Volcano-tectonic control of Merapi's lava dome splitting: The November 2013 fracture observed from high resolution TerraSAR-X data

Walter, Thomas R.; Subandriyo, J.; Kirbani, Sri Brotopuspito; Bathke, H.; Suryanto, Wiwit; Aisyah, Nurnaning; Darmawan, Herlan; Jousset, Philippe; Luehr, Birger-G.; Dahm, Torsten

doi:10.1016/j.tecto.2014.11.007

Cited by 46 publications

(24 citation statements)

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“…Most studies analyse either the reflected amplitude or perform interferometric processing of the signal phase values. Interferometric SAR (InSAR) measures the phase difference between satellite radar acquisitions, but resolving the growth on lava domes remains challenging as the phase images require good correlation between acquisitions (Walter et al, 2015). Thus, most InSAR studies focus on crustal deformation affecting the flanks of dome-growing volcanoes (Salzer et al, 2014;Welch and Schmidt, 2017).…”

Section: Lava Dome Monitoringmentioning

confidence: 99%

“…Thus, most InSAR studies focus on crustal deformation affecting the flanks of dome-growing volcanoes (Salzer et al, 2014;Welch and Schmidt, 2017). Lava dome cooling and subsidence (Salzer et al, 2017) and cracks splitting a lava dome have also been detected (Walter et al, 2015). For monitoring lava domes, the analysis of the SAR amplitude is particularly valuable as it can be used to document and quantify lava dome growth e.g., at Merapi and Sinabung, Indonesia (Pallister et al, 2013c(Pallister et al, , 2018 and Mount Cleveland, Alaska (Wang et al, 2015).…”

Section: Lava Dome Monitoringmentioning

confidence: 99%

“…The satellite has a continuous 11 day return orbit and a 12 h time gap between the chosen ascending and descending acquisitions, resulting in constant temporal data acquisition and providing a good overview of the visible changes at Volcán de Colima and thus its eruptive activity. Due to the rapid changes and temporal decorrelation of the SAR signal at dome building volcanoes (Walter et al, 2015;Wang et al, 2015;Arnold et al, 2017;Chaussard, 2017), we investigate the amplitude information rather than the phase information.…”

Section: High-resolution Satellite Radar Observationsmentioning

confidence: 99%

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Load Stress Controls on Directional Lava Dome Growth at Volcán de Colima, Mexico

et al. 2019

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Section: Lava Dome Monitoringmentioning

confidence: 99%

Section: Lava Dome Monitoringmentioning

confidence: 99%

Section: High-resolution Satellite Radar Observationsmentioning

confidence: 99%

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Load Stress Controls on Directional Lava Dome Growth at Volcán de Colima, Mexico

et al. 2019

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“…We then simulated a hazard scenario of gravity driven avalanches by using Titan2D software. The Titan2D software has been used by previous studies to simulate block-and-ash flows due to lava dome collapses (Widiwijayanti et al, 2007;Charbonnier and Gertisser, 2009;Procter et al, 2009;Charbonnier and Gertisser, 2012;Charbonnier et al, 2013). The input parameters of Titan2D should be defined carefully to reduce uncertainty during simulation and to obtain the most realistic result.…”

Section: Scenario Modeling Of Block-and-ash Flowsmentioning

confidence: 99%

Structural weakening of the Merapi dome identified by drone photogrammetry after the 2010 eruption

Darmawan

Walter

Troll

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. Lava domes are subjected to structural weakening that can lead to gravitational collapse and produce pyroclastic flows that may travel up to several kilometers from a volcano's summit. At Merapi volcano, Indonesia, pyroclastic flows are a major hazard, frequently causing high numbers of casualties. After the Volcanic Explosivity Index 4 eruption in 2010, a new lava dome developed on Merapi volcano and was structurally destabilized by six steam-driven explosions between 2012 and 2014. Previous studies revealed that the explosions produced elongated open fissures and a delineated block in the southern dome sector. Here, we investigated the geomorphology, structures, thermal fingerprint, alteration mapping and hazard potential of the Merapi lava dome by using drone-based geomorphologic data and forward-looking thermal infrared images. The block on the southern dome of Merapi is delineated by a horseshoe-shaped structure with a maximum depth of 8 m and it is located on the unbuttressed southern steep flank. We identify intense thermal, fumarole and hydrothermal alteration activities along this horseshoe-shaped structure. We conjecture that hydrothermal alteration may weaken the horseshoe-shaped structure, which then may develop into a failure plane that can lead to gravitational collapse. To test this instability hypothesis, we calculated the factor of safety and ran a numerical model of block-and-ash flow using Titan2D. Results of the factor of safety analysis confirm that intense rainfall events may reduce the internal friction and thus gradually destabilize the dome. The titan2D model suggests that a hypothetical gravitational collapse of the delineated unstable dome sector may travel southward for up to 4 km. This study highlights the relevance of gradual structural weakening of lava domes, which can influence the development fumaroles and hydrothermal alteration activities of cooling lava domes for years after initial emplacement.

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“…Close-up views enabled by highresolution drone photogrammetry further revealed the presence of a linear feature striking NE-SW dissecting this lava dome but not dissecting the apparently younger rock fall deposits (Figure 7d). The dissection of lava domes by linear features has commonly been observed elsewhere following steam-driven explosions (Darmawan et al, 2018a;Walter et al, 2015).…”

Section: Post-eruptive Observationsmentioning

confidence: 85%

Processes culminating in the 2015 phreatic explosion at Lascar volcano, Chile, monitored by multiparametric data

Gaete¹,

Walter²,

Bredemeyer³

et al. 2019

Preprint

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Abstract. Small steam-driven volcanic explosions are common at volcanoes worldwide but are rarely documented or monitored; therefore, these events still put residents and tourists at risk every year. Steam-driven explosions also occur frequently (once every 2–5 years on average) at Lascar volcano, Chile, where they are often spontaneous and lack any identifiable precursor activity. Here, for the first time at Lascar, we describe the processes culminating in such a sudden volcanic explosion that occurred on October 30, 2015, which was thoroughly monitored by cameras, a seismic network, and gas (SO2 and CO2) and temperature sensors. Prior to the eruption, we retrospectively identified unrest manifesting as a gradual increase in the number of long-period (LP) seismic events in 2014, indicating an augmented level of activity at the volcano. Additionally, SO2 flux and thermal anomalies were detected before the eruption. Then, our weather station reported a precipitation event, followed by changes in the brightness of the permanent volcanic plume and (10 days later) by the sudden volcanic explosion. The multidisciplinary data exhibited short-term variations associated with the explosion, including (1) an abrupt eruption onset that was seismically identified in the 1–10 Hz frequency band, (2) the detection of a 1.7 km high white-grey eruption column in camera images, and (3) a pronounced spike in sulfur dioxide (SO2) emission rates reaching 55 kg sec−1 during the main pulse of the eruption as measured by a mini-DOAS scanner. Continuous CO2 gas and temperature measurements conducted at a fumarole on the southern rim of the Lascar crater revealed a pronounced change in the trend of the relationship between the carbon dioxide (CO2) mixing ratio and the gas outlet temperature; we believe that this change was associated with the prior precipitation event. An increased thermal anomaly inside the active crater observed through Sentinel-2 images and drone overflights performed after the steam-driven explosion revealed the presence of a fracture ~ 50 metres in diameter truncating the dome and located deep inside the active crater, which coincides well with the location of the thermal anomaly. Altogether, these observations lead us to infer that a lava dome was present and subjected to cooling and inhibited degassing. We conjecture that a precipitation event led to the short-term build-up of pressure inside the shallow dome that eventually triggered a vent-clearing phreatic explosion. This study shows the chronology of events culminating in a steam-driven explosion but also demonstrates that phreatic explosions are difficult to forecast, even if the volcano is thoroughly monitored; these findings also emphasize why ascending to the summits of Lascar and similar volcanoes is hazardous, particularly after considerable rainfall.

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Volcano-tectonic control of Merapi's lava dome splitting: The November 2013 fracture observed from high resolution TerraSAR-X data

Cited by 46 publications

References 44 publications

Load Stress Controls on Directional Lava Dome Growth at Volcán de Colima, Mexico

Load Stress Controls on Directional Lava Dome Growth at Volcán de Colima, Mexico

Structural weakening of the Merapi dome identified by drone photogrammetry after the 2010 eruption

Processes culminating in the 2015 phreatic explosion at Lascar volcano, Chile, monitored by multiparametric data

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