Session 1 Subduction Zone Earthquake (Conveners: Jeff Freymueller and Kelin Wang)
Subduction zone earthquakes are of special importance because of their great size, destructive power, and far-reaching geodynamic effects. In addition to strong shaking, large subduction zone earthquakes may generate devastating tsunamis both locally and across ocean basins. The largest subduction earthquakes cause significant coseismic and post seismic deformation thousands of kilometers away, impacting the global reference frame and deformation studies far from the source. During the interseismic phase of the earthquake cycle, elastic deformation from the locked portion of the subduction interface extends far inland, and is variable in time due to slow slip events or other transient variations in the extent of the locked region, affecting the long-term motion and deformation of the overriding plate. Persistent creep behavior of some fault segments of various temporal and spatial scales, on the other hand, provide information on the size limits of subduction earthquakes.
Studies of the subduction zone earthquakes require the use of many geodetic tools, on land and offshore, and benefit from cross-disciplinary collaboration with seismologists. This session welcomes submissions that focus on any aspect of subduction zone earthquakes: coseismic and postseismic deformation; locking and creeping states of the interface; models for the geometry, structure, and rheology of the megathrust seismogenic zone; methods for using geodetic data in real time for earthquake or tsunami warning; or impacts of these events on the global reference frame.
Session 2 Geodetic Observations of the Earthquake Deformation Cycle: Implications for Fault Mechanics, Crust/Mantle Rheology, and Seismic Hazards (Conveners: Simon McClusky and Cécile Lasserre)
The earthquake deformation cycle includes, (1) the slow buildup of strain between earthquakes during the inter-seismic or strain accumulation period, (2) possible pre-seismic, precursory earthquake deformation, (3) instantaneous co-seismic fault offsets associated with the release of accumulated crustal strain, and (4) transient postseismic relaxation processes. Geodetic observations of earthquake cycle related deformation have been made since the 1970s using ground-based geodetic systems, and these early measurements provided a wealth of information on earthquake mechanics. During the most recent 25 years, substantial new data on the earthquake cycle deformation have resulted from a proliferation of space geodetic techniques. These techniques such as GNSS, InSAR, GRACE and assorted optical sensors have enabled continuous monitoring of seismically active regions and have provided increasingly refined observations of deformation during all phases of the earthquake cycle. New discoveries, such as the existence of slow aseismic slip during the inter- or pre-seismic phase (Slow Slip Events, creep...), shed a new light on how tectonic forces are dissipated along seismogenic fault zones. Integrating and comparing results from these different space geodetic techniques observing seismic and aseismic deformation at various temporal and spatial scales are providing new constraints on fault mechanics, and on the rheology of the Earth's lithosphere, which in turn are providing an improved physical basis for estimating and mitigating earthquake hazard.
For this session, we invite presentations based on geodetic studies of the earthquake deformation cycle. Studies that include multi mode geodetic and geologic investigations, and modeling studies that utilize a single Earth model to account for the full earthquake deformation cycle are particularly encouraged.
Session 3 Near Real-Time Warning (Conveners: Shuanggen Jin and Teruyuki Kato)
Recent great earthquakes and ensuing tsunamis have caused huge losses and hazards. The near real-time GNSS observations play a key role in rapidly estimating earthquake/tsunami and fault slip parameters as well as warning. This session is to explore the possibilities of near-field real-time onshore and offshore GNSS data in combination with strong motion and seismic data to estimate and model earthquake and tsunami processes, including earthquake/tsunami early warning and modeling. We welcome contributions on near real-time GNSS data processing, fault slip, earthquake source and tsunami modeling/warning. Papers on earthquake forecasting, early warning and real-time assessments are also welcome.
Session 4 Interaction of Earthquakes and Volcanoes (Conveners: Eric Fielding and Yusaku Ohta)
Large interplate earthquakes have often been associated with nearby volcanic phenomena occurring soon afterward. Recent dense geodetic and seismological observation also show the relationship with the large inland earthquake and high volcanic activity area. This session is to explore the interaction of earthquakes and volcanic activities over various time scales including interseismic, coseismic, and postseismic periods based on various geophysical data. We welcome a wide variety of results of relationships between earthquakes and volcanic activities based on geodetic and seismological data. Efforts related to simulation analysis and stress-change calculations with inhomogeneous structure are also welcome.
Session 5 Impact of Great Earthquakes on Reference Frame (Conveners: Richard Gross and Kosuke Heki)
Earthquakes deform the solid Earth, causing the positions of geodetic observing stations located on the Earth's surface to be measurably displaced. Since terrestrial reference frames (TRFs) are constructed from the observed positions of geodetic reference stations, earthquakes can cause distortions of TRFs unless their effects are eliminated from the station position time series. This session is a forum for discussing the effects of earthquakes on the positions of geodetic reference stations, the construction of local, regional, and global TRFs from station position time series, and the effectiveness of different strategies for mitigating the effects of earthquakes on TRFs.
Session 6 Geodetic Techniques in Volcanological Research (Conveners: Tim Wright and Takeshi Matsushima)
Using geodetic techniques, crustal deformation and mass changes at restless or active volcanoes have been traditionally monitored as a vital indicator of magma migration, volcano-tectonic interactions and/or hydrothermal unrest. Over the last two decades, there has been a dramatic increase in the quality and quantity of geodetic observations at active volcanoes. New methods have been developed, including the analysis of data from high-rate cGNSS networks, InSAR, LiDAR, tilt-meters, and volumetric strain-meters; and analysis of time variations in magnetic data and in absolute and relative gravity. The main goal of this session is to explore the impact of these new geodetic techniques on our understanding of volcanic processes, including, but not limited to, (i) the identification of precursory activity at volcanoes, (ii) the geometry of magmatic plumbing systems, (iii) the kinematics and dynamics of magma movement.We encourage discussion, refinement, and synthesis of physical and numerical models of the observed changes.
Session 7 Natural Hazards (Conveners: Manabu Hashimoto and Urs Marti)
Natural hazards occur at many different scales. Any changes that bring about the shape and mass distribution can be monitored with geodetic techniques. The goal of the investigations is a better understanding of the processes, the fostering of global observation systems and the establishment of early warning systems. For example the GRACE mission reveals changes in gravity field that relate to changes in the global water balance. LiDAR and SAR can reveal landslides of several tens to hundreds meter scale. This session welcomes a wide variety of results of application to the monitoring of natural hazards. The effort related to man-made hazards, such as ground subsidence, structural deformations etc. are also welcome.