Caldera Region Research Articles

Pendekatan Arsitek Franky Parulian Simanjuntak pada Pengembangan Simarjarunjung Hound Sky

Lake Toba is one of the five North Sumatra destinations considered to be Indonesian Super Priority Destinations. Information obtained from the Central Statistics Agency (BPS) of Simalungun Regency indicates that the number of visitors to Lake Toba tourism spots within Simalungun Regency increased by 55% in 2023. Most of these visitors come from the Parapat and Bukit Indah Simarjarunjung regions. As a result of the numerous national and international events held on Lake Toba, such as the International Formula 1 Powerboat Championship event (F1 Powerboat), the number of accommodations will increase to 83 in 2022. As a consequence of this, the Simalungun region of Lake Toba generally has a high number of accommodations that are in high demand. To accommodate tourists, the Toba Caldera region calls for establishing resorts and other tourist accommodations. Qualitative research methodologies are utilised in this research method. To ensure that the design that is implemented incorporates the Neo-Vernacular architecture of the Simalungun Batak culture, the development of Simarjarunjung Hound Sky in the Toba Caldera region can be accomplished through the approach of architect Franky Parulian Simanjuntak. This can be accomplished by incorporating elements of local culture into the design and utilising Neo-Vernacular architecture.

Solidified magma reservoir derived from active source seismic experiments in the Aira caldera, southern Kyushu, Japan

The Aira caldera, located in southern Kyushu, Japan, originally formed 100 ka, and its current shape reflects the more recent 30 ka caldera-forming eruptions (hereafter, called the AT eruptions). This study aimed to delineate the detailed two-dimensional (2D) seismic velocity structure of the Aira caldera down to approximately 15 km, by means of the travel-time tomography analysis of the seismic profile across the caldera acquired in 2017 and 2018. A substantial structural difference in thickness in the subsurface low-velocity areas in the Aira caldera between the eastern and western sides, suggest that the Aira caldera comprises at least two calderas, identified as the AT and Wakamiko calderas. The most interesting feature of the caldera structure is the existence of a substantial high-velocity zone (HVZ) with a velocity of more than 6.8 km/s at depths of about 6–11 km beneath the central area of the AT caldera. Because no high ratio of P- to S-wave velocity zones in the depth range were detected from the previous three-dimensional velocity model beneath the AT caldera region, we infer that the HVZ is not an active magma reservoir but comprises a solidified and cool remnant. In addition, a poorly resolved low-velocity zone around 15 km in depth suggests the existence of a deep active magma reservoir. By superimposing the distribution of the known pressure sources derived from the observed ground inflation and the volcanic earthquake distribution onto the 2D velocity model, the magma transportation path in the crust was imaged. This image suggested that the HVZ plays an important role in magma transportation in the upper crust. Moreover, we estimated that the AT magma reservoir in the 30 ka Aira caldera-forming eruptions has the total volume of 490 km3 DRE and is distributed in a depth range of 4–11 km.Graphical

The Potential of Budget Participation and Dalihan Natolu Leadership Style to Improve Community Welfare in the Toba Caldera Tourism Geography Area

Objective: This research analyzes the determinants of budgetary participation's effect on financial performance through Dalihan Natolu's leadership style in 4 districts in the Toba Caldera region and conducts a descriptive economic analysis of social and economic indicators in 7 districts post-Regional Autonomy and Fiscal Decentralization. Analyze village category development using the village development index (IDM) in 7 Toba Caldera districts. Estimating economic development parameters in 7 Toba Caldera districts in North Sumatra. Method: This study uses a quantitative method with descriptive analysis. Descriptive statistical analysis in this study was carried out using frequency distribution analysis and inferential statistical analysis including: evaluation of the assumptions of the structure equation model (SEM), SEM analysis, model fit test and hypothesis testing. The data analysis technique in this study uses Partial Least Square (PLS). PLS is a Structural Equation Modeling (SEM) equation model with an approach based on variance or component-based structural equation modeling. This research was conducted in 4 (four) administrative districts located around the Lake Toba Tourism Area which in their kinship life absolutely adhere to the local wisdom of Dalihan Natolu, namely Toba Regency, Samosir Regency, North Tapanuli Regency, Humbang Hasundutan Regency. Conclusion : This quantitative study's findings Budget Participation Factor also affects Financial Performance moderated by Dahlian Natolu's Leadership Style, as shown by t statistics > t table (3,961 > 2,032). To strengthen this analysis, you can also use the P Value, with the condition p < 0.05, which shows 0.000 < 0.05. In 2019, the Human Development Index in 7 Toba Caldera Region Regencies measured Life Expectancy (UHH), Average Length of Schooling (RLS), and Expenditure Per Capita. In 2019–2020, the Toba Caldera Region's Gross Regional Domestic Product (GRDP) is stable and led by Agriculture, Forestry & Fisheries, Wholesale and Retail Trade, and Industrial Management. Karo Regency has the highest HDI and Humbang Ha Anglean the lowest. The comparative IPD for that year increased in 7 Toba Caldera Region Regencies from 2014 to 2018. Toba Caldera districts' Human Development Index (IPM) increases somewhat with GRDP per capita.

Geotourism as a 16-Geosite Empowerment Strategy—For Tourism Sustainability in Toba Caldera Geopark

The study on empowerment strategies for tourism sustainability was carried out in 16 geosites located in seven regencies. These include Karo, Dairi, Simalungun, Samosir, Toba Samosir, North Tapanuli, and Humbang Hasundutan, in Toba Caldera Region (TCA), North Sumatra Province. The empowerment strategies will enhance local and national tourism development policy directives, boost development geared towards community tourism interests, and achieve GGN directives according to the concepts outlined by UNESCO. This geotourism development has been formulated through a synthesis of various investigations including the analyses of government references, potential tourist attractions, and SWOT. Furthermore, the SWOT analysis showed that a travel plan combining the elements of cultural heritage and geosites is an alternative empowerment for sustainable regional development through geotourism, using Pusuk Bukit as a pilot area. Geosites have been mapped as the basis for Toba Caldera’s development.

PENGARUH DAYA TARIK WISATA, ELECTRONIC WORD OF MOUTH, DAN CITRA DESTINASI WISATA TERHADAP KEPUTUSAN BERKUNJUNG WISATAWAN KE DESA WISATA LUBUK KERTANG, KABUPATEN LANGKAT

Lubuk Kertang Tourism Village is a tourist destination in North Sumatra whose existence is not quite popular compared to other tourist villages in North Sumatra which are in the Toba Caldera Region. For this reason, in-depth analysis is needed in various aspects to increase tourist visits to this village. This research is a quantitative descriptive research that aims to determine the effect of tourist attraction, electronic word of mouth, and the image of a tourist destination on the decision to visit tourists to Lubuk Kertang Tourism Village, Langkat Regency. The sample of this research is 100 people taken by using accidental sampling method. Data related to the 4 tested variants were obtained through questionnaires and analyzed using multiple linear regression analysis. The results of the study show that there is a partial and simultaneous influence of tourist attraction, electronic word of mouth, and the image of a tourist destination on the decision to visit tourists to Lubuk Kertang Tourism Village. Thus improving the quality of these three variables is needed so that tourist visits to Lubuk Kertang can increase.

Millennial-scale coseismic landslide history inferred from topographic and stratigraphic features of a post-caldera cone of Aso Volcano in southwestern Japan

The 2016 Mw 7.0 Kumamoto earthquake triggered numerous landslides of fallout tephra deposits around Aso Volcano in southwestern Japan. Although rainfall-induced landslides have been repeatedly observed on the tephra-mantled slopes of this region, the spatial patterns and frequency of coseismic landslides remain unclear because of the scarce landslide evidence associated with palaeoseismicity. To examine the distribution of landslides induced by the 2016 Kumamoto earthquake and possibly by prior large earthquakes, we conducted geomorphological analyses using airborne light detection and ranging (LiDAR) data, together with geological investigations of tephra deposits in the Takanoobane lava dome (TLD), a post-caldera cone of Aso Volcano. Repeated LiDAR surveys performed before and after the earthquake allowed us to quantify the volume and geometry of five coseismic landslides (K1–K5), as well as three component blocks of the K1 landslide (K1a–c). The surveys also allowed identification of 12 older landslides (O1–O12) fully covered by vegetation. Source areas of recent coseismic landslides ranged from 1050 to 14,920 m2; those of older landslides were estimated to be 1110–15,730 m2. The H/L ratios of the K1 landslide and its component blocks K1a–c ranged from 0.139 to 0.165, despite their volumes ranging from 104 to 105 m3. The K1 landslide occurred on the southwest-facing slope, where older landslides were not recognised before the earthquake. Its slip surface was formed at the base of the 30 ka pumice layer. The largest one of the older landslides (O1) is located on the south-facing slope, adjacent to the K1 landslide. Stratigraphic investigations revealed that most of the tephra sequence, including the 30 ka pumice layer, has already been eroded at the centre of the O1 landslide. Radiocarbon dating further constrained the landslide age to ca. 7.0 ka. Because its topographic and stratigraphic features are similar to the features of the K1 landslide, the O1 landslide may have been triggered by a palaeoearthquake approximately 7000 years ago, which was previously unknown around the Aso caldera region.

Dynamic matching—Revisiting the Carpenter model

The phenomenon of dynamic matching was proposed by Carpenter nearly four decades ago. In this work, we perform detailed dynamical studies of the original model studied by Carpenter. Existence of competing mechanisms that influence the extent of dynamic matching with varying depth of the caldera well, as noted by Carpenter, is confirmed. A phase space dynamical viewpoint is provided for the origin of the competing mechanisms. Our results show that the extent of dynamic matching is significantly influenced by the amount of excess energy above the transition state that controls the entrance into the caldera region. Moreover, we find that dynamic matching can persist for fairly deep caldera wells. Quantum dynamical studies are performed to assess the extent of classical-quantum correspondence in the system and the robustness of the dynamic matching mechanism.

Pumice Raft Detection Using Machine-Learning on Multispectral Satellite Imagery

Most of Earth’s volcanic eruptions occur underwater, and these submarine eruptions can significantly impact large-scale Earth systems (e.g., enhancing local primary production by phytoplankton). However, detecting submarine eruptions is challenging due to their remote locations, short eruption durations, lack of sea surface signature (if eruptions do not breach the surface), and the transient nature of the surface manifestations of an eruption (e.g., floating pumice clasts, hydrothermal fluids). We can utilize global satellite imagery of 10–30 m resolution (e.g., Landsat 8, Sentinel-2) to detect new eruptions; however, the large data volumes make it challenging to systematically analyze satellite imagery globally. In this study, we address these challenges by developing a new semi-automated analysis framework to detect submarine eruptions through supervised classification of satellite images on Google Earth Engine. We train our algorithm using images from rafts produced by the August 2019 eruption of Volcano F in the Tofua Arc and present a case study using our methodology on satellite imagery from the Rabaul caldera region in Papua New Guinea. We potentially find a large number of new unreported pumice rafts (in ∼16% of images from 2017–present). After analysis of the spatial pattern of raft sightings and ancillary geophysical and visual observations, we interpret that these rafts are not the result of a new eruption. Instead, we posit that the observed rafts represent remobilization of pumice clasts from previous historical eruptions. This novel process of raft remobilization may be common at near-shore/partially submarine caldera systems (e.g., Rabaul, Krakatau) and may have significant implications for new submarine eruption detection and volcanic stratigraphy.

Insight into the May 2015 summit inflation event at Kīlauea Volcano, Hawai‘i

We use ground and space geodetic data to study surface deformation at Kīlauea Volcano from January to September 2015. This period includes an episode of heightened activity in April and May 2015 that culminated in a magmatic intrusion beneath the volcano's summit. The data set consists of Global Navigation Satellite System (GNSS), tilt, visual and seismic time series along with 25 descending and 15 ascending acquisitions of the Sentinel-1 satellite. We identify four different stages of surface deformation and volcanic activity, which we attribute to pressure changes and the movement of magma in response to an imbalance between magma supply and withdrawal in the shallow plumbing system, eventually leading to an intrusion beneath the summit area. In particular, we model the deformation as due to pressure changes in two subsurface magma bodies: the Halema‘uma‘u Reservoir (HMMR) and South Caldera Reservoir (SCR). The SCR was best described by an ellipsoidal source at 2.8 (2.65–3.07 at 95% confidence) km depth below the south caldera region. The HMMR was modeled as a point source located just east of Halema‘uma‘u crater at 1.5 (0.95–2.62) km depth. We suggest that a short-term increase in the magma supply rate to the volcano is a potential mechanisms for the intrusion, although other factors, like the filling of available void space or a reduced efficiency of magma transport through the volcano's East Rift Zone, may also play a role.

The influence of a pitchfork bifurcation of the critical points of a symmetric caldera potential energy surface on dynamical matching

Many organic chemical reactions are governed by potential energy surfaces that have a region with the topographical features of a caldera. If the caldera has a symmetry then trajectories transiting the caldera region are observed to exhibit a phenomenon that is referred to as dynamical matching. Dynamical matching is a constraint that restricts the way in which a trajectory can exit the caldera based solely on how it enters the caldera. In this paper we show that bifurcations of the critical points of the caldera potential energy surface can destroy dynamical matching even when the symmetry of the caldera is not affected by the bifurcation.

Analysis of Landslide Prone Areas in Tampahan, Toba Samosir Regency, North Sumatra Province

The topography of the Tampahan area which tends to be steep and dominated by tuff lithology can result in a landslide. The intensity of landslides and the resulting losses can be reduced by the analysis of landslide-prone areas in Tampahan. The administration of the area is located in Toba Samosir Regency, North Sumatra Province which is included in the Toba Caldera Region. Analysis of landslide-prone areas is carried out with five parameters namely slope, land use, morphological elevation, lithology, and rainfall. The data processed in this analysis comes from field data, DEMNas (National Digital Elevation Model), and other spatial data. Classification of each parameter and weighting based on literature is away in the analysis of landslide-prone areas of Tampahan. Then do each parameter overlay to get the value of landslide-prone and distinguished based on the calculation of the landslide class interval. The results are divided into five classes that are prone to landslides, namely classes not prone (1-1,8), rather prone (1,8-2,6), quite prone (2,6-3,4), prone (3,4-4,2), and very prone (4,2-5). Based on the analysis that has been done, some areas are very prone to landslides in the southeast while areas that are not prone to landslides are in the southwest of the study area. Therefore, landslide-prone studies are categorized as high landslides with almost 60% coverage of the study area.

Pelaksanaan Kewenangan Pemerintah Daerah Dalam Penertiban Penambangan Galian C Untuk Melindungi Kawasan Geopark Di Kabupaten Bangli

Before defined as the geopark region mount Batur caldera region is oneof the central mining activity of C in Bangli. Once established as a regionalinternational geopark by UNESCO mining activity of C is a major problem becauseit damages the environment and damaging geology sites that threaten the existenceof the geopark. But the fact that until now mining activity C remains. The issue asfollows: how is law protection for geopark existency in Bangli regency, and how iseffectivity of Bangli government authority implementation in controlling on miningactivity of C entrenchment in geopark area in Bangli regency. The research methodapplied in this thesis is emperical law resesarch because occur gap between dassollen with das sein that is gap between theory and reality. The result shows in order to protect geopark the Bangli government has integrate geopark material intoeducation curricullum in Bangli regency, and set up Batur mount area and aroundas area of geology sanctuary. Controll system on C entrenchment conducted by tostop mining at some mining point, traffic change, and arrested on the businessmanof mining who have not business license of mining.

Seismic and geodetic progression of the 2018 summit caldera collapse of Kīlauea volcano

The 2018 eruption of Kīlauea volcano, Hawai'i, resulted in a major collapse of the summit caldera along with an effusive eruption in the lower East Rift Zone. The caldera collapse comprised 62 highly similar collapse cycles of strong ground deformation and earthquake swarms that ended with a magnitude 5 collapse event and one partial cycle that did not end with a collapse event. We analyzed geodetic and seismic data to better understand how the caldera collapse progressed over 3 months of activity, focusing on the cyclical activity. We identified 3 main phases of collapse: initial ring-fault activation and small explosions (Phase 1), an eastward shift in activity and freeing of the central piston (Phase 2), and a recoupling of the piston to the reservoir followed by relatively steady behavior until the eruption's end (Phase 3). Additionally, we observed geodetic evidence of tangential motion from the localization of the main ring fault (Phase 2) and the formation of a major peripheral ring fault on the eastern side of the collapse caldera during Phase 3. Both geodetic and seismic parameters suggest that the collapse may have had an eastward-component of motion after the ring fault system had formed. The cyclical seismic and geodetic parameters show no obvious signs that the collapse was coming to an end, with the only notable change being a significant increase in the ratio of cyclical displacement to co-collapse displacement observed during the last complete cycle on GNSS stations outside the caldera region.

桜島火山および姶良カルデラ地域における61ka以降のマグマ化学組成の時間変化とマグマ溜りシステムの進化(＜特集＞桜島火山)

桜島火山および姶良カルデラ地域における61ka以降のマグマ化学組成の時間変化とマグマ溜りシステムの進化(＜特集＞桜島火山)

平成28年（2016年）熊本地震によって南阿蘇村周辺域で発生した斜面災害

The Kumamoto earthquake (Mj 7.3) on April 16, 2016 triggered numerous landslides in and around Minamiaso Village, which is located at the western part of Aso caldera, southwestern Japan. The landslides were divided into two types: landslides occurring at steep caldera walls and landslides generated on the slopes of post-caldera central cones of Aso Volcano. Several landslides occurred on slopes steeper than 25° at the northwestern to western caldera walls, which comprise pre-Aso volcanic rocks (lavas and pyroclastics). The largest landslide (ca. 300 m high, 130–200 m wide) occurred on the western caldera wall, damaging National Route 57 and the Hohi line of the Japan Railway. Because a clear rupture surface could not be observed, unstable blocks which had been divided by cracks, were likely to collapse due to the intense earthquake on April 16. At the post-caldera central cones of Aso Volcano, earthquake-induced landslides were generated not only on steep slopes but also on slopes gentler than 10°. They occurred in unconsolidated superficial tephra deposits overlying lavas and agglutinates, and the thickness of the slides usually ranged from 4 to 8 m. The sliding masses traveled long distances (＜600 m), compared to small differences in elevation. The deposits were composed of tephra blocks of a few meters and there was no evidence that they were transported by water. These facts suggest that some landslides mobilized rapidly into debris avalanches, traveling a few hundred meters. The associated debris avalanche resulted in five casualties and severe damage to houses at the foot of the Takanoobane lava dome. The characteristics of the April 16, 2016 earthquake-induced landslides differ from those of rainfall-induced landslides in July 2012, June 2001, and July 1990 at Aso Volcano, and provide important information for preventing or mitigating future landslide disasters in the Aso caldera region.

Annual rates of ground deformation (1993–2010) at Campi Flegrei, Italy, revealed by Persistent Scatterer Pair (PSP) – SAR interferometry

Campi Flegrei is an active volcanic district located along the Eastern Tyrrhenian continental margin, Italy, and is worldwide known for dramatic ground deformation phenomena (bradyseism) recorded over the last centuries. The purpose of this article is to present the annual rates of ground deformation fields (average velocity, average acceleration, and combined annual velocity/acceleration) at Campi Flegrei, during almost two decades (years 1993–2010). The research work was conducted based on a temporal analysis and advanced mapping of Persistent Scatterer Pair (PSP) data, obtained from interferometric processing of radar satellite European Remote Sensing-1/2 and Environmental Satellite (ENVISAT) scenes of the study area. Patterns and trends of annual PSP velocity have provided a reconstruction of the spatial and temporal variability of ground deformation in terms of uplift and/or subsidence along the satellite line of sight (LOS). The analysis of annual PSP velocity and acceleration has revealed an intense dynamics of the Campi Flegrei caldera collapse-resurgence system, testified by the high PSP velocity and acceleration values, as well as the significant changes in the rates of ground deformation through time. The main results of this research indicate that the largest ground deformation is localized within and around the structural border of the Campi Flegrei caldera and suggest a systematic recurrence of opposite trends (uplift vs. subsidence) in the ground deformation of the inner caldera region with respect to the surrounding areas throughout the analysed time period.

The Neapolitan Yellow Tuff caldera offshore the Campi Flegrei: Stratal architecture and kinematic reconstruction during the last 15ky

Abstract In this study we integrate high-resolution swath bathymetry, single channel reflection seismic data and gravity core data, to provide new insights into the shallow structure and latest Quaternary to Holocene evolution of the submerged sector of the Neapolitan Yellow Tuff (NYT) caldera (Campi Flegrei) in the Pozzuoli Bay. The new data allow for a reconstruction of the offshore geometry of the NYT caldera collapse–ring fault system, along with the style and timing of deformation of the inner caldera resurgence. Our interpretation shows that the NYT eruption (~ 15 ka BP) was associated with a caldera collapse bounded by an inward-dipping ring fault system. The ring fault system consists in a 1–2 km wide fault zone that encircles an inner caldera region ~ 5 km in diameter and is often marked by the occurrence of pore fluids ascending through the fault zone, up to the seafloor, particularly in the western sector of the bay. A shallow magmatic intrusion along the ring fault zone was also detected offshore Bagnoli in the eastern part of the Pozzuoli Bay. Following the NYT eruption, the inner caldera region underwent significant deformation and resurgence with a maximum cumulative uplift of the offshore structure in the order of 180 m. The net uplift rate of the caldera resurgent dome was ~ 9–12 mm/year during the period 15.0–6.6 ka BP. The style of deformation of the resurgent structure can be described in terms of a broad doming, accompanied by subordinate brittle deformation, mostly concentrated in a small apical graben at the summit of the resurgent dome. Chronostratigraphic calibration of seismic profiles obtained by three tephra layers cored in the Pozzuoli Bay indicates 5 to 25 m of post-Roman differential subsidence and tilting towards ESE of the inner caldera resurgence, as recorded by the drowning of the infralittoral prograding wedge below the present-day storm wave base.

New constraints on dike injection and fault slip during the 1975–1984 Krafla rift crisis, NE Iceland

Correlation of KH9 spy and SPOT5 satellite images, airphotos, digital elevation model differencing, electronic distance measurement, and leveling survey data is used to constrain the deformation resulting from the 1975–1984 Krafla rifting crisis. We find that diking typically extends to depths of 5 km, while the dike tops range from 0 km in the caldera region to 3 km at the northern end of the rift. Extension is accommodated by diking at depth and normal faulting in the shallowest crust. In the southern section of the Krafla rift, surface opening is 80% of the dike opening at depth. Over the 70–80 km length of the rift, the average dike opening was 4.3–5.4 m. From these estimates, we calculate the total geodetic moment released over the Krafla rift crisis, 4.4–9.0×1019 Nm, which is an order of magnitude higher than the seismic moment released over the same time period, ~5.8×1018 Nm. The total volume of magma added to the upper crust was 1.1–2.1×109m3. This study highlights how optical image correlation using inexpensive declassified spy satellite and airphotos, combined with simple models of crustal deformation, can provide important constraints on the deformation resulting from past earthquake and volcanic events.

The investigation of the geothermal potential at the Silali volcano, Northern Kenya Rift, using electromagnetic data

The Silali volcano is one among a number of volcanoes found along the axis of the Kenya rift system that has experienced immense volcanism and faulting that formed a huge caldera at its summit. In this study, we investigate the resistivity distribution within the Silali volcano region in order to define a magma chamber that was the source of young lava flows covering the region and to better describe the geologic and structural features or faults around this region that may allow fluid movement. The data reveal a magma chamber beneath the caldera and a northeast trending fault west of the volcano in the Kapedo region. Potential fluid circulation zone within the caldera region are also evident. The depth to the magma chamber is estimated from the deeper low resistivity zone to be about 6km from the surface. A low resistivity zone less than 20ohm-m, at 1–2km depth is interpreted to be a low temperature clay (smectite) alteration zone resulting from fluid circulation as heat is transferred to shallower depth. The resistivity then increases abruptly beneath the inferred low temperature alteration zone and this increase in resistivity is interpreted as a change from clay mineralization to a chlorite-dominated system producing the observed decrease in resistivity. The decrease in conductivity may also imply a decrease in permeability due to decreasing connectivity of conductive fluids. The resistivity changes with depth could be temperature dependent and the inferred chlorite zone may suggest a temperature above approximately 240°C. The deeper low resistivity zone is interpreted as molten rocks and can be interpreted to indicate temperatures above 700°C of the magma body at a depth of 6km.

Volcanic stratigraphy and evidence of magma mixing in the Quaternary Payun Matru volcano, andean backarc in western Argentina

The Payun Matru Volcanic Field is located in the Payenia Basaltic Province of the recent back-arc of western Argentina (35°S-38°S). This province is younger than 5 Ma, and most of its volcanic activity took place since 2 Ma. The Payun Matru Volcanic Field contains two composite volcanoes, Payun Matru and Payun Liso, and two basaltic fields in an E-W oriented zone, located east and west of the Payun Matru volcano. Payun Matru is the largest volcano of this volcanic field, and consists of a shield-shaped edifice with a circular summit caldera of 8 km in diameter. The composition of both composite volcanoes is alkaline and predominantly trachytic, having also minor intermediate lavas. The basaltic fields consist of basalts and trachybasalts, with clinopyroxene and abundant olivine as phenocrysts and also in the groundmass. Textures indicating mixing and mingling processes, such as dusty plagioclases along with clear ones, biotite replaced by anhydrous minerals and two groundmasses with a fluid-fluid relationship, are common in the early pre-caldera stage of Payun Matru and some post-caldera lavas. The latest post-caldera lavas are trachytic, with clean sanidine phenocrysts without disequilibrium textures. A remarkable characteristic of the Payun Matru Volcanic Field is the fact that the Payun Matru caldera is surrounded by basaltic fields at its base, while no basalts were erupted in the caldera region. We propose that the absence of basaltic lavas in the Payun Matru volcano is due to the presence of a magmatic chamber below it, and that the mafic magmas rising from deeper levels were unable to erupt without interaction with more evolved melts. Intermediate hybrid magmas produced as a consequence of magma mixing and mingling between basaltic and trachytic magmas, are present in the early and mid-history of Payun Matru volcano. We present here new information about the Quaternary Payun Matru Volcanic Field derived from field work, petrography, and major element geochemistry and 87Sr/86Sr isotopic ratios. For the first time a detailed map of the Payun Matru Volcanic Field and its volcanic stratigraphy, primarily based on field observations, are presented.