Seismic Insights from the Southern Alps : 70 Sensors in Action



As part of the MADALPS project, funded by the French National Research Agency (ANR), a team of 13 scientists deployed a dense temporary seismic sensor network in October 2025 between France and Italy, in the heart of the Southern Alps. This network, consisting of 70 sensors, is the result of a collaboration between ISTerre (44 sensors), Géoazur (16 sensors), and the French Nuclear Safety and Radioprotection Authority (ASNR, 10 sensors). Its goal is to better understand the region’s seismic activity by recording micro-earthquakes with high precision, which result from active geological deformation.
Figure 1 : Seismicity map of the Ubaye Valley (January 2024 – January 2026)
This map shows the spatio-temporal distribution of seismicity recorded in the study area over a two-year period, from January 1, 2024, to January 31, 2026. The seismic data come from the SISmalp/OSUG network (Observatory of the Sciences of the Universe, Grenoble).




The acquired data will help improve our understanding of the tectonic processes responsible for earthquakes in this highly active Alpine region, as well as enhance imaging of the Earth’s crust.


The Ubaye Valley is known for its high seismicity. Historically, it was affected by a magnitude 5.5 earthquake in 1959 at Saint-Paul-sur-Ubaye and has experienced several major earthquake swarms, notably in 2003–2004, 2012, and 2014–2015, reaching a magnitude of 4.8 in 2014 Sismalp.


More recently, between August 2024 and January 2025, the region experienced an intense seismic crisis : nearly 15,300 earthquakes were recorded by the permanent Sismalp network, including a magnitude 4 event beneath the Brec de Chambeyron.


To increase precision and uncover the physical mechanisms behind this seismicity, the MADALPS project deployed an exceptional temporary network. This network is the result of close technical collaboration among three major partners :

  • ISTerre (ISTerre – OSUG, CNRS / IRD / UGA / Univ. Savoie Mont-Blanc / Univ. Gustave Eiffel) : 44 sensors
  • Géoazur (Université Côte d’Azur /Observatoire de la Côte d’azur/ CNRS / IRD) : 16 sensors
  • L’ASNR (L’Autorité de sûreté nucléaire et de radioprotection) : 10 sensors


    Before deployment in the field, all equipment and instrumentation were prepared and tested by the technical teams of the partner laboratories, ensuring reliable recordings and smooth execution of the mission.


    From October 8 to 19, 2025, the teams (engineers, PhD students, and researchers) traveled through the Ubaye Valley and Queyras (France), as well as the Stura and Maira valleys (Italy), to install the stations by vehicle or, in areas with difficult access, on foot, to cover the area of interest as uniformly as possible.



Figure 2a : Temporal frequency of seismicity in the Ubaye Valley (1990–2026)
Figure 2a shows the monthly evolution of seismic activity in the Ubaye Valley over 36 years, with a total of 40,000 events recorded by the SISmalp network (OSUG). Activity remains moderate until 2010, followed by three major seismic crises in 2012 (≈900 events/month), 2014 (≈3,000 events/month), and 2024–2025 (>3,300 events/month).
Each seismic station consists of three main components : a sensor, a digitizer, and a self-contained power supply composed of three batteries totaling around 15 kg, enabling continuous data recording for nine months, including under challenging conditions such as snow.

The sensors record ground motion continuously until their planned retrieval in May 2026, nine months after installation. This temporary network complements the permanent seismic networks, providing an unprecedented density of observations in the region.

This network will lower the seismic detection threshold, provide more precise earthquake locations, and improve knowledge of active faults, helping to better understand the ongoing tectonic processes in the Southern Alps.




Local scientific contacts: :

• Agnès Helmstetter
• Christian Sue
• Eloïse Granier

Géoazur contacts

• Maxime Godano : godano geoazur.unice.fr
• Christophe Laroque : christophe.larroque univ-cotedazur.fr

ASNR contacts

• Hervé Jomard : herve.jomard irsn.fr









Image of the team and equipment during the installation of seismic stations in the field campaign