President's Page: Connecting the world of to near-surface geophysics

Since 1930, SEG has been the world's leading promoter of applied geophysics and supporter of practicing geophysicists. Over that 90-plus-year period, the Society has adapted effectively to changing member needs and industry expectations. SEG and the majority of professionals it serves have been at the heart of exploring for and discovering the energy that has powered the economic revolution of the last three-quarters of a century.

President's Page: Facing The Future: Securing SEG Relevance and Impact

A fourth digital revolution of applied geophysics is upon us — the “big data” era. Three prior digital revolutions in the past 50 years have provided new and more powerful tools, expanded markets, and redefined what it takes to be a successful applied geophysicist. The present digital revolution can do the same and be a benefit to the profession. To meet this challenge, SEG is adapting its business, products, and services.

The tilt and strainmeter network of NE Italy: multi-decadal observations of crustal deformation as ground truth for DinSAR.

<p>Decade-long series of tilt- and strain-meter observations in NE Italy allow monitoring the crustal deformation from short transient to long-term phenomena. These recordings, some of them started in 1960, are generated by sources spanning a wide spectrum of spatial scales, such as sudden underground flooding due to extreme rainfall [1, 2], years-long fluid diffusion transients due to fault behavior [3], the free oscillation arising from megathrust earthquakes (e.g. Chile 1960, Sumatra 2004, Tohoku 2011).<br>The instrumental sites lie on karst formations, in an area of continental collision and active seismicity, the northeastern portion of the Adria microplate, where the south-directed thrusts of the Alpine system merge with the NW-SE transpressive regime of the External Dinarides. Measurements include the ongoing interseismic strain accumulation processes, including the peculiar observation of episodic disturbances and southward tilting in the three years preceding the 1976 Mw6.4 Friuli earthquake [4].<br><br>The channel systems of Karst hydrology, which undergo complete flooding and overpressure buildup in extremely short time spans (e.g. near-simultaneous flooding over a distance of 30 km) result in observable surface deformation and a change in the gravity field. Tilt time series allow to extract and model this type of hydrology-forced uplift and associated deformation [2,5].<br><br>Tilt- and strain-meters allow for accuracy and precision in measuring crustal deformation, to a level which space-borne geodesy cannot provide. The main drawback, however, is that only point measurements are provided, in locations where stations could be set up.<br>On the other hand, the thousands of points on the surface that DInSAR can provide are affected by coarser accuracy and influenced by atmospheric effects - resulting in LoS displacements uncorrelated to the actual surface deformations. We aim at enabling the transfer of knowledge from tilt- and strain-meters observations to DInSAR-derived data, thus allowing a first assessment of ground-truth constrained displacement models.<br><br>[1] Braitenberg C. (2018). The deforming and rotating Earth - A review of the 18th International Symposium on Geodynamics and Earth Tide, Trieste 2016 , Geodesy and Geodynamics, 187-196, doi::10.1016/j.geog.2018.03.003</p><p>[2] Braitenberg C., Pivetta T., Barbolla D. F., Gabrovsek F., Devoti R., Nagy I. (2019). Terrain uplift due to natural hydrologic overpressure in karstic conduits. Scientific Reports, 9:3934, 1-10, doi.:10.1038/s41598-019-38814-1</p><p>[3] Rossi, G., Fabris, P. & Zuliani, D. Overpressure and Fluid Diffusion Causing Non-hydrological Transient GNSS Displacements. Pure Appl. Geophys. 175, 1869–1888 (2018). https://doi.org/10.1007/s00024-017-1712-x</p><p>[4] Dragoni M., Bonafede M., and Boschi E. (1985). On the interpretation of slow ground deformation precursory to the 1976 Friuli earthquake. Pure and Applied Geophysics 122, 781–792. doi:10.1007/978-3-0348-6245-5_3</p><p>[5] Grillo B., Braitenberg C., Nagy I., Devoti R., Zuliani D., Fabris P. (2018). Cansiglio Karst-Plateau: 10 years of geodetic-hydrological observations in seismically active northeast Italy. Pure and Applied Geophysics, 175, 5, 1765-1781, doi:10.1007/s00024-018-1860-7.</p><p> </p>

Interactions of temperature fluctuations of the Pacific, Indian and Atlantic oceans with Global atmospheric oscillation

<p>The predictability of El Niño and La Niña is investigated. In this case, the recently discovered so-called Global Atmospheric Oscillation (GAO) is considered (Serykh et al., 2019). Assuming GAO to be the main mode of short-term climatic variability, this study defines an index that characterizes the dynamics and relationships of the extratropical components of the GAO and El Niño – Southern Oscillation (ENSO). Due to the general propagation of the GAO’s spatial structure from west to east, another index – predictor of ENSO is defined. The cross-wavelet analysis between both of these indices and the Oceanic Niño Index (ONI) is performed. This analysis reveals a range of timescales within which the closest relationship between the GAO and ONI takes place. Using this relationship, it is possible to predict El Niño and La Niña with a lead-time of approximately 12 months (Serykh and Sonechkin, 2020a).</p><p>Using data on the distribution of temperatures in the Pacific, Indian, and Atlantic Oceans, large-scale structures of spatial and temporal variations of these temperatures are investigated (Serykh and Sonechkin, 2020b). A structure is found which is almost identical to the spatial and temporal sea surface temperature (SST) structure that is characteristic of the GAO. Variations in water temperature in a near-equatorial zone of the Pacific Ocean at depths up to about 150 meters behave themselves in the same way as variations in sea surface height and SST. At even greater depths, variations in water temperature reveal a "striped" structure, which is, however, overall similar to that of SST variations. Variations of water temperature at depths in all three oceans spread from east to west along the equator with a period of 14 months. This makes it possible to think that the dynamics of these temperatures are controlled by the so-called Pole tides. The surface North Pacific Pole Tide was found previously responsible for excitation of El Niño (Serykh and Sonechkin, 2019). The deep Pole tides in the Southern Atlantic and Southern Indian Ocean appear to be triggers of the Atlantic El Niño and Indian Ocean Dipole (IOD). Thus, IOD manifests itself at the depth of the thermocline more clearly than on the surface of the Indian Ocean. The out-of-phase behavior of El Niño and IOD is explained by the 180-degree difference in the longitudes of these phenomena.</p><p> </p><p><strong>References</strong></p><p>Serykh I.V., Sonechkin D.M. Nonchaotic and globally synchronized short-term climatic variations and their origin // Theoretical and Applied Climatology. 2019. Vol. 137. No. 3-4. pp 2639–2656. https://doi.org/10.1007/s00704-018-02761-0</p><p>Serykh I.V., Sonechkin D.M., Byshev V.I., Neiman V.G., Romanov Yu.A. Global Atmospheric Oscillation: An Integrity of ENSO and Extratropical Teleconnections // Pure and Applied Geophysics. 2019. Vol. 176. pp 3737–3755. https://doi.org/10.1007/s00024-019-02182-8</p><p>Serykh I.V., Sonechkin D.M. El Niño forecasting based on the global atmospheric oscillation // International Journal of Climatology. 2020a. https://doi.org/10.1002/joc.6488</p><p>Serykh I.V., Sonechkin D.M. Interrelations between temperature variations in oceanic depths and the Global atmospheric oscillation // Pure and Applied Geophysics. 2020b. Vol. 177. pp 5951–5967. https://doi.org/10.1007/s00024-020-02615-9</p>

President's Page

Almost exactly 20 years ago, in July 2001, I organized and chaired the first SEG Summer Research Workshop on the topic of “Synergies in Geophysical, Medical and Space Imaging” (see The Leading Edge [TLE], 21, no. 6, 599-606). At the virtual SEG Annual Meeting in October 2020, special sessions were held on “Planetary Geophysics” and “Geophysics in Medicine.” Recently, I have been asked by SEG President Maurice Nessim to help lead two task forces to advance the use of applied geophysics in both the medical and space sciences. It is therefore an excellent time to share some thoughts on the next 20 years of collaboration possibilities in these areas.

The history of the Geophysical Service of Austria

A brief summary will be given of the historical development of Geophysical Service of Austria, which comprises the national geomagnetic, gravimetric and seismological services as well as the “Applied Geophysics Section” located at the Zentralanstalt für Meteorologie und Geodynamik (ZAMG) in Vienna in Austria. The paper presents the achievements, changes and challenges of the Department from its modest beginning in 1851 until 2020. Finally, a special emphasis is placed on the Conrad Observatory – one of the most comprehensive geophysical research observatories in the world.