Dataset for the publication entitled "Understanding Zinc isotopic signatures in volcanic lakes" submitted to GCA. Dataset available for reviewers, will be made available to everyone when accepted for publication.

Lahars (volcanic mudflows) are frequent occurrences in communities near active Philippine volcanoes due to intense and prolonged rainfall. Mayon Volcano is the most active volcano in the Philippines, ejecting pyroclastic deposits that serve as erodible materials for lahars. Damaging lahars have occurred in the past, with the more recent ones in 2006, 2015, 2019 and 2020 posing impacts such as erosion, burial, and flash flooding in low-lying areas. This paper presents the results of an interdisciplinary case study on lahar impact assessment for a selected pilot community at Mayon Volcano. Lahar hazard modeling, an exposure database, and a Filipinized lahar damage state table were combined to estimate potential lahar impacts to buildings for the study area using a lahar impact assessment software tool called REDAS Quick Lahar Impact Simulation Tool (REDAS-QLIST). The tool can estimate lahar losses such as physical damage, economic loss, and total population affected including age-sex distribution. Being able to accurately quantify impact and damage is one of the added values provided by REDAS-QLIST. The damage and loss estimates produced for our case study area were tested using an actual lahar event scenario from Tropical Cyclone (TC) Kammuri in 2019. Stakeholders, especially from local government units, can utilize the methods and results presented to plan and apply adaptable and sustainable disaster risk reduction programs in their communities. Importantly, the methodology can be used with additional lahar modeling results and exposure data through the REDAS QLIST to assess hazard and loss for other volcanic regions in the Philippines.

We report here an increase in the amount of carbon dioxide in Taal lake during the year preceding the January 2020 eruption. Starting in February 2019, the CO 2 emissions from the lake increased from background value (700 t day − 1 ) to a flux close to 2,400 t day −1 at the time of the eruption. We show that the lake acts as a highly sensitive gasometer where CO 2 (aq) reflects the balance between CO 2 supplied to the lake (by hot springs) and CO 2 lost by diffusion at air‐water interface. The lake waters are extremely enriched in dissolved carbon dioxide with pCO 2 values as high as 0.35 atm (350,000 ppmV) equivalent to a CO 2 (aq) of 9.32 mmol l −1 . The residence time of CO 2 in the lake is around 1 week which allows for fast detection of change in magma degassing and makes carbon dioxide a very promising tool for volcano monitoring.

Kanlaon is a stratovolcano situated in central Negros Island, Philippines. It has a record of 30 eruptions since 1866 ranging from phreatic to phreatomagmatic (VEI = 1-2) events. Geothermal manifestations in Kanlaon Volcano are evidenced by the presence of hot springs, boiling mud pools, and warm rivers with temperatures up to 95 degrees C. It has developed a significant hydrothermal system within the volcanic edifice. Through time, it evolved into two distinct hydrothermal systems independent of each other. A mature hydrothermal system, represented by Pataan thermal area is characterized by neutral Na + K chloride (bicarbonate) fluids and an immature system, represented by Hagdan spring is characterized by the presence of acid-sulfate waters. Representative water samples were collected between 2014 and 2017 to further characterize the two systems. Chemical and sulfur isotopic analyses were performed on thermal waters to classify the samples that are linked to the coexistence of these two hydrothermal systems. Results show that thermal spring's pH ranges between 25 and 8.1 and conductivity ranges between 88 mu S/cm to 3930 mu S/cm. Based on their Cl-SO4-HCO3 relative abundances, the thermal waters are classified as acid sulfate, acid-sulfate chloride, neutral chloride and neutral bicarbonate waters. Temperatures of deep-water hydrothermal reservoirs were calculated using fluid-mineral geothermometers and correlated with available borehole temperatures. The Na-K-Mg geothermometer was used to evaluate equilibrium between water and reservoir rocks. Results show that the samples are not in equilibrium with the minerals in the reservoir. Temperature of equilibrium for the mature hydrothermal system was extrapolated to 270 degrees C based on available borehole temperatures. The linear trend towards the equilibrium temperature in the Na-K-Mg geothermometer can be explained by either groundwater/meteoric dilution. This is consistent with the light sulfur isotopic signatures between delta S-34 = -3.4%. and + 1.2% of the mature hydrothermal system (Mambucal), which imply that the origin of sulfates is linked to surficial oxidation of H2S or dilution and mixing of meteoric water. On the other hand, immature hydrothermal system (Hagdan) shows a significantly higher sulfur isotopic composition (delta S-34 = +82%.), which could either result from the disproportionation of magmatic SO2 or from the hydrolysis of elemental sulfur at high temperature between 100 and 350 degrees C. (C) 2019 Published by Elsevier B.V.

Taal volcano (Luzon Island, Philippines) has last erupted in 1977 but has known some periods of increased activity, characterised by seismic swarms, ground deformation, increased carbon dioxide flux and in some cases temperature anomalies and the opening of fissures. We studied major, trace element and sulphur and strontium isotopic composition of Taal lake waters and hot springs over a period of 25 years to investigate the geochemical evolution of Taal volcano's hydrothermal system and its response to volcanic unrest. Long-term evolution of Main Crater Lake (MCL) composition shows a slow but consistent decrease of acidity, SO4, Mg Fe and Al concentrations and a trend from light to heavy sulphate, consistent with a general decrease of volcanic gases dissolving in the hydrothermal system. Na, K and Cl concentrations remain constant indicating a non-volcanic origin for these elements. Sulphate and strontium isotopic data suggest this neutral chloride-rich component represents input of geothermal water into Taal hydrothermal system. A significant deviation from the long-term baseline can be seen in two samples from 1995. That year, pH dropped from 2.6 to 2.2, F, Si and Fe concentrations increased and Na, K and Cl concentrations decreased. Sulphate was depleted in S-34 and temperature was 4 degrees C above baseline level at the time of sampling We attribute these changes to the shallow intrusion of a degassing magma body during the unrest in 1991-1994. More recent unrest periods have not caused significant changes in the geochemistry of Taal hydrothermal waters and are therefore unlikely to have been triggered by shallow magma intrusion. A more likely cause for these events is thus pressurisation of the hydrothermal reservoir by increasing degassing from a stagnant magma reservoir. Our study indicates that new magmatic intrusions that might lead to the next eruption of Taal volcano are expected to change the geochemistry of MCL in the same way as in 1994-1995, with the most notable effects being changes in temperature, pH, F and Si concentrations. (C) 2018 Elsevier B.V. All rights reserved.

The Bulusan volcano is one of the active volcanoes in the Philippines, and is located in southern Luzon. In 2006 and 2007, 19 and 7 distinct phreatic eruptions of the volcano occurred, respectively. Each discrete event produced tephra that was dispersed by prevailing winds mainly to the west or southwest of the summit vent, blanketing portions of the western Sorsogon Peninsula. Some events were recorded as explosion-type earthquakes. Whenever possible, fallout tephra deposits were mapped and sampled to determine the volume and composition of material produced from each eruptive event. Based on the dispersal maps, the average volume was estimated to be 10(5) m(3). No juvenile magma were detected in ash and lithic samples by petrographic and X-ray fluorescence analysis. Therefore, all analyzed samples were considered products of phreatic eruptions.

Silicic volcanic deposits (>65 wt% SiO2), which occur as domes, lavas and pyroclastic deposits, are relatively abundant in the Macolod Corridor, SW Luzon, Philippines. At Makiling stratovolcano, silicic domes occur along the margins of the volcano and are chemically similar to the silicic lavas that comprise part of the volcano. Pyroclastic flows are associated with the Laguna de Bay Caldera and these are chemically distinct from the domes and lavas at Makiling stratovolcano. As a whole, samples from the Laguna de Bay Caldera contain lower concentrations of MgO and higher concentrations of Fe2O3(t) than the samples from domes and lavas. The Laguna de Bay samples are more enriched in incompatible trace elements. The silicic rocks from the domes, Makiling Volcano and Laguna de Bay Caldera all contain high alkalis and high K2O/Na2O ratios. Melting experiments of primitive basalts and andesites demonstrate that it is difficult to produce high K2O/Na2O silicic magmas by fractional crystallization or partial melting of a low K2O/Na2O source. However, recent melting experiments (Sisson et al., Contrib Mineral Petrol 148:635–661, 2005) demonstrate that extreme fractional crystallization or partial melting of K-rich basalts can produce these silicic magmas. Our model for the generation of the silicic magmas in the Macolod Corridor requires partial melting of mantle-derived, evolved, moderate to K-rich, crystallized calc-alkaline magmas that ponded and crystallized in the mid-crust. Major and trace element variations, along with oxygen isotopes and ages of the deposits, are consistent with this model.