Fluid-triggered earthquake swarms in the Rwenzori region, East African Rift—Evidence for rift initiation

Lindenfeld, Michael; Rümpker, Georg; Link, Klemens; Koehn, Daniel; Batte, Arthur

doi:10.1016/j.tecto.2012.07.010

Cited by 65 publications

(58 citation statements)

References 64 publications

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“…The Rwenzori Mountains are bounded by the Albertine rift on the west and the Lake George rift on the east (Lindenfeld et al 2012a). The southward propagation of the Lake Albert rift and the northward propagation of the Lake George rift lead to the clockwise rotation of the horst with complex intersecting faults in the NE of the Rwenzori Mountains (Koehn et al 2010).…”

Section: Geology and Tectonicsmentioning

confidence: 99%

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The Rwenzori Mountains, a landslide-prone region?

et al. 2015

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The Rwenzori Mountains, a landslide-prone region?Abstract With its exceptionally steep topography, wet climate, and active faulting, landslides can be expected to occur in the Rwenzori Mountains. Whether or not this region is prone to landsliding and more generally whether global landslide inventories and hazard assessments are accurate in data-poor regions such as the East African highlands are thus far unclear. In order to address these questions, a first landslide inventory based on archive information is built for the Rwenzori Mountains. In total, 48 landslide and flash flood events, or combinations of these, are found. They caused 56 fatalities and considerable damage to road infrastructure, buildings, and cropland, and rendered over 14,000 persons homeless. These numbers indicate that the Rwenzori Mountains are landslide-prone and that the impact of these events is significant. Although not based on field investigations but on archive data from media reports and laymen accounts, our approach provides a useful complement to global inventories overlooking this region and increases our understanding of the phenomenon in the Rwenzori Mountains. Considering the severe impacts of landslides, the population growth and related anthropogenic interventions, and the likelihood of more intense rainfall conditions, there is an urgent need to invest in research on disaster risk reduction strategies in this region and other similar highland areas of Africa.

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Section: Geology and Tectonicsmentioning

confidence: 99%

“…This effect can last up to several years after an earthquake event (Chang et al 2007). (Maasha 1975;Lindenfeld et al 2012a). Therefore, it is expected that earthquake activity does influence the spatial and temporal distribution of landslides.…”

Section: Seismic Activitymentioning

confidence: 99%

The Rwenzori Mountains, a landslide-prone region?

et al. 2015

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“…Godano et al (2013) demonstrated the presence of multiple earthquake clusters in research on an Italian swarm, while Lindenfeld et al (2012) recorded several similar clusters in a restricted area while researching fluidtriggered earthquake swarms in the East African Rift. However, while cluster analyses traditionally tended to be density-based, incorporating just spatial coordinates, Zaliapin et al (2008) introduced a statistical method which defined a unified distance between earthquakes in the timespace-energy domain ); this approach was subsequently shown to be robust and effective via research in Southern California Ben-Zion 2011, 2013a, b).…”

Section: Cluster Analysismentioning

confidence: 99%

Rushan earthquake swarm in eastern China and its indications of fluid-triggered rupture

Zheng

et al. 2017

Earthq Sci

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An extraordinary earthquake swarm occurred at Rushan on the Jiaodong Peninsula from October 1, 2013, onwards, and more than 12,000 aftershocks had been detected by December 31, 2015. All the activities of the whole swarm were recorded at the nearest station, RSH, which is located about 12 km from the epicenter. We examine the statistical characteristics of the Rushan swarm in this paper using RSH station data to assess the arrival time difference, t S À P , of Pg and Sg phases. A temporary network comprising 18 seismometers was set up on May 6, 2014, within the area of the epicenter; based on the data from this network and use of the double difference method, we determine precise hypocenter locations. As the distribution of relocated sources reveals migration of seismic activity, we applied the mean-shift cluster method to perform clustering analysis on relocated catalogs. The results of this study show that there were at least 16 clusters of seismic activities between May 6, 2014, and June 30, 2014, and that each was characterized by a hypocenter spreading process. We estimated the hydraulic diffusivity, D, of each cluster using envelope curve fitting; the results show that D values range between 1.2 and 3.5 m 2 /d and that approximate values for clusters on the edge of the source area are lower than those within the central area. We utilize an epidemic-type aftershock sequence (ETAS) model to separate external triggered events from self-excited aftershocks within the Rushan swarm. The estimated parameters for this model suggest that a = 1.156, equivalent to sequences induced by fluid-injection, and that the forcing rate (l) implies just 0.15 events per day. These estimates indicate that around 3% of the events within the swarm were externally triggered. The fact that variation in l is synchronous with swarm activity implies that pulses in fluid pressure likely drove this series of earthquakes.

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“…Melt percolation from an asthenosphere thermal anomaly would facilitate faulting and creeping on inherited structures of the Precambrian lower crust leading to deep seismic swarm observed in Manyara Basin (20-40 km, Albaric et al 2014) and Magadi-Natron basin (15-30 km, Lee et al 2016). Deep earthquakes can be triggered by fluids movement and gas release from melilitite magmas in the lower crust (CO 2 as free phase between 1 and 0.5 GPa; Keir et al 2009;Lee et al 2016;Lindenfeld et al 2012).…”

Section: Carbonatite-nephelinite Association In North Tanzanian Divermentioning

confidence: 99%

Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)

Baudouin

Parat

Denis

et al. 2016

Contrib Mineral Petrol

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International audienceNorth Tanzanian Divergence is the first stage of continental break-up of East African Rift (<6 Ma) and is one of the most concentrated areas of carbonatite magmatism on Earth, with singular Oldoinyo Lengai and Kerimasi volcanoes. Hanang volcano is the southernmost volcano in the North Tanzanian Divergence and the earliest stage of rift initiation. Hanang volcano erupted silica-undersaturated alkaline lavas with zoned clinopyroxene, nepheline, andradite-schorlomite, titanite, apatite, and pyrrhotite. Lavas are low MgO-nephelinite with low Mg# and high silica content (Mg# = 22.4–35.2, SiO2 = 44.2–46.7 wt%, respectively), high incompatible element concentrations (e.g. REE, Ba, Sr) and display Nb–Ta fractionation (Nb/Ta = 36–61). Major elements of whole rock are consistent with magmatic differentiation by fractional crystallization from a parental melt with melilititic composition. Although fractional crystallization occurred at 9–12 km and can be considered as an important process leading to nephelinite magma, the complex zonation of cpx (e.g. abrupt change of Mg#, Nb/Ta, and H2O) and trace element patterns of nephelinites recorded magmatic differentiation involving open system with carbonate–silicate immiscibility and primary melilititic melt replenishment. The low water content of clinopyroxene (3–25 ppm wt. H2O) indicates that at least 0.3 wt% H2O was present at depth during carbonate-rich nephelinite crystallization at 340–640 MPa and 1050–1100 °C. Mg-poor nephelinites from Hanang represent an early stage of the evolution path towards carbonatitic magmatism as observed in Oldoinyo Lengai. Paragenesis and geochemistry of Hanang nephelinites require the presence of CO2-rich melilititic liquid in the southern part of North Tanzanian Divergence and carbonate-rich melt percolations after deep partial melting of CO2-rich oxidized mantle source

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Fluid-triggered earthquake swarms in the Rwenzori region, East African Rift—Evidence for rift initiation

Cited by 65 publications

References 64 publications

The Rwenzori Mountains, a landslide-prone region?

The Rwenzori Mountains, a landslide-prone region?

Rushan earthquake swarm in eastern China and its indications of fluid-triggered rupture

Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)

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