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GGOS Topical Meeting on Geohazards

The GGOS Topical Meeting on Geohazards will take place on 2 October 2026 in Gävle, Sweden. The meeting will consist of three 1.5-hour sessions, each beginning with key solicited presentations, followed by a discussion. Both on-site and remote participation will be possible.

The GGOS Topical Meeting on Geohazards is scheduled to take place the day after the IAG Commission 3 Symposium on “Tracking and Investigating Geodynamics and Earth Rotation” (TIGER Symposium, https://geodesy.science/com3/meetings/tiger-symposium-2026/). As this Symposium includes sessions on Cryospheric Deformation, Volcanogeodesy and Seismogeodesy, experts from the International Association of Cryospheric Sciences (IACS), the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), and the International Association of Seismology and Physics of the Earth’s Interior (IASPEI) will have the opportunity to participate in the GGOS Topical Meeting.

In the week after the GGOS Topical Meeting, the GGOS Days 2026 will take place at the same venue, see https://geodesy.science/events/ggos-days-2026/. Those attending the GGOS Topical meeting are also welcome to participate in GGOS Days 2026.

Through the Global Geodetic Observing System (GGOS), the International Association of Geodesy (IAG) provides a common framework to encourage, coordinate and facilitate Earth-monitoring efforts based on geodesy. This framework aims to integrate observations and geodetic outputs from different national and international organisations, while also raising awareness of geodesy and its products. A key strategic objective of GGOS is to facilitate the incubation of new, integrated research topics supported by geodesy that address emerging scientific and societal challenges. To this end, GGOS promotes the establishment of GGOS Focus Areas. These address broader, cross-disciplinary issues, developing new methods, designing integrated data analysis, and identifying potential new geodetic products. Current GGOS Focus Areas include

The Focus Area on Geohazards Monitoring currently focuses on GNSS-enhanced Tsunami Early Warning Systems (GeTEWS), particularly in Oceania, which is one of the most seismically active regions. Developments of this Focus Area have been instrumental in raising the profile of geodesy within important international bodies such as the Pacific Geospatial Surveying Council (PGSC), the GeoRisk Commission of the International Union of Geodesy and Geophysics (IUGG), the IUGG Joint Tsunami Commission, the UN Sendai Framework for Disaster Risk Reduction, and the UN International Committee on GNSS. The outcomes of this Focus Area have also contributed to the Global Assessment Reports on Disaster Risk Reduction (GAR), which are regularly published by the UN Office for Disaster Risk Reduction (UNDRR).

Given the success of the Geohazards Monitoring Focus Area with GeTEWS, GGOS is eager to extend its remit by exploring further ongoing and prospective applications of geodetic techniques and methods for monitoring natural hazards. The goal is to evaluate the feasibility of transforming ongoing and future scientific research outcomes into operational services. GGOS is particularly interested in approaching experts in Interferometric Synthetic Aperture Radar (InSAR) techniques, as well as regional infrastructures for geohazard monitoring based on geodetic methods. While most monitoring activities rely on satellites and space-based sensors, this Topical Meeting should emphasise in-situ measurements and existing terrestrial monitoring sites and networks.

Programme

The use of geodetic techniques to monitor natural hazards is well documented in scientific research and public literature. Further improvements are discussed at regular science-driven conferences. The GGOS Topical Meeting focuses on effectively applying research results to early warning programmes. These include the challenges of long-term deployment and operation of observation networks and sensors, data archiving and analysis capabilities, implementation of real-time services and usability of geodetic outputs in emergency response programmes. Key invited speakers will summarise the current challenges in their field of expertise, and discussions in a round-table format will identify areas in which GGOS could contribute towards overcoming these challenges. The meeting will consist of three 1.5-hour sessions, each beginning with key solicited presentations, followed by a discussion. Both on-site and remote participation will be possible.

Speaker

Anna_Riddell

Matt Garthwaite

Mahdi Motagh

Lorenzo Solari

Keisho Ito

John Dehls

Hanssen Ramon

Glen Mattioli

Franz Meyer

Fracesco Caso

Basara Miyahara

Presentations

08:30 – 10:15 | Session 1 – InSAR Key Applications

Chair: Faramarz NILFOUROUSHAN | University of Gävle, Senior Geodesist at Lantmäteriet | Sweden

Abstract:

In classical geodesy, network design is the process of ensuring that a measurement system is fit for purpose. It determines whether meaningful, reliable, and interpretable information can be derived from the observations. This relates to the location of the observation points, whether the estimated parameters adequately represent the objectives of the survey, which parameters are observable, with what precision and reliability, under which assumptions, and whether competing hypotheses can be distinguished. In contrast, these principles are rarely discussed explicitly in the InSAR community. This is understandable: the satellite observations have already been acquired, seemingly leaving little opportunity to “design” the measurement network other than through future satellite missions with different viewing geometries, wavelengths, or revisit frequencies. This perception, however, overlooks a fundamental aspect of InSAR. Every InSAR application is, in fact, a geodetic network design problem, through the selection of coherent scatterers, reference objects, acquisition geometries, temporal sampling, estimation models, external observations, and prior information. These design choices determine not only the precision of the estimated parameters but, more fundamentally, whether the quantity of interest is observable and whether the resulting estimates are representative of the underlying physical process. The presentation further argues that InSAR does not merely require classical geodetic network design; it extends the concept itself. Traditionally, network design addresses where, what, and how accurately observations should be made to answer a predefined question. InSAR introduces additional design dimensions, including which radar targets become observations, how temporal coherence is exploited, which prior information and physical constraints are incorporated, and how heterogeneous observations are integrated into a single estimation problem. Consequently, network design evolves from the design of an observation network to the design of the complete estimation problem. The central thesis of this presentation is therefore that geodetic network design does exist in InSAR—it is simply not recognized as such. As a consequence, many InSAR studies focus on improving estimation algorithms while paying insufficient attention to whether the measurement system itself is capable of answering the intended question. Failure to recognize these design choices may explain why similar datasets sometimes lead to conflicting interpretations, why the validity of InSAR-derived products is occasionally questioned, and why confidence in operational applications varies considerably between stakeholders. Recognizing InSAR as an implicit geodetic network design problem fundamentally changes the role of the geodesist. Rather than contributing only to estimation algorithms, geodesists become responsible for ensuring that InSAR measurement systems are fit for purpose. This perspective has important implications for technology development, operational implementation, standardization, education, economic competitiveness, and ultimately the societal trust, confidence, and adoption of InSAR. The presentation concludes with a call for greater involvement of the geodetic community in shaping the future of InSAR.

Franz Meyer

Abstract:

The advent of modern SAR sensors such as NISAR and Sentinel-1 with their global observation strategies and free-and-open data policies has ushered in an era of unprecedented data volumes, offering immense potential for global geohazard monitoring. However, transforming these massive data streams into operational decision-support assets for the disaster monitoring community presents significant bottlenecks. Chief among these are (1) the sheer scale of data, often requiring high-performance cloud-based solutions; (2) the complexity of processing workflows that can deter non-expert end-users; (3) the need for community training to ensure the accurate interpretation of derived deformation products; and (4) the technical imperative for robust processing pipelines capable of mitigating pervasive nuisance signals such as atmospheric phase delays and temporal decorrelation. This presentation explores how a suite of interconnected, NASA-funded InSAR initiatives are actively tackling these hurdles to operationalize satellite geodesy and advance the uptake of InSAR by the disaster monitoring community. We highlight scalable cloud-computing architectures developed at the Alaska Satellite Facility (ASF) to enable continental- to global-scale InSAR processing efforts. We discuss a volcano geodesy project funded by the NASA MEaSUREs program and led by Stanford University that creates standardized geodetic observations for all active volcanoes on Earth. We introduce the North America-scale automated displacement products created by the JPL-led OPERA project, which map displacements of various origins and spatio-temporal expressions using InSAR time series data. Finally, we discuss the NASA Disasters “VolcSARvatory” program, which provides customizable InSAR solutions, delivers accessible, analysis-ready products, and embeds them directly into end-user decision-support platforms. By addressing both backend processing challenges and frontend user-integration strategies, these efforts explore different pathways to transition InSAR from a research tool into an operational hazard monitoring resource. We will show examples from these projects, demonstrate their capabilities and limitations, and conclude with a summary of potential next steps.

Matt Garthwaite

Abstract:

Interferometric Synthetic Aperture Radar (InSAR) has evolved from a specialist research technique into a mature Earth observation capability with the potential to support operational geohazard monitoring at regional to global scales. However, transitioning InSAR from a scientific product to trusted public infrastructure remains a significant challenge. This presentation will explore the technical, organisational and governance considerations required to establish sustainable InSAR-based services that support critical systems and informed decision-making. Drawing on experiences from national-scale geospatial and Earth observation initiatives, the presentation will discuss the role of automated processing systems, quality assurance frameworks, calibration and validation activities, integration with geodetic observations, and the growing importance of cloud-native analytical platforms. Examples from earthquake, land deformation and infrastructure monitoring applications will be used to illustrate both opportunities and remaining challenges. The presentation will conclude by considering future pathways for integrating InSAR within operational geodetic and geospatial observing systems, and the role that the international geodesy and Earth observation communities can play in supporting the transition from scientific capability to sustained public service.

10:45 – 12:30 | Session 2 – Continuous Monitoring Based on InSAR

Chair: Ramon HANSSEN, Delft University of Technology, The Netherlands

Keisho Ito

Abstract:

ALOS-4, launched by JAXA in 2024, is an Earth observation satellite equipped with the L-band synthetic aperture radar PALSAR-3. The mission advances the long-term L-band SAR observation series established by ALOS and ALOS-2. PALSAR-3 provides wide-area imaging capability while maintaining fine spatial resolution, and its continuous surface observations, independent of weather conditions and daylight, are being applied to the detection and understanding of surface deformation associated with earthquakes, volcanic activity, landslides, land subsidence, and other phenomena. This presentation provides an overview of ALOS-4/PALSAR-3 and its current operational status, and reports on its applications to crustal deformation and geohazard monitoring. In particular, the presentation focuses on interferometric SAR, highlighting the characteristics of L-band SAR, the significance of wide-area and frequent observations, rapid observations after disaster events, and the applicability of ALOS-4 to continuous deformation monitoring. Through actual observation results and use cases, this presentation will show how ALOS-4 observation data can contribute to disaster response and area-wide understanding of surface deformation.

Fracesco Caso

Abstract:

We present the activities of the EPOS Satellite Data Thematic Core Service (SATD-TCS) dedicated to Earth surface displacement monitoring. The SATD-TCS primarily exploits Interferometric Synthetic Aperture Radar (InSAR) techniques to provide deformation maps for the analysis of single events, and displacement time series for investigating the temporal evolution of deformation phenomena. We provide different examples of the SATD-TCS products relevant to real case studies including volcanoes, earthquakes, and landslides. Finally, to overcome some of the InSAR limitations, we show how complementary observations, such as those provided by Global Navigation Satellite Systems (GNSS), can be integrated to calibrate the InSAR products and retrieve three-dimensional ground displacement fields.

John Dehls

John Dehls(1), Gökhan Aslan(1), Line Rouyet(2), Marie Bredal(1), Tom Rune Lauknes(2), Lotte Wendt(2), Daniel Stødte(2), Heidi Hindberg(2), Jelte von Oostveen(2), Yngvar Larsen(2), Emma Hauglin(1), Dag Anders Moldestad(3)

(1)Geological Survey of Norway (NGU), (2)NORCE Norwegian Research Centre AS, (3) Norwegian Space Agency

Abstract:

Operational InSAR-based ground motion services have become an established component of national and continental-scale geohazard monitoring. Services such as InSAR Norway and the European Ground Motion Service (EGMS) demonstrate how systematic processing of Sentinel-1 data can provide regularly updated information on ground deformation for a wide range of applications, including landslides, subsidence, infrastructure monitoring and natural hazard assessment. Extending these approaches to Arctic environments introduces new challenges related to seasonal snow cover, strong seasonal deformation signals, sparse infrastructure, and rapidly changing permafrost conditions. The InSAR Svalbard Ground Motion Service was developed to address these challenges and provide systematic deformation monitoring across selected areas of the High Arctic. Based on Sentinel-1 time-series analysis, the service combines seasonal and interannual displacement products to characterize both short-term thaw-related deformation and longer-term ground stability trends. The current implementation covers key settlements, research stations, infrastructure corridors and geomorphologically active areas in western and central Spitsbergen. This presentation discusses the development of the service within the broader context of operational ground motion monitoring. Particular attention is given to the adaptations required for continuous permafrost environments, the challenges of sustaining operational monitoring in remote regions, and the role of long-term InSAR observations in supporting hazard assessment, infrastructure management and climate-change adaptation in the Arctic.

Mahdi Motagh

13:30 – 15:15 | Session 3 – Regional Initiatives Integrating GNSS and InSAR Techniques

Chair:

Lorenzo Solari

Abstract:

The European Ground Motion Service (EGMS), a product part of the Copernicus Land Monitoring Service, provides harmonised, pan-European measurements of ground deformation based on InSAR data from Sentinel-1 satellites. Its portfolio includes three data layers: Basic, Calibrated, and Ortho. The Basic product delivers line-of-sight deformation measurements, the Calibrated product aligns these to a geodetic reference frame derived from thousands of GNSS stations in Europe, and the Ortho product transforms this information into the vertical and horizontal components of the motion. A key element of EGMS production is the integration of GNSS data, which provides absolute positioning information to calibrate and stabilise the InSAR-derived measurements. Operationally, EGMS is updated on yearly basis and follows precise quality control rules, and it is regularly validated.

Glen Mattioli

Abstract:

The EarthScope Consortium formed in 2023 with the merger of two antecedent nonprofit consortia, the Incorporated Research Institutions for Seismology (IRIS) and UNAVCO, each with a long history of support for geophysics research and education. EarthScope was selected by the National Science Foundation (NSF) to be the operator of the newly established National Geophysical Facility (NGF) in June 2025 after a lengthy and rigorous peer-reviewed process. The NSF NGF began operation on October 1st, 2025, and supports a diverse portfolio of activities, including providing geophysical instrumentation and engineering to support independently funded research and educational activities, global and regional geophysical sensor networks (e.g. the Global Seismological Network and NASA Global GNSS Network), the Network of the Americas (NOTA) hemispherical scale GNSS network, data and metadata management of global seismic and geodetic networks and experiments, with an emphasis on Analysis Ready – Cloud Optimized data products, architectures, and systems, along with a large portfolio of community engagement activities to enhance user access to NSF NGF resources, providing training and short courses for all user levels, and workforce development through formal internship programs and partnerships with educational institutions. EarthScope, with funding from the USGS, also provides operational support for the geodetic component of ShakeAlert, the US earthquake early warning system in the states of Washington, Oregon, and California. The vision of EarthScope as the operator of the NSF NGF is to provide seamless services that are cross-disciplinary, adaptive, and highly efficient and that can be scaled and customized to meet a wide range of user needs and skill levels. My presentation will focus on the long history of support for geohazards monitoring and research, the current capabilities and role of NSF NGF within Global Geodetic Observing System (GGOS), and the vision to expand those capabilities over the current five-year award from NSF and into the decades beyond. Specific examples from the major components of NSF NGF will be discussed as they relate to GGOS and geohazards.

Basara Miyahara

Abstract:

GNSS and InSAR are both critical tools for capturing the spatiotemporal characteristics of Earth’s geodynamics. GNSS is a powerful technique for monitoring precise coordinate time series at observation sites, whereas InSAR has a significant advantage in providing spatially continuous snapshots of crustal deformation and surface displacement. The Geospatial Information Authority of Japan (GSI) operates a nationwide network of approximately 1,300 GNSS continuously operating reference stations (CORS) and monitors crustal dynamics across Japan using both real-time and post-processed solutions. In addition, GSI routinely performs InSAR time-series analysis using ALOS-2 and ALOS-4 data covering Japan in collaboration with JAXA. These two complementary geodetic techniques are optimally integrated to support the monitoring and assessment of seismic and volcanic hazards in Japan. This presentation will demonstrate how the combined use of GNSS and InSAR contributes to disaster risk reduction and hazard mitigation efforts in Japan.

Anna Riddell

Abstract:

From creeping faults to sinking cities, geohazards leave measurable fingerprints on the Earth’s surface. Australia and New Zealand are increasingly leveraging the complementary strengths of GNSS and InSAR to monitor, understand, and respond to a wide range of geohazards. From millimetre-scale deformation measurements to regional monitoring services, this presentation will share lessons learned, innovative applications, and future opportunities for integrating geodetic observations into hazard management. Featuring examples from national programmes, collaborative research, and operational services, the session will explore the growing role of modern geodesy in hazard detection, situational awareness, and community resilience.

Dates

Schedule and conference program31 August 2026
Registration deadline (on-site participation)6 September 2026
On-site participation confirmation15 September 2026
List of participants 15 September 2026
GGOS Topical Meeting2 October 2026

Registration

All colleagues working on the topics of the meeting or related themes are invited to participate on-site or online. Attendance is free of charge (no registration fee), but pre-registration is required to ensure room capacity and to coordinate the online communication.

By pre-registering, the participants agree that their data will be stored internally in the GGOS records. The data will only be used for meeting-related organisational issues. On-site participation will be confirmed before 15 September. If any pre-registered participant is not able to attend the meeting, they are asked to withdraw their pre-registration as soon as possible (by contacting us). Please note that the free participation is only valid for the GGOS Topical Meeting on Geohazards (2 October 2026).

To attend the entire TIGER Symposium, a registration fee is required (see TIGER event website). GGOS Topical Meeting attendees interested to join the Volcano- and/or Seismogeodesy Sessions of the TIGER Symposium (on 1 October 2026) can register free of charge via the GGOS Topical Meeting.

Note: Please note that Russian and Belarusian nationals currently working in Russia and/or Belarus are welcome to participate online, but cannot attend the meetings in person due to the venue being hosted by a Swedish governmental agency.

Register here for GGOS Topical Meeting

Registration Deadline: 6. September 2026


Travel

Venue

The GGOS Topical Meeting on Geohazards will be hosted by Lantmäteriet, the Swedish Mapping, Cadastral and Land Registration Authority (https://www.lantmateriet.se/en/), located in:

Lantmäterigatan 2C, 802 64 Gävle, Sweden

Gävle (Sweden) is located about 150 km to the north of Stockholm. More information about the city can be found at https://www.visitgavle.se/en.

Arrival

By air : The closest airport is Stockholm Arlanda Airport (airport code ARN), which has daily connections to many European and worldwide destinations through scheduled services of a large number of international airlines. It is the largest airport in Sweden. The airport has frequent train connections to Gävle via the station Arlanda C, which is located between the terminals 5 and 4.

By train: Gävle’s railway station is located very close to the city centre. Timetables and tickets are supplied by SJ, https://www.sj.se/en.

By car: Those wishing to drive to Gävle need to enter the Scandinavian peninsula taking either a ferry to Gothenburg, Stockholm or Trelleborg, or using the Øresund Bridge, the connection between Denmark (Copenhagen) and Sweden (Malmö).

Accommodation

Information about hotel reservation will be provided to on-site participants later.

Visa

Sweden is a member of the European Union; therefore, no visa is needed for E.U. citizens. Non ‐ E.U. participants should contact their nearest Swedish Embassy or Consulate for further information. For a complete list of countries who do need to apply for a visa, check https://www.government.se/government-policy/migration-and-asylum/list-of-foreign-citizens-who-require-visa-for-entry-into-sweden/. If you do need a visa, please visit https://www.government.se/government-policy/migration-and-asylum/information-on-visas/ to find more details. Those who require a formal invitation for the purpose of obtaining a visa, or raising travel funds in their country, may contact the organisation team  . Only those participants who have confirmed their contribution to the GGOS Topical Meeting will receive a formal invitation letter. Travel and medical insurance, if required, are the sole responsibility of the participant.

Contact

GGOS Coordinating Office, contact form

Coordination team

  • Laura Sánchez, President of GGOS, Technische Universität München, Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), Germany
  • Rebekka Steffen, President IAG Commission 3 “Earth Rotation and Geodynamics”, Lantmäteriet, Sweden
  • Constanza Santori, Early Career Scientist Representative, Universidad de Chile, Chile
  • Holger Steffen, EPOS TCS GNSS Executive Board Chair, Lantmäteriet, Sweden
  • Faramarz Nilfouroushan, Senior lecturer, University of Gävle, Sweden
  • Martin Sehnal, Director of the GGOS Coordinating Office, BEV – Federal Office of Metrology and Surveying, Austria

Code of Conduct

GGOS follows the Code of Conduct of the International Union of Geodesy and Geophysics (IUGG) and their anti-harassment guidelines. These code and guidelines apply for all GGOS meetings. GGOS opposes any discrimination or harassment based on such factors as age, citizenship, disability, ethnic origin, gender identity, language, political or other opinion, religion, or sexual orientation. We will follow IUGG’s Anti-Harassment Guidelines to prevent any form of harassment or discrimination, and to ensure an inclusive atmosphere that encourages the free expression and exchange of scientific ideas and results.

All attendees of GGOS meetings have a role to play in creating an inviting and harassment-free environment through their own behaviour and by discouraging harassment and discrimination by others.

Expected Behaviour

  • All attendees are treated with respect and consideration, valuing a diversity of views and opinions.
  • The meeting creates an environment to allow for the professional exchange of information.
  • Be considerate, respectful and collaborative. Communicate openly with respect for others, critiquing ideas rather than individuals.
  • Avoid personal attacks directed toward other attendees, the local organisers or guests. Be mindful of your surroundings and of your fellow participants.
  • Alert the local organisers if you notice a dangerous situation or someone in distress.

Unacceptable Behaviour

  • Discrimination, harassment or intimidation is unacceptable and will not be tolerated. The local organisers may take any action necessary and deemed appropriate (see below) if attendees engage in unacceptable behaviour including removal from the meeting without warning or refund.
  • Recording or taking photography of another individual’s presentation without the explicit permission of the authors is not allowed.
  • Disruption of talks at oral or poster sessions, any receptions, or satellite events within the meeting in other venues.

Reporting Unacceptable Behaviour

  • If you are the subject to unacceptable behaviour or may have witnessed such behaviour that violates professional and respectful participant conduct, please immediately notify the chairperson of the session if the incident has occurred during the meeting or local organisers.
  • Notification can be done by contacting a local organiser on-site (e.g. at the registration desk) or you can e-mail your concern by contact form.
  • All reports will remain confidential.

Actions to prevent unacceptable behaviour

  • If a clear case of verbal discrimination, harassment or intimidation during a scientific session is established to have occurred, the Chairperson should act immediately to stop it. If the situation deteriorates, the Chairperson should ask the offender to leave the room.
  • If any form of harassment occurs in a less openly visible way (e.g. during social activities or informal gatherings), the affected person and/or witness(es) should immediately report it to one of the organisers. The affected person has the option to pursue a formal procedure.
  • In cases described above, the organiser should prepare written notes of the incident, attaching any evidence and identifying any witnesses. The organiser should then give the alleged offender the opportunity to be heard and to respond to the allegation.
  • A full report of the incident should then be sent to the organisers via contact form
  • , who will promptly report to the IAG and IUGG Officers any case of harassment that occurred during an IAG or IUGG-supported meeting.
  • Harassment incidents or behaviour that occur outside IAG or IUGG activities referred to above will be considered only when a formal investigation of the case has been conducted by the relevant authority (e.g. the institution, to which the individual is affiliated) and made known to the IAG and IUGG Executive Committees. In those cases that involve an IUGG or Association officer, the Executive Committee may decide to take disciplinary actions against that person.