The 1905 Chamonix earthquakes: active tectonics in the Mont Blanc and Aiguilles Rouges massifs

Cara, Michel; Woerd, J. van der; Alasset, Pierre-Jean; Benjumea, Juan; Mériaux, Anne-Sophie

doi:10.1007/s00015-017-0262-7

Cited by 9 publications

(11 citation statements)

References 41 publications

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“…Compared to others swarms in the French Alps, the Maurienne swarm is comparable to Vallorcine swarm in the Mont Blanc ECM [Cara et al, 2017] in terms of tectonic and geological position: not far from old hercynian structures and alpine reworked that are clearly visible on the surface in the ECM. The Ubaye swarm [De Barros et al, 2019] affects faults that are inherited but in a higher structural position: in the sediments and nappes covering the ECM eastward of the Penninic frontal thrust.…”

Section: Tectonic and Geological Contextmentioning

confidence: 59%

Unprecedented seismic swarm in the Maurienne valley (2017–2019) observed by the SISmalp Alpine seismic network: operational monitoring and management

Guéguen¹,

Janex²,

Nomade³

et al. 2022

Comptes Rendus. Géoscience

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In 2017-2019, a seismic swarm was triggered in the Maurienne valley (French Alps), with more than 5000 events detected by the regional SISmalp network. The population, who asked SISmalp to provide information on the processes and the associated risk, felt many earthquakes. In a post-L'Aquila trial context, we conducted a reflection on the scientific and social operational management of the crisis. The geological and tectonic analysis, the deployment of a temporary seismic network, an automatic double-difference relocation procedure (HypoDD) after clustering earthquakes, as well as the interactions with the population and the risk managers, have been carried out jointly. The length and unpredictability of the sequence complicated crisis management and the relations between local authorities and civil protection. The involvement of SISmalp, beyond its main scientific and observation prerogatives, has contributed to moderate the fears of the population by providing scientific explanations.

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Section: Tectonic and Geological Contextmentioning

confidence: 59%

Unprecedented seismic swarm in the Maurienne valley (2017–2019) observed by the SISmalp Alpine seismic network: operational monitoring and management

Guéguen¹,

Janex²,

Nomade³

et al. 2022

Comptes Rendus. Géoscience

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“…A kinematic connection in terms of a continuous dextral and slightly bent "Vallorcine-Valais shear zone" was proposed e.g. by Cara et al (2017). Note, however, that the dextral planes in Fig.…”

Section: Dent De Morcles (Vs)mentioning

confidence: 99%

“…The M L 3.3 and M L 3.0 earthquakes of March 20, 2017 (VAL, Fig. 2a) are part of the on-going earthquake sequence that followed the M L 4.9 earthquake of September 2005 (e.g., Deichmann et al 2006;Fréchet et al 2010;Diehl et al 2013Diehl et al , 2018Cara et al 2017). Both events on March 20 were felt by the local population and intensities reached degree IV.…”

Section: Vallorcine (France)mentioning

confidence: 99%

“…On the other hand, the along strike change of the alignment of epicentres in map view corresponds to the gentle bend of the Rhone-Simplon line possibly continuing into the "Chamonix/Mont Blanc shear zone" (CZ in Figs. 2 and 8) located between the Mont Blanc and Aiguille Rouge Massifs (e.g., Egli and Mancktelow 2013;Cara et al 2017). Either way, the Dent de Morcles earthquakes of 2018 document ongoing strike-slip deformation likely located within the Aiguilles Rouge (or Infra-Rouge) Massif.…”

Section: Dent De Morcles (Vs)mentioning

confidence: 99%

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Earthquakes in Switzerland and surrounding regions during 2015 and 2016

et al. 2018

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This report summarizes the seismicity in Switzerland and surrounding regions in the years 2017 and 2018. In 2017 and 2018, the Swiss Seismological Service detected and located 1227 and 955 earthquakes in the region under consideration, respectively. The strongest event in the analysed period was the M L 4.6 Urnerboden earthquake, which occurred in the border region of cantons Uri, Glarus and Schwyz on March 6, 2017. The event was the strongest earthquake within Switzerland since the M L 5.0 Vaz earthquake of 1991. Associated ground motions indicating intensity IV were reported in a radius up to about 50 km and locally approached intensity VI in the region close to the epicentre. Derived focal mechanisms and relative hypocentre relocations of the immediate aftershocks image a NNW-SSE striking sinistral strike-slip fault. Together with other past events in this region, the Urnerboden earthquake suggests the existence of a system of sub-parallel strike-slip faults, likely within in the uppermost crystalline basement of the eastern Aar Massif. A vigorous earthquake sequence occurred close to Château-d'Oex in the Préalpes-Romandes region in western Switzerland. With a magnitude of M L 4.3, the strongest earthquake of the sequence occurred on July 1, 2017. Focal mechanism and relative relocations of fore-and aftershocks image a NNE dipping normal fault in about 4 km depth. Two similarly oriented shallow normal-fault events occurred between subalpine Molasse and Préalpes units close to Châtel-St-Denis and St. Silvester in 2017/18. Together, these events indicate a domain of NE-SW oriented extensional to transtensional deformation along the Alpine Front between Lake Geneva in the west and the Fribourg Fault in the east. The structural complexity of the Fribourg Fault is revealed by an M L 2.9 earthquake near Tafers in 2018. The event images a NW-SE striking fault segment within the crystalline basement, which might be related to the Fribourg Fault Zone. Finally, the M L 2.8 Grenchen earthquake of 2017 provides a rare example of shallow thrust faulting along the Jura fold-and-thrust belt, indicating contraction in the northwestern Alpine foreland of Switzerland.

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“…4.8 and an epicentre located 1 km SW of Chamonix, which caused some light damage (SisFrance, 2010), and (ii) a 1905 earthquake, with M W 5.3 ± 0.3, and an epicentre located at c . 19 km from the Glacier du Géant basin, which damaged some houses and caused several rockfalls in the Chamonix valley (SisFrance, 2013; Cara et al, 2017). More recently (1962‐2016), two earthquakes with no reported damage in the Chamonix valley have been recorded near the MBM by the Bureau Central Sismologique Français: a M W 4.5–5.0 earthquake that took place in the Giffre massif, 20 km north of the Glacier du Géant basin (BCSF, 2017), and a M W 4.5 Vallorcine earthquake in 2005, 30 km north of the basin (Fréchet et al, 2010) that triggered rockfalls in the MBM (Ravanel and Deline, 2008).…”

Section: Geological Setting and Rockfall Activity Of The Mont Blanc Mmentioning

confidence: 99%

Climatic and structural controls on Late‐glacial and Holocene rockfall occurrence in high‐elevated rock walls of the Mont Blanc massif (Western Alps)

Carcaillet

Ravanel

Deline

et al. 2020

Earth Surf Processes Landf

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In the Mont Blanc massif (European Western Alps), rockfalls are one of the main natural hazards for alpinists and infrastructure. Rockfall activity after the Little Ice Age is well documented. An increase in frequency during the last three decades is related to permafrost degradation caused by rising air temperatures. In order to understand whether climate exerts a long-term control on rockfall occurrence, a selection of paleo-rockfall scars was dated in the Glacier du Géant basin [>3200m above sea level (a.s.l.)] using terrestrial cosmogenic nuclides. Rockfall occurrence was compared to different climatic and glacial proxies. This study presents 55 new samples (including replicates) and 25 previously-published ages from nine sampling sites. In total, 62 dated rockfall events display ages ranging from 0.03 ± 0.02ka to 88.40 ± 7.60ka. Holocene ages and their uncertainties were used to perform a Kernel density function into a continuous dataset displaying rockfall probability per 100years. Results highlight four Holocene periods of enhanced rockfall occurrence: (i) c. 7-5.7ka, related to the Holocene Warm Periods; (ii) c. 4.5-4ka, related to the Sub-boreal Warm Period; (iii) c. 2.3-1.6ka, related to the Roman Warm Period; and (iv) c. 0.9-0.3ka, related to the Medieval Warm Period and beginning of the Little Ice Age. Laser and photogrammetric three-dimensional (3D) models of the rock walls were produced to reconstruct the detached volumes from the best-preserved rockfall scars (≤0.91 ± 0.12ka). A structural study was carried out at the scale of the Glacier du Géant basin using aerial photographs, and at the scale of four selected rock walls using the 3D models. Two main vertical and one horizontal fracture sets were identified. They correspond respectively to alpine shear zones and veins opened-up during long-term exhumation of the Mont Blanc massif. Our study confirms that climate primarily controls rockfall occurrence, and that structural settings, coincident at both the massif and the rock wall scales, control the rock-wall shapes as well as the geometry and volume of the rockfall events.

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The 1905 Chamonix earthquakes: active tectonics in the Mont Blanc and Aiguilles Rouges massifs

Abstract: International audienc

Cited by 9 publications

References 41 publications

Unprecedented seismic swarm in the Maurienne valley (2017–2019) observed by the SISmalp Alpine seismic network: operational monitoring and management

Unprecedented seismic swarm in the Maurienne valley (2017–2019) observed by the SISmalp Alpine seismic network: operational monitoring and management

Earthquakes in Switzerland and surrounding regions during 2015 and 2016

Climatic and structural controls on Late‐glacial and Holocene rockfall occurrence in high‐elevated rock walls of the Mont Blanc massif (Western Alps)

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