Surface rupture and shallow fault reactivation during the 2019 Mw 4.9 Le Teil earthquake, France

Ritz, Jean‐François; Baize, Stéphane; Ferry, Matthieu; Larroque, Christophe; Audin, Laurence; Delouis, Bertrand; Mathot, Emmanuel

doi:10.1038/s43247-020-0012-z

Cited by 70 publications

(92 citation statements)

References 40 publications

(39 reference statements)

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“…The inverted depth lies around 1 km and the calculated moment magnitude is Mw 4.8 (Vallage et al, 2020), which is in agreement with other publications (Ritz et al, 2020;Cornou et al, 2021) and with rapid estimations from different French institutes such as OCA (Mw 4.9, 1 km) and IPGP (Mw 4.8, 3 km). The moment magnitude estimated from coda wave analysis at 14 LDG stations is slightly higher (Mw coda 5.2), in between the ML and the other moment magnitudes (Tab.…”

Section: Le Teil (2019)supporting

confidence: 92%

See 1 more Smart Citation

A decade of seismicity in metropolitan France (2010–2019): the CEA/LDG methodologies and observations

Duverger¹,

Mazet‐Roux²,

Bollinger³

et al. 2021

BSGF - Earth Sci. Bull.

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We summarize ten years of the French seismicity recorded by the Geophysical and Detection Laboratory (LDG) of the French Alternative Energies and Atomic Energy Commission (CEA) network from 2010 to 2019. During this period, 25,279 natural earthquakes were detected by the LDG and located within metropolitan France and its immediate vicinity. This seismicity contributes to more than 47% of the natural earthquakes instrumentally recorded since 1962 (mainly due to the improvement of network capacity), and includes about 28% of the most significant earthquakes with a magnitude ML ≥ 4.0. Recent seismic events therefore significantly expand the available national catalogues. The spatial distribution of 2010-2019 earthquakes is broadly similar to the previous instrumental pattern of the seismicity, with most of the seismic activity concentrated in the French Alps, the Pyrenees, the Brittany, the upper Rhine Graben and the Central Massif. A large part of the seismic activity is related to the occurrence of individual events. The largest earthquakes of the last ten years include the November 11, 2019 Le Teil earthquake with ML 5.4 and maximal epicentral intensities VII to VIII, which occurred in the Rhone valley; the April 28, 2016 La Rochelle earthquake with ML 5.2 and epicentral intensity V, which occurred at the southernmost extremity of the Armorican Massif in the vicinity of the Oléron island; and the April 7, 2014 Barcelonnette earthquake with ML 5.1 and epicentral intensity VII, which occurred in the Ubaye valley in the Alps. In 2019, two other moderate earthquakes of ML 5.1 and ML 4.9 stroke the western part of France, in Charente-Maritime and Maine-et-Loire department, respectively. The recent moderate earthquake occurrences and the large number of small earthquakes recorded give both the potential to revise some regional historical events and to determine more robust frequency-magnitude distributions, which are critical for seismic hazard assessment but complex due to low seismicity rates in France. The LDG seismic network installed since the early 1960s also allows a better characterization of the temporal structure of seismicity, partly diffused and in the form of mainshock-aftershocks sequences or transient swarms. These aspects are important in order to lower the uncertainties associated to seismogenic sources and improve the models in seismic hazard assessment for metropolitan France.

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Section: Le Teil (2019)supporting

confidence: 92%

“…Ultimately, InSAR measurements made with Sentinel 1 imagery clearly highlight surface deformation located on the Rouvière fault. The InSAR inversion revealed that the maximum amount of slip was localized at about 1 km depth and displacements were observed up to the surface (Vallage et al, 2020;Ritz et al, 2020).…”

Section: Le Teil (2019)mentioning

confidence: 99%

A decade of seismicity in metropolitan France (2010–2019): the CEA/LDG methodologies and observations

Duverger¹,

Mazet‐Roux²,

Bollinger³

et al. 2021

BSGF - Earth Sci. Bull.

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“…For this reason, we incorporate the fault portion containing the Alviela trench in all modeled seismic scenarios. However, we cannot rule out the possibility of an unrecorded lower-magnitude earthquake affecting the trench area since the M4.9 Teil earthquake ruptured to the surface (Ritz et al, 2020), despite that probably being a rare phenomenon.…”

Section: Discussionmentioning

confidence: 89%

Evidence of Surface Rupture Associated With Historical Earthquakes in the Lower Tagus Valley, Portugal. Implications for Seismic Hazard in the Greater Lisbon Area

Canora

Vilanova²,

Pro-Díaz

et al. 2021

Front. Earth Sci.

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The Lower Tagus Valley Fault, Portugal, has long been associated with the damaging earthquakes that affected the Greater Lisbon Area in historical times. These include a poorly documented earthquake that occurred in 1344, the relatively well-documented 1531 earthquake, and the most recent M6.0 1909 earthquake. In this work, we use a 0.5 m resolution LiDAR-based digital elevation model and a 0.5 cm resolution digital surface model based on UAV photogrammetry to accurately locate the fault scarps in the northernmost portion of the western fault strand and to select sites to perform paleoseimolological investigations. The paleoseismological and geochronological analysis performed in the Alviela trench site document the fault activity in the last 3000 years, including two earthquakes during historical times. We performed ground motion scenarios for 20 km, 40 km, and 60 km ruptures including the trench site. The ground motion fields obtained for the 40 km and 60 km ruptures are in agreement with most macroseismic intensity data available for the 1531 earthquake, implying a magnitude in the range M6.8–7.4. However, the degree of deformation preserved in the trench suggests a value closer to the lower magnitude bound. The intensity level observed in Lisbon in 1531 (IX) is lower than the modeled intensities for all considered scenarios and could be related to a particularly high level of vulnerability of the building stock.

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“…On November 11th 2019, the Mw 4.9 Le Teil earthquake occurred at a very shallow focal depth on a southeast-dipping reverse-fault. Field surveys and InSAR analysis show evidence for a discontinuous surface rupture with a length of about 5 km and up to 15 cm of co-seismic uplift (Ritz et al, 2020). However, detailed geomorphic analysis of a 25-cm-resolution DEM obtained from a LiDAR survey, carried out only 10 days after the earthquake, failed to yield complete evidence of surface ruptures.…”

Section: -Shear Zone Thickness and Past Tectonic Activitymentioning

confidence: 99%

“…However, the nature of seismogenic deformations in southeastern France remains unclear. For example, the 2019 November 11th Le Teil earthquake (see figure 1 for location) raises the question of the seismic loading and seismic source that can trigger such events in very low slip rates/shallow deformation contexts and of faults that have not experienced ruptures during the Late Quaternary (Ampuero et al, 2020;Ritz et al, 2020). This highlights the fact that faults capable of creating surface ruptures can currently remain unnoticed because of very long recurrence intervals.…”

Section: -Introductionmentioning

confidence: 99%

Assessing post-pliocene deformation in a context of slow tectonic deformation: insights from paleoseismology, remote sensing and shallow geophysics in Provence, France

et al. 2020

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The Provence region, located in the southeast of France, has experienced a few destructive earthquakes during the last centuries, such as the 1909 Lambesc earthquake or the 1509 and 1708 Manosque earthquakes. However, faults in the area experience slow slip rates (< 0.1 mm/yr) that preclude quantification of deformation using geodetic measurements. Active faults in Provence have long recurrence intervals and the region experiences erosion under a Mediterranean climate where surface markers of such deformation are rapidly erased. As a consequence, several faults in the region may go unnoticed despite having the potential to generate earthquakes. This work focuses on the Vinon-sur-Verdon area in Provence, where a relatively narrow fault structure, the Maragrate fault, brings into contact Miocene clays and Pliocene conglomerates. Because of its proximity to a major nuclear research facility, this fault poses a potential earthquake hazard that justifies studies aimed at gaining insight into its mechanics and Quaternary seismic activity. In this context, a multi

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Surface rupture and shallow fault reactivation during the 2019 Mw 4.9 Le Teil earthquake, France

Cited by 70 publications

References 40 publications

A decade of seismicity in metropolitan France (2010–2019): the CEA/LDG methodologies and observations

A decade of seismicity in metropolitan France (2010–2019): the CEA/LDG methodologies and observations

Evidence of Surface Rupture Associated With Historical Earthquakes in the Lower Tagus Valley, Portugal. Implications for Seismic Hazard in the Greater Lisbon Area

Assessing post-pliocene deformation in a context of slow tectonic deformation: insights from paleoseismology, remote sensing and shallow geophysics in Provence, France

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