IGOS Geohazards Workshop

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IGOS Geohazards Workshop

• Science working group report

Moderator Rosalind Helz Rapporteurs Alik
Ismail-Zadeh, Simeon Kostyanev, Pierre Briole WG
members Pascale Ultré-Guérard, Peter Collins,
Valério Tramutoli, François Schindélé
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Issues in earthquakes

• Location and size of the active faults (including
  blind faults) and the history of earthquakes on
  each.
• Is the seismic cycle model realistic or not ?
• Balance between seismic and aseismic deformation
• Mapping and interpretation of strain changes
  produced by an earthquake and the implication for
  seismic hazard
• Detection of precursors and understanding the
  physical processed that generated them inside
  Earth

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Issues in volcanoes

• To know the structure of the magmatic plumbing
  system.
• To distinguish between signal indicating an
  unrest that will lead to an eruption and noise
  (like changes in the geothermal system).
• Will precursors in long dormant volcanoes be
  similar to those in more active volcanoes ? Will
  precursors for super-volcano eruptions be
  similar ?
• To predict the characteristics of an eruption
  once it has been forecast (including size)
• To predict the evolution of an eruption once it
  has started

4
Issues in ground instabilities

• Landslides
• To detect unknown landslides, to develop
  landslides inventories
• To be able to detect small motions before
  accelerations
• To establish threshold conditions for triggering
  landslides from rainfall
• Subsidence
• To detect unknown subsiding areas
• To be able to detect changes in subsidence rate

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Compound geohazards

• Triggering of landslides by earthquakes or
  volcanic eruptions
• Triggering of a volcanic eruption by an
  earthquake
• Occurrence of lahars after large explosive
  eruptions
• Generation of tsunamis

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Issues in tsunamis

• To determine quickly the critical parameters of
  an earthquake with tsunamigenic potential
• Depth of the upper edge of the fault below the
  sea bottom
• Length of the rupture
• Slip distribution on the fault
• To be able to directly detect a tsunami
• To forecast amplitude and time of arrival of the
  waves reaching the coast

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Social issues for the geohazards

• We need to learn how to maintain awareness in the
  exposed population between rare events.
• We need to learn more about the behaviour of
  populations in areas exposed to geological risk
• We need to understand better the behaviour of
  populations after major disasters.
• We need cost/benefit analysis for the different
  geohazards

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Additional issues discussed by the group but out
of scope of IGOS-G

• Impact of very large eruptions on global weather
• Impact of long term (0.1Myr) climate change, sea
  level change, ice sheets evolution on the
  evolution of hazard

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Development/validation of new techniques

• IGOS encourages further development and expansion
  of quantitative deformation measurement
  techniques
• Continuity of InSAR missions is crucial
• Combination of GPS and InSAR
• Need better tropospheric correction
• IGOS encourages development of ground based
  radars and lidars
• IGOS encourages a critical evaluation of the
  DEMETER mission that is aimed to detect
  electro-magnetic signals associated with
  earthquakes. In particular GPS derived
  ionospheric anomalies should be used in this
  evaluation.
• IGOS encourages more research on techniques to
  evaluate the location and movement of fluids in
  the crust
• IGOS encourages the development of cross
  validation methods to combine ground and space
  based data

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Partnership and networking

• IGOS recognizes that good research requires
  strong partnership among
• Observatories and operational agencies
• Research scientists
• Space agencies
• Industry building ground and space sensors
• Emergency authorities
• IGOS recognises that networking activities are
  especially important to support near real time
  analysis and modelling of data

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Some specific recommendations to help science for
geohazards

• Data bases
• IGOS recommends that volcano observatories
  participate in the development of WOVOdat
  project.
• IGOS recognizes the need for improved historical
  archives for all geohazards (comparable to the
  Global Volcanism Project).
• IGOS encourages co-location of sensors (example
  seismic and GPS data acquired at the same
  location)
• IGOS encourages the development of facilities to
  feed science community with InSAR and PS-InSAR
  interferograms produced on a routine basis