcano erupted on 12 January 2020 forming hazardous base surges. Using field, remote sensing (i.e. UAV and LiDAR), and numerical methods, we gathered primary data to generate well-constrained observed information on dune bedform characteristics, impact dynamic pressures and velocities of base surges. This is to advance our knowledge on this type of hazard to understand and evaluate its consequences and risks. The dilute and wet surges traveled at 50-60 ms−1 near the crater rim and decelerated before making impact on coastal communities with dynamic pressures of at least 1.7 kPa. The base surges killed more than a thousand livestock in the southeast of Taal Volcano Island, and then traveled another ~ 600 m offshore. This work is a rare document of a complete, fresh, and practically undisturbed base surge deposit, important in the study of dune deposits formed by volcanic and other processes on Earth and other planets.

Hazardous Base Surges of Taal’s 2020 Eruption

After 43 years of repose, Taal Volcano erupted on 12 January 2020 forming hazardous base surges. Using field, remote sensing (i.e. UAV and LiDAR), and numerical methods, we gathered primary data to generate well-constrained empirical information on dune bedform characteristics, impact dynamic pressures and velocities of base surges to advance our knowledge on this hazard to understand and evaluate its consequences and risks. The base surges traveled at 50-60 km/hr near the crater and decelerated before making impact on coastal communities with dynamic pressures of at least 1.7-2.1 kPa. The base surges killed more than a thousand livestock in the southeast of Taal Volcano Island, and then traveled another 600 meters offshore. This work is a rare document of a complete, fresh and practically undisturbed base surge deposit, important in the study of dune deposits formed by volcanic, and other processes on Earth and other planets.