This study aimed to investigate the performance of machine learning (ML) algorithms in determining horizontal velocity at specific points using the current Global Navigation Satellite System (GNSS) velocity field. To achieve this objective, the analysis utilized the most comprehensive velocity field available for Turkey, where 70% of the GNSS velocities was allocated for training the ML algorithms, while the remaining 30% was used for testing. Contrary to the previous research, the significance of considering the tectonic structure within the study area was emphasized at this point. To determine the tectonic structure of the horizontal velocity field in the region, a preliminary clustering procedure was conducted. Subsequently, distinct ML algorithms were trained using velocity fields associated with different tectonic plates. Moreover, to investigate the impact of the tectonic domain, the entire velocity field was also tested using ML algorithms without considering the tectonic structure. Four different ML algorithms, namely, Gradient Boosting Machines (GBM), LightGBM, Random Forest (RF), and eXtreme Gradient Boosting Machines (XGBoost), were employed to estimate the horizontal velocities (east and north components). The findings imply that incorporating the tectonic structure improved the performance of machine learning predictions, as indicated by the GBM algorithm's decreased root-mean-square error values. In addition, when the tectonic structure was taken into account, the accuracy assessment values for the RF and XGBoost algorithms in the east component decreased significantly. In terms of predicting GNSS velocities, the RF algorithm exhibited the lowest root-mean-square error values compared to other algorithms. The horizontal velocity differences between averages of the reference velocity field and the RF velocity estimates are maximum 0.4 mm/yr.

The spatiotemporal pattern of surface displacements from large earthquakes provides crucial insights about the deformation of Earth’s crust at various scales and the interactions among tectonic plates. However, the lack of extensive and large-scale geodetic networks near such seismic events hinders our thorough understanding of the large-scale crustal deformation resulting from earthquakes. Using Türkiye’s extensive and continuous global navigation satellite system (GNSS) network during the moment magnitude 7.8 and 7.6 Kahramanmaraş earthquakes on 6 February 2023, we show that large earthquakes can induce far-field crustal deformations (>700 kilometers), exceeding current predictions from elastic dislocation models. They can lead to the mobilization of tectonic plates and the triggering of far-field earthquakes, which carries profound implications for seismic hazard assessments and necessitates a new perspective on crustal deformation and earthquake mechanics.

Overview Measuring accurately the relative movement of the surface of the Earth is a critical constraint on the slow and broad tectonic loading and unloading to which faults respond, and is one of the few observations of the solid Earth that may be made directly without inference. High-precision geodetic observations, such as from Global Navigation Satellite Systems (GNSS), which includes the Global Positioning System (GPS), and interferometric synthetic aperture radar (InSAR), allow measurement of fault motions between, during and in the aftermath of earthquakes and other related tectonic phenomena, densely in both space and time. The Community Geodetic Model (CGM) provides velocities and time series of observed points on the Earth's surface over Southern California using data from a number of contributing researchers, institutions and analysis centers. The GNSS products provide high temporal resolution (nominally daily measurement points for continuous stations) in three dimensions at specific observation sites and the InSAR products provide high spatial resolution (approximately one point per tens of m on the ground, depending on exact specifications of data and processing). Combined, they provide the ability to study crustal deformation over a wide range of distances and periods. The CGM differs from other SCEC Community Models in that it is constantly extending with time as new data are acquired daily, so it is not static. The CGM version 1 (2016; doi:10.5281/zenodo.4926528) was a collection of time-independent (velocity-only) geodetic products gathered from published papers. The GNSS velocities were then combined and modeled by a Working Group researching methods and contributing interpolated deformation fields. The main goal of the CGM version 2 is to add time-dependent (time series) products to both the GNSS and InSAR products. For the GNSS, this is done by ingesting survey and (mostly) continuous time series from five analysis centers in the U.S.: the Geodetic Facility for the Advancement of Geoscience (GAGE); the Nevada Geodetic Laboratory (NGL) at the University of Nevada, Reno (UNR); the NASA Jet Propulsion Laboratory (JPL) and Scripps Orbital and Permanent Array Center (SOPAC) contributions to the MEaSUREs ESESES project; and the U.S. Geological Survey (USGS). Like the various contributions to the CGMv1 GNSS velocities, these time series are rigorously adjusted to be self-consistent, before a weighted mean is calculated to produce the consensus products. Much of the InSAR contribution is a consensus from research by the SCEC community within the CGM (InSAR) Working Group, whose individual contributions are listed below and in more detail in the README.txt file in the top directory of the archive. The CGMv2 is therefore a "union" or "superset" of survey and continuous GNSS and InSAR time series. Please see https://www.scec.org/research/cgm for more information. Version: CGMv2.0.0 This is the second major release of the CGM (version 2.0.0) and is distributed as a zip-file. See below and in the README.txt file for information about the directory structure and contents of the entire zipped archive. Much of the SCEC5 activity was focused on the assembly of GNSS and InSAR time series for measuring temporally variable motions, expanding the CGMv1 with the time dimension. The CGMv2.0.0 is a time-dependent set of products, consisting of time series and velocities of the Earth's surface measured by GNSS and InSAR. Directory Structure and Contents data/gnss/pos/The CGMv2.0.0 GNSS time series in "pos" format (plain text), relative to various reference frames described below. Header lines in each file provide information about the nominal reference coordinates and data columns. Files named "*.wmrss_*" are the continuous stations (weighted mean with rescaled sigma) and files named "*.final_" are the survey sites. data/gnss/pos/igb14/ The International GNSS Service's (IGS's) revised realization of ITRF2014 data/gnss/pos/nam14/ North America defined by Altamimi et al.'s (2017) ITRF2014 plate motion model data/gnss/pos/pcf14/ The Pacific defined by Altamimi et al.'s (2017) ITRF2014 plate motion model data/gnss/pos/nam17/ North America defined by Kreemer et al. (2018) data/gnss/vel/The CGMv2.0.0 GNSS velocities in a CSV file similar to GAGE's "vel" format (plain text), relative to the same reference frames described above. Header lines in each file provide information about the data columns. data/insar/The CGMv2.0.0 InSAR line-of-sight consensus time series and velocities for four ESA Sentinel-1 tracks (ascending tracks 64 and 166, and descending tracks 71 and 173) over Southern California, in an HDF5 format designed for the CGM. A description of and reader for the HDF5 files may be found here. data/insar/contrib/Individual contributions to the InSAR time series and velocity products, as described below and in more detail in the top-level README.txt file. Contributors The GNSS time series are a weighted mean, after restoration of global scale if processed using Gipsy (JPL, NGL/UNR and USGS) and self-consistent alignment of reference frame, of the following GNSS analysis centers, whose products are publicly available at the embedded hyperlinks: The Geodetic Facility for the Advancement of Geoscience (GAGE) (Herring et al., 2016) The Nevada Geodetic Laboratory at the University of Nevada, Reno (Blewitt et al., 2018) NASA's Jet Propulsion Laboratory contribution to the MEaSUREs ESESES Project SOPAC's contribution to the MEaSUREs ESESES Project The United States Geological Survey (Murray and Svarc, 2017) Zheng-Kang Shen's (UCLA) survey time series Z.-K. Shen processed the raw data from the SCEC survey-mode GPS data archive to provide the corresponding time series and velocities. A. Gonzalez Ortega provided processed time series from CICESE's REGNOM network of continuous GNSS stations. M. Floyd and T. Herring designed the download, alignment and combination of the publicly available continuous GNSS archives, listed above, in various reference frames. Contributions from individuals and institutions within the SCEC community to the CGM (InSAR) products are: K. Wang contributed time series and velocity solutions K. Guns and X. Xu contributed time series and velocity solutions Z. Liu contributed time series and velocity solutions S. Sangha, M. Govorcin and D. Bekaert contributed time series and velocity solutions G. Funning contributed time series and velocity solutions E. Tymofyeyeva calculated the combination of contributed solutions to generate the consensus product K. Materna contributed time series and velocity solutions, and wrote the translation tools for converting to and from HDF5 format, as designed by all InSAR contributors listed immediately above plus M. Floyd Three groups (K. Guns and X. Xu; Z. Liu; and S. Sangha, M. Govorcin and D. Bekaert) independently processed interferograms from common raw datasets using different processing approaches. E. Tymofyeyeva coordinated and led the InSAR Working Group. M. Floyd coordinated and led the wider CGM Working Group. All contributed to the design of the HDF5 format in which the InSAR products are distributed.

SUMMARY The Global Positioning System (GPS), although it has existed for only 30 years, is an important source for active tectonics, resulting in estimates of plate motions very close to geologic estimates over millions of years. GPS is also used for elastic block models to calculate slip rates for a better understanding of Earth’s active crustal deformation. GPS-derived velocity fields may be used as the basis for clustering analysis to create a preliminary definition of block geometry. In this study, we used published horizontal velocity fields to evaluate the effects of data dependences on determining the optimum number of clusters with algorithms. For this purpose, we used different variations of velocity fields in Turkey and tested four different algorithms that are Davies–Bouldin index, the elbow method, GAP statistics algorithm and the silhouette method. We also clustered velocity components with the k-means technique and compared the results with previous studies.

GNSS observations in and around the Aegean Sea, Peloponnese, and western Turkey are sufficiently precise and densely spaced to provide an image of the deformation associated with the Hellenic subduction zone. To isolate deformation associated with the plate boundary, we use GNSS secular velocities and shallow earthquake locations to determine an upper plate reference frame with low internal deformation (<2 mm/yr) that includes a large area of the central and western Aegean. We interpret upper plate deformation as resulting from stronger coupling on the subduction plate interface beneath western Crete than on the western or eastern segments of the Hellenic subduction zone, and the geometry of the subducting plate along-strike. If the long-term tectonic extension of the Aegean upper plate counteracts some of the contractional deformation signal from elastic strain accumulation on the subduction interface, as measured at the surface, the coupling coefficient may be as high as 40% around western Crete, although this is the upper limit.

We present a broad view of present-day motions and deformations derived from uniform processing of GNSS observations within the Nubia-Arabia-Eurasia zone of plate interaction. The new observations we present provide a similar to 29% increase in the number of velocity determinations, a reduction in average station spacing from similar to 76 km to similar to 39 km, and an improvement in velocity uncertainties (for <1 mm/year), from 180 to 578 sites compared to our prior published solution (Reilinger et al., 2006). We use these new constraints to better evaluate the role of faults and blocks in controlling the character of continental deformation within the zone of plate interactions. Simple elastic block models show that internal deformation of the region occurs in large part on mapped, seismically active fault systems, indicating elastic behavior of the seismogenic crust (above similar to 15 km). For example, eastern central Anatolia, an area of > similar to 126,000 km(2), bounded by the North and East Anatolian Faults exhibits internal velocity differences of <0.5 mm/year, indicating strain rates of < similar to 1.5 nanostrain/year. Geodetically constrained fault slip rates obtained from this simplified approach are comparable to geologic rates, indicating that major faults have controlled the recent geologic evolution of the region (i.e. 5-10 Myr). The pattern of present-day deformation, including increasingly fast motions towards the Hellenic trench, and the roughly simultaneous opening of all the major Mediterranean basins in the early Miocene with the slowing of the Nubia-Eurasia convergence, support conceptual models that foundering and rollback of the subducted Nubian slab beneath the Aegean is the primary mechanism responsible for present-day motion and internal deformation of the Anatolian-Aegean region.

The East Anatolian Fault (EAF) is a left‐lateral transform fault accommodating the relative motion between the Anatolian and Arabian plates. On January 24, 2020, Mw6.8 Sivrice (Elazığ) earthquake is the largest event that occurred along the EAF since the nineteenth century. The earthquake provides a unique opportunity to capture a critical stage of the seismic cycle from the interseismic deformation to co‐seismic rupture. In this study, we examine the relationship between the interseismic fault activity and co‐seismic behavior of the earthquake. A kinematic model of the earthquake obtained from strong‐motion, GNSS and teleseismic waveforms along with static displacements from GNSS and InSAR data shows that the mainshock ruptured only 45 km of the 95 km long Sivrice‐Pütürge segment. Rupture initiated adjacent to the interseismically weakly coupled northeastern section and propagated unilaterally toward southwest with a rupture velocity of ∼2.5 km/s, stopping ∼30 km before the southwestern segment boundary. The earthquake did not generate any surface offsets. We identified 4 long‐term near‐repeating earthquake clusters beneath the highest co‐seismic slip zone adjacent to the northeastern creeping section. The mainshock was dynamically triggered by a M ∼ 5.4 foreshock located within the zone of near‐repeating earthquakes. We suggest that creep along the weakly coupled section of the fault loaded the neighboring locked section leading to the repeating earthquakes below the locked zone. The earthquake partially ruptured a fault segment characterized by high rate of diffuse seismicity, structural complexities and heterogeneous coupling, leading to a source characterized by a complex source time function with relatively slow rupture velocity.

Southern Africa is typically considered to belong to a single tectonic plate, Nubia, despite active faulting along the southwestern branch of the East African Rift System. We analyze regional Global Navigation Satellite System (GNSS) measurements, and find that the “San” microplate, situated south of the southwestern branch of the East African Rift, is statistically distinct from Nubia, with 0.4–0.7 mm/yr of extension across the boundary. Adding nine new campaign GNSS sites, we show that the extension rate across the southern Malawi Rift is 2.2 ± 0.3 mm/yr, with 75% of the relative velocity occurring over 890 km, despite the surface expression of faulting being <150 km wide. Thus, for the first time, we use geodetic measurements to describe the accommodation of strain in broad zones between Archean cratons in southern Africa's thick continental lithosphere.

A seismic gap along the western segment of the North Anatolian Fault, in the Marmara-Izmit region, was identified before the 1999 M7.6, Izmit and M7.4 Duzce earthquakes, so the region along the coseismic fault has been monitored with geodetic techniques for decades, providing well defined pre-, co- and post-seismic deformations. Here, we report new continuous and survey GPS measurements with near-fault (~2 – 10 km to the fault) and far-fault (~50 – 70 km from the fault) stations, including 7 years (2013 – 2019) of continuous observations, and 5 near-fault campaigns (every six months between 2014 – 2016) to further investigate postseismic deformation. GPS observations were processed with the GAMIT/GLOBK (v10.7) GNSS software. We used these observations to estimate the spatial distribution of current aseismic after-slip, along the 1999 Izmit rupture. We also searched for spatiotemporal changes of shallow creep events along the surface trace. With elastic models and GPS observations, we determined a shallow creep rate that reaches a maximum around the epicenter of the 1999 Izmit earthquake of about 12.7 ± 1.2 mm/yr, consistent with published InSAR results. Creep rates decrease both east and west of the epicentral region. Moreover, we show that broad-scale postseismic effects that diminish logarithmically, continue at present. (This study is supported by TUBITAK 1001 project no: 113Y102 and 117Y278)

The M-w 6.4 and M-w 7.1 Ridgecrest, California, earthquakes of July 2019 occurred within 34 hr of each other on conjugate strike-slip faults in the Mojave Desert, just north of the central Garlock fault. Here, we present the results of a survey of 18 Global Navigation Satellite Systems (GNSS) sites conducted in the immediate aftermath of the earth- quakes, including five sites that recorded the motion of the second earthquake after having been set up immediately following the first, as well as processed results from continuous GNSS sites throughout the region. Our field work in response to the earthquakes provides additional constraints on the ground displacement due to both earthquakes, complementing data from a spatially sparser network of continuously recording GNSS sites in the area, as well as temporally sparser Interferometric Synthetic Aperture Radar data that were able to capture a combined deformation signal from the two earthquakes.

Being a part of ongoing continental collision between the Arabian and Eurasian plates, the Caucasus region is a remarkable site of moderate to strong seismicity, where devastating earthquakes caused significant losses of lives and livelihood. In this article, we survey geology and geodynamics of the Caucasus and its surroundings; magmatism and heat flow; active tectonics and tectonic stresses caused by the collision and shortening; gravity and density models; and overview recent geodetic studies related to regional movements. The tectonic development of the Caucasus region in the Mesozoic-Cenozoic times as well as the underlying dynamics controlling its development are complicated processes. It is clear that the collision is responsible for a topographic uplift / inversion and for the formation of the fold-and-thrust belts of the Greater and Lesser Caucasus. Tectonic deformations in the region is influenced by the wedge-shaped rigid Arabian block indenting into the relatively mobile region and producing near N-S compressional stress and seismicity in the Caucasus. Regional seismicity is analysed with an attention to sub-crustal seismicity under the northern foothills of the Greater Caucasus, which origin is unclear – whether the seismicity associated with a descending oceanic crust or thinned continental crust. Recent seismic tomography studies are in favour of the detachment of a lithospheric root beneath the Lesser and Greater Caucasus. The knowledge of geodynamics, seismicity, and stress regime in the Caucasus region assists in an assessment of seismic hazard and risk. We look finally at existing gaps in the current knowledge and identify the problems, which may improve our understanding of the regional evolution, active tectonics, geodynamics, shallow and deeper seismicity, and surface manifestations of the lithosphere dynamics. Among the gaps are those related to uncertainties in regional geodynamic and tectonic evolution (e.g., continental collision and associated shortening and exhumation, lithosphere structure, deformation and strain-stress partitioning) and to the lack of comprehensive datasets (e.g., regional seismic catalogues, seismic, gravity and geodetic surveys).

We present fast algorithms for estimating common parameters in geodetic time series based on statistical approaches to assess the impact of temporal correlations. One such assessment is based on the characteristics of the time series residuals averaged over different durations and with the statistical characteristics extrapolated with a first-order Gauss-Markov process to infinite averaging time. This approach circumvents a limitation of spectral methods, which cannot reliably account for the impact of temporal correlations over periods longer than the length of a given time series. The subsequent fast approach is the use of a Kalman filter with process noise values determined from the first-order Gauss-Markov characteristics to estimate all parameters. These methods are particularly useful for assessing long and numerous geodetic time series, which are nowadays ubiquitous, because they are much less computationally intensive than comprehensive methods, such as maximum likelihood estimators. Our approaches are compared to other commonly used programs, such as Hector, to understand the speed and impact of outliers on the algorithms, and to provide advice and suggestions on the uses of such algorithms in operational geodetic processing.

SUMMARYIn order to better assess earthquake hazards, it is vital to have a better understanding of the spatial and temporal characteristics of fault creep that occur on ruptured faults during the period following major earthquakes. Towards this end, we use new far-field GPS velocities from continuous stations (extending ∼50–70 km from the fault) and updated near-fault GPS survey observations, with high temporal and spatial density, to constrain active deformation along the Mw7.4, 1999 Izmit, Turkey Earthquake fault. We interpret and model deformation as resulting from post-seismic afterslip on the coseismic fault. In the broadest sense, our results demonstrate that logarithmically decaying post-seismic afterslip continues at a significant level 20 yr following 1999 Earthquake. Elastic models indicate substantially shallower apparent locking depths at present than prior to the 1999 Earthquake, consistent with continuing afterslip on the coseismic fault at depth. High-density, near-fault GPS observations indicate shallow creep on the upper 1–2 km of the coseismic fault, with variable rates, the highest and most clearly defined of which reach ∼12 mm yr−1 (10–15 mm yr−1, 95 per cent c.i.) near the epicentre between 2014–2016. This amounts to ∼half the long-term slip deficit rate.

SUMMARY The present-day tectonics of the southern Red Sea region is complicated by the presence of the overlapping Afar and southern Red Sea rifts as well as the uncertain kinematics and extent of the Danakil block in between. Here we combine up to 16 yr of GPS observations and show that the coherent rotation of the Danakil block is well described by a Danakil-Nubia Euler pole at 16.36°N, 39.96°E with a rotation rate of 2.83 deg Myr–1. The kinematic block modeling also indicates that the Danakil block is significantly smaller than previously suggested, extending only to Hanish-Zukur Islands (∼13.8°N) with the area to the south of the islands being a part of the Arabian Plate. In addition, the GPS velocity field reveals a wide inter-rifting deformation zone across the northern Danakil-Afar rift with ∼5.6 mm yr–1 of east–west opening across Gulf of Zula in Eritrea. Together the results redefine some of the plate boundaries in the region and show how the extension in the southern Red Sea gradually moves over to the Danakil-Afar rift.

Ion temperature is a key parameter that influences dynamics in the magnetosphere, such as particle transport and wave‐particle interactions. Measurements of ion heating and energization yield information about phenomena such as magnetic reconnection, bursty bulk flows, and ion injections. Taking advantage of the global view provided by energetic neutral atom imaging, a database of ion temperature maps during geomagnetic storms occurring throughout the National Aeronautics and Space Administration (NASA) Two Wide‐angle Imaging Neutral atom Spectrometers (TWINS) mission has been created. These ion temperature maps and relevant metadata are publicly available on CDAWeb to facilitate comparison to in situ measurements and model output, for use as boundary conditions for simulations, and for other relevant studies. A preliminary study of average plasma sheet ion temperatures calculated from these maps has revealed a common occurrence of decreasing ion temperature, and a case study for one storm is presented.

Geodetic observations in the Turkana Depression of southern Ethiopia and northern Kenya constrain the kinematic relay of extension from a single rift in Ethiopia to parallel rifts in Kenya and Uganda. Global Position System stations in the region record approximately 4.7 mm/year of total eastward extension, consistent with the ITRE14 Euler pole for Nubia -Somalia angular velocity. Extension is partitioned into high strain rates on localized structures and lower strain rates in areas of elevated topography, as across the Ethiopian Plateau. Where high topography is absent, extension is relayed between the Main Ethiopian Rift and the Eastern Rift across the Turkana Depression exclusively through localized extension on and immediately east of Lake Turkana (up to 0.2 microstrain/year across Lake Turkana). The observed scaling and location of active extension in the Turkana Depression are inconsistent with mechanical models predicting distributed stretching due to either inherited lithospheric weakness or reactivated structures oblique to the present-day extension direction. Plain Language Summary The continent of Africa is breaking up into multiple pieces. This divergence is accommodated through extension along the East African Rift System. The Turkana Depression, which lies on the border of Ethiopia and Kenya, is of interest due to its previous rifting episodes, low elevation compared to the surrounding rift system, and location linking more prominent rift valleys to the north and south. Global Position System observations of surface velocities show that extension in the Turkana Depression is confined to a narrow region, not distributed across a broad area. These results suggest the East African Rift System is accommodating the breakup of the African continent through a combination of distributed deformation in areas with high topography and localized extension across low elevation rift basins.

The Geysers geothermal field in northern California has seen subsidence, attributed to net volume loss during power production, since at least the 1960s. Over the last three decades this has been accompanied by reductions in reservoir steam pressure and power generation. To combat these effects, wastewater has been injected in the field since 1997. In order to better understand the effects of variations in production and wastewater injection on geothermal reservoir volume and surface subsidence over time, we installed two continuously-recording GPS stations (TG01 and TG02) in the northern Geysers in 2012 and one in the southern Geysers (TG03) in 2013. We present here our first analyses of the continuous GPS data. Combining these data with data from seven PBO GPS stations in the region, we first use common-mode filtering to remove any regionally-correlated seasonal noise from our GPS time series. Both TG01 and TG02 show early periods of uplift and later subsidence while TG03 shows ongoing subsidence. Next, we downsample steam extraction and injection data onto a rectangular grid and calculate ‘observed’ monthly volume changes as a function of position. We then use these to drive a forward elastic dislocation model to predict surface deformation changes each month in The Geysers field. This forward model overpredicts subsidence at all three Geysers GPS locations. We then compare the observed volume changes with inverse elastic dislocation models of the volume changes required to reproduce the GPS time series. We find that our GPS data do not have sufficient spatial resolution to reproduce the variability in reservoir volume change from reported well data. However, the estimates of total volume change from the inverse models and

Author(s): Funning, Gareth J; Brooks, Benjamin; Fialko, Yuri; Floyd, Michael; Haase, Jennifer; Hammond, William; Sandwell, David T; Svarc, Jerry; Xu, Xiaohua