Geodetic Science Snapshots - All Topics

Geodetic stations at two coastal sites in Hong Kong were able to measure storm surge from Typhoon Hato in 2017 and Typhoon Mangkhut in 2018, using GNSS Interferometric Reflectometry (GNSS-IR). Adding more satellite signals and GNSS ground stations would provide greater coverage in space and time and greater accuracy to geodetic, storm-resistant, ground-based measurements of sea level, storm surge and even tsunami height.

GNSS observations show surface horizontal displacements of 4 to 8 millimeters wobbling back and forth for more than five months and over thousands of kilometers before massive subduction zone earthquakes in Japan and Chile. Detailed modeling of the dense geodetic data for the Japan earthquake suggests a fluid-triggered slab pull helping to initiate a massive event.

A new method to measure relative sea-level rise in low-elevation coastal zones combines global navigation satellite system (GNSS) data with measurements from rod surface-elevation table–marker horizons (RSET-MHs) and satellite altimetry. Combining these measurements shows that the sediments in coastal Louisiana are subsiding faster than previously recognized and thus relative sea level is rising at a higher rate.

A stable Caribbean reference frame 2018 (CARIB18) is developed for the Caribbean plate using long-term observations from 18 GPS stations along the margins of the plate. The results provide seven parameters for transforming positional time series from a global reference frame (IGS14) to a regional reference frame. CARIB18 is fundamental to study plate motions and other earth processes.

A new way to measure seafloor motions with Global Positioning System (GPS) in shallow seas is tested in Tampa Bay, Florida. Observations over many months indicate seafloor motions in three dimensions can be measured. The method can be applied for offshore oil operations, lakes around volcanic edifices, shallow submarine regions near the coasts that are above active subduction zones and for other applications.

Extensive geologic and geodetic data, especially terrestrial LiDAR and GPS, help decipher the dynamics of the eastern Basin and Range in the Sevier Desert, Utah. Over the past 30,000 years, the extension rates on faults near the Basin and Range-Colorado Plateau Transition Zone are much higher than in the Basin and Range. In the Sevier Desert, these high rates are due to periods of volcanism that caused magma-assisted rifting to activate these faults.

A novel combination of ground penetrating radar and terrestrial LiDAR scanning provides details about the state of seasonal snowpack in Colorado without destroying the snow layers. Testing shows high variability in volumetric liquid water contents. The rapid changes in the amount of liquid water occurred in small areas over short time periods. Understanding the state of a snowpack is important for managing water resources.

Global Navigation Satellite Systems (GNSS) networks in the Americas provide useful observations of Earth processes and help with earthquake, volcano, tsunami and other hazard preparedness, response and mitigation. The networks consist of thousands of ground-based sites that provide high precision measurements of Earth motions and atmospheric conditions, in real time or through daily download.

High-rate GPS observations over long time periods after an earthquake were compiled to resolve weaker ground motions from large events. Analysis of long duration GPS signals for the 2011 Tohoku-Oki earthquake from the Plate Boundary Observatory (PBO) network in the contiguous western U.S. identifies multiple shear wave reflections and surface waves that traverse the globe multiple times. This analysis opens up a significant new way to understand the structure of the upper mantle using geodesy.

The July 2019 moment magnitude 6.4 and 7.1 Ridgecrest California earthquakes occurred about 34 hours apart on connected strike-slip faults. Continuous and temporary Global Navigation Satellite Systems (GNSS) sites captured the surface motions during and after the events. The data provides crucial information about how the faults move during and after an earthquake and how this motion is related to other processes, such as plate tectonics and fault creep.

An 86-floor tall, steel-sculpted concrete building in Kuwait was shaken by a moment magnitude 7.3 earthquake far away at the Iran-Iraq border. The building’s shaking was captured by GPS sites, on the top of the building, and others near ground level. The ground shook with amplitudes of about 40 millimeters while the building shook up to 160 millimeters. Such observations can help to understand a building’s response to an earthquake and to improve building design in response to large stresses.

A global model of observed plate motions on Earth’s surface is developed using 19,664 interseismic GPS velocities for 307 distinct plates. The result shows that 50% of the world’s population lives within 200 kilometers of a fault with a slip rate of greater than 2 millimeters per year.

Synthetic Aperture Radar imagery and precipitation data of the Mud Creek landslide in California over 8 years, reveal the catastrophic failure was caused by a large increase in pore-fluid pressure. Satellite imagery is an effective tool for observing landslide behavior.

GPS data and modeling provides the angular velocities for eight blocks and shows that three of the blocks are deforming internally. The model suggests little locking of the Middle America subduction zone, a rheologically weak volcanic arc, and a Central America forearc sliver that moves slowly.

GPS time series and deformation modeling show that the Aira and Kirishima volcanoes are connected at depth. Geodetic observations can be used to determine the structure of volcanoes below the surface and help with hazard preparedness and response.

GPS measurements of surface motion near four dams in India, show that the surface moves when the water volume of the dam changes. These observations show that the water volume of the dam affects the stress of the surrounding rock. Thus the dams may contribute to stress changes and deformation, particularly triggering earthquakes nearby.

Ground displacements caused by wastewater injection near Cushing, Oklahoma determined from remote sensing showed between 4 to 6 centimeters of uplift across Cushing over 17 months. Remote sensing provides a significant new way to understand near-surface deformation caused by humans or nature, especially near critical infrastructure such as the Cushing Hub, among the largest of oil storage facilities.

The National Earthquake Information Center (NEIC) is responsible for responding to earthquakes around the world. The expansion of Earth imaging satellites has expanded capabilities for geodetic observations and satellite imagery to describe earthquakes and their impacts. NEIC can integrate satellite imagery into earthquake information products for public awareness.

Vertical surface motions measured by GPS sites in Idaho, Montana, Nevada and Wyoming can be combined to measure water load over local to regional scales that is useful for water resource management and our understanding of the water cycle. Users can use this technique and the many available geodetic networks to track precipitation, water quantity changes, and the state of aquifers.

California’s crustal motions due to plate tectonics, earthquakes, volcanoes, water, humans and other factors occur across many time and space scales. Utilizing geodetic observations over decades, a geodynamic model of these motions explores the cause and effect of past movements, creates a current dynamic model and incorporates the influence of new motions as they occur.

Utilizing 111 geodetic slip distributions for 73 earthquakes with magnitudes from 5.3 to 9.1, fault characteristics are correlated with magnitude. Geodetic data provides a different method to build or enhance empirical relations between magnitude and slip characteristics to improve our understanding of earthquake processes and enhance rapid assessment of earthquake risks and responses.

Analysis of source time functions and geodetic data show that within the first 20 seconds of a magnitude 7+ earthquake, the magnitude can be determined base on the characteristics of the slip pulse. This is a change from previous work regarding determinism or self-similar models of earthquakes. Beyond understanding earthquakes better, the results can help to more quickly determine the size of the event and help with preparedness, response and mitigation.

Examination of borehole strainmeter data for medium size earthquakes (magnitude 4 to 5) in California shows a postseismic moment that is intermediate between small and large earthquakes. This suggests there is a size dependence on the dynamics of earthquakes or on the properties of the fault area around the earthquakes.

A magnitude 7.9 earthquake on 23 January 2018 in the Gulf of Alaska broke multiple orthogonal fault segments. The GNSS data of ground deformation during and after the earthquake showed most of the slip on two west-southwest oriented faults. The earthquake does not appear to have increased the stress in the region of the magnitude 9.2 1964 Alaska earthquake.

Global Navigation Satellite Systems (GNSS) networks have been established and enhanced to provide information and warning about large earthquakes and tsunamis. The Centro Sismológico Nacional (CSN) of the Universidad de Chile can collect information about an earthquake and potential tsunami from GNSS data within seconds and provide early warning to communities in Chile and the rest of the world.

The 21 August 2017 total solar eclipse across the United States blocked solar radiation and influenced the ionosphere and the rest of the atmosphere. The total electron content (TEC) in the ionosphere was measured with UNAVCO’s network of U.S. Global Positioning System (GPS)/ Global Navigation Satellite System (GNSS) ground-based sites and other geodetic sites across the country.

A colluvial hollow in Fourmile Canyon, Colorado that was present after the 2010 Fourmile Canyon wildfire transitioned to a fluvial channel with steps and pools while retaining the original hollow roughness after an intense 2013 flood. The changes were measured with a terrestrial laser scanner from UNAVCO and can help understand future risks in a changing landscape.

The freeze-thaw dynamics of permafrost on the north slope of Alaska was measured over 12 years using a Global Navigation Satellite System (GNSS) site permanently embedded in the permafrost near Barrow, Alaska. The data reveal subsidence due to thawing each summer plus interannual variations. The technique provides a new spatial and temporal approach to quantify permafrost changes and it can be applied at more than 200 GNSS sites in cold regions.

Real-time Global Navigation Satellite System (GNSS) ground-based sites can measure displacements on the Earth’s surface. Here, the benefits of including GNSS in an earthquake early warning system are outlined and three different algorithms for integrating geodetic data into the USGS’s ShakeAlert system are identified.

GPS measurements in the Amundsen Sea Embayment show a rapid rise of as much as 41 millimeters per year. One reason for the rapid rise is a softer, more pliant mantle beneath the land surface. This may have implications for global sea level change forecasts.

Analysis of thousands of GPS observations over decades shows the upward bending of the stable North American plate due to ice loss and horizontal contraction, mostly due to higher than expected inward velocities around the edges of the former ice sheets.

The health of wild vegetation during the California drought of 2012 to 2014 was measured with reflected Global Positioning System (GPS) measurements from hundreds of sites that are part of the EarthScope Plate Boundary Observatory. The geodetic data is compared to optical-wavelength measurements at collocated sites. These methods can help gauge future conditions and inform environmental impacts on humans and nature.

Ground-based GNSS sites can measure the extent of sea ice. The method relies on measuring the signal to noise ratio of the satellite signal that reflects off of the ice. A single GNSS site, GTGU, situated on the coast of a bay at the Onsala Space Observatory, Sweden, measured sea ice extent over a three-year period.

Satellite and GNSS observations show that parts of the San Francisco Bay area are underlain by artificial fill and old mud deposits that are undergoing subsidence at a higher rate than previously appreciated. Combining the rate of subsidence with the potential sea level rise suggests that much more of the bay area could be inundated with water.

Snow accumulation along the Mercer and Whillans ice streams in West Antarctica was measured between 2007 and 2017 with an array of Global Positioning System (GPS) stations. The snow was measured using the signals from GPS satellites that reflect off of the snow surface into the bottom of the station antenna; an innovative and cost-effective method called GPS interferometric reflectometry (GPS-IR).

A crustal deformation model for the Western United States fits geodetic and geologic observations and shows where major changes in the crust are occurring. Such modeling is critical for earthquake hazard assessments and for understanding Earth processes.

The Global Positioning System (GPS) constellation can be used to detect dark matter. Sixteen years of ground-based GPS receiver observations were utilized to look for dark matter passing near Earth. Although no dark matter was detected, the results refine the properties of the universe, the accuracies of atomic clocks and future searches for dark matter.

Central America faces tsunami threats along the Pacific and Caribbean coasts and at the shores of large lakes. Large earthquakes caused the most damaging tsunamis, however, landslides or volcanic eruptions can cause tsunamis around large lakes. Warning systems rely on seismic and geodetic observations. The Central American Tsunami Advisory Center (CATAC) will use these observations to help reduce losses.

Analysis of past earthquakes shows that GPS/GNSS sites can provide high-rate, low-noise data to determine peak ground velocities for earthquakes of magnitude greater than 5.8. The geodetic-derived ground motion can help with earthquake early warning, emergency response and earthquake engineering.

Two coronal mass ejections impacted the Earth in February 2014 creating disturbances in the Arctic ionosphere. Multiple instruments measured the disturbances, particularly the Greenland GPS network (GNET). Analysis shows the solar inputs heated the polar atmosphere causing an upwelling of nitrogen-rich air that altered the normal ionospheric dynamics.

GPS sites in California measure the changing water load due to rainfall, snowfall, groundwater, and drought. The vertical motions are shown to influence the state of stress on shallow faults. The rise and fall of the surface due to water loading and unloading creates a small amount of additional stress on the faults and can trigger small earthquakes.

An analysis of the 2016 Iniskin earthquake shows how GPS sites in Alaska may augment earthquake early warning. For a large magnitude earthquake that originates at a shallow depth, information from GPS can provide some warning before the shaking arrives in populated areas such as Anchorage. The geodetic data can rapidly and precisely define the earthquake properties to help with response and triggered hazards such as landslides and tsunamis.

Greenland’s ice and snow mass has been melting at an accelerated rate for many years. A network of GNSS sites, set-up on coastal bedrock, has been utilized to measure a huge outflow of ice and water in 2012 and 2010 from the Rink Glacier. The horizontal motion at the GNSS site captures a solitary mass transport wave traveling coastward down the glacier in the summers of those two melt years.

The Mosul Dam on the Tigris River in Iraq was built on weak rock that is dissolving due to water infiltration since it was built. Satellite imagery shows the dam subsiding over 6 years. The subsidence increases the risk of dam failure, which would affect more than a million people living nearby and everyone who relies on the dam for energy and water.

A moment magnitude 7.8 earthquake ruptured a major subduction zone boundary between the Nazca and the South American plates just offshore of Ecuador on 16 April 2016. Synthetic aperture radar (SAR) data and model analysis show about 2.5 meters of slip at about 20 kilometers depth. The event implies shorter recurrence times for earthquakes in the region.

Groundwater withdrawal during the 2007 to 2010 drought in the San Joaquin Valley in California caused a great deal of subsidence. Geodetic, water level and geologic data were used to determine the amount of inelastic deformation. The results suggest that most of the deformation was inelastic during the drought and thus the volume of the aquifer has been reduced, leaving less storage capacity for water in the future.

An analysis of borehole strainmeter data from Plate Boundary Observatory sites in the western United States for 144 earthquakes from 2004 to 2014 reveals correlations between the peak strain from these events with distance from the hypocenter and the earthquake magnitude.

A new method to compute total electron content (TEC) in the ionosphere to measure perturbations caused by tsunami waves has been shown to work retrospectively for tracking tsunami waves around Hawaii from the 2012 Haida Gwaii, British Columbia M7.8 earthquake.

If you want to know everything about the methods and data analysis centers for GPS networks in North America and the Caribbean, this is the review you should read. The review describes methods for determining position time series, velocities and other parameters from 2170 stations.

Analysis of 35 rapid tremor reversals (RTRs) captured by two Plate Boundary Observatory borehole strainmeters near Vancouver Island, British Columbia shows these subevents have high slip rates and modest strain energy release. RTRs contribute a significant fraction of the slow slip moment.

Using GPS and Sentinel 1 radar imagery, the slip along the West Napa fault zone (WNFZ) during and after the 2014 South Napa earthquake was measured. The complexity of the slip and afterslip suggests that hard rock and soft sediment heterogeneity control the style of friction on the fault plane.

Combining geodetic and seismic observations can reduce the amount of time needed to assess the tsunami intensity generated by a large magnitude thrust fault earthquake along a subduction zone. Through retrospective analysis of four tsunamigenic large earthquakes in Japan and Chile, the tsunami potential at the local coast was estimated within less than 2 minutes.

Long-term records from GPS stations along the Atlantic Coast of North America show long term subsidence due to geologic adjustments and short term subsidence due to human-related groundwater extraction. These measurements are critical for understanding water use, sediment structure and sea level rise.

A network of GPS stations measures atmospheric water vapor over the continental United States. The data tracks annual and seasonal moisture transport from the Gulf of Mexico into the Great Plains and the moisture variability related to the North American monsoon. These measurements are valuable for severe weather forecasts.

The Mw 6.0 South Napa earthquake created measurable surface rupture over about 12 kilometers on several active strands of the West Napa fault zone (WNFZ). Field observations and airborne and satellite-based imagery show earthquake deformation and post-earthquake deformation. The complex fault rupture and post-earthquake fault slip has implications for estimating earthquake hazards.

Global Positioning System (GPS) measurements of the uplift of the ground surface beneath the Greenland ice sheet is critical to determining the amount of ice mass that has been lost since the Last Glacial Maximum (LGM). The GPS data show larger uplift rates than previously recognized and suggest that satellite studies have underestimated the ice mass loss by about 20 gigatons per year or about 1.5 meters of sea level rise since the LGM.

The San Andreas Fault System (SAFS) has been captured flexing between large earthquakes in southern California with EarthScope’s Plate Boundary Observatory (PBO). The flexure is related to 300 years of fault locking and creeping at different fault depths. Quantifying the flexure will improve estimates of seismic hazard.

Ground-based GPS measurements of the total electron content (TEC) in the ionosphere show discrepancies compared to a global model and suggest that there is a larger difference between the solar flux measured via radio emissions and the extreme ultraviolet flux coming from the Sun.

The addition of geodetic data into the Pacific Northwest Seismic Network earthquake early warning system shows important enhancement to the warning system. Tests show the Geodetic First Approximation of Size and Time (G-FAST) could determine the characteristics of the 2001 Mw 6.8 Nisqually earthquake with sufficient robustness to warn communities at risk.

Estimates of the probabilities of a magnitude greater than 9.0 earthquake for the Aleutian Islands are about 6.5 to 12 percent over the next 50 years. Such an event poses obvious earthquake and tsunami risks for Alaska and tsunami risks for western North America and Hawaii.

The 7 November 2012 moment magnitude 7.4 Champerico (Guatemala) earthquake is among a growing number of subduction zone events observed by a local geodetic network. The GPS data show up to 2 meters of slip over a 30 by 30 square kilometer area on the fault at a depth of 10 to 30 kilometers. The data refine the location of the earthquake, increasing our understanding of faults and plate motions as well as earthquake risk resiliency.

In Palmer Land, in the southern Antarctic Peninsula, the pattern of deformation measured by a dense network of GPS receivers cannot be explained by our current understanding of ice sheet change across the region. In particular, the GPS measurements indicate that either there was more ice in this region in the past, or ice retreat in the southwestern Weddell Sea region continued until much more recently than previously thought.

High rate GPS network measurements combined with accelerometer and satellite radar data show that the 25 April 2015 magnitude 7.8 Gorkha Nepal earthquake ruptured a 20-kilometer wide segment of the fault at depth. The rupture propagated toward the Kathmandu basin and the smooth slip onset caused only moderate ground shaking in the city. Greater damage, especially to taller structures in Kathmandu, was caused by whole basin resonance of the seismic waves.

Combined analysis of the seismic and bathymetric data collected along the Aleutian arch of Alaska near Chirikof Island shows a splay fault beneath a subducted ridge. These features suggest the possibility of a earthquake causing a large tsunami that could be directed toward the west coast of the contiguous U.S.. Significantly, the GPS data from Chirikof Island shows that the fault is 90% locked, such that failure in a large earthquake is possible.

Using years of data from the dense geodetic and seismic networks in Japan, researchers find that slow slip events that repeat either coincide or precede large magnitude earthquakes along the major subduction zone off the coast of northeastern Japan.

GPS sensors record the motion of the Helheim Glacier in Greenland as ice calving occurs at its terminus. As the iceberg rotates and rolls off sideways, the glacier springs backwards and moves downwards. This action produces an earthquake and the GPS sensors record all the motion and help to explain how glacial earthquakes occur.

GPS data combined with Interferometric Synthetic Aperture Radar (InSAR) images characterize the fault and slip distribution for the 24 August 2014 M 6.0 South Napa earthquake. These results show the utility of geodetic data for rapid earthquake response, especially in areas where teleseismic data may not constrain the complexities of damaging events.

Airborne and terrestrial Lidar data of volcanic interior systems in the about 4 million year old San Rafael volcanic field in Utah details 7 sill forming events and 12 conduit forming events. The large volume of shallow sills show that these structures are important for eruption dynamics and inform studies of active volcanoes, particularly their patterns of unrest.

The active plate boundary marked by the Zagros Mountains has high seismicity, a complex fold and fault system and significant hydrocarbon reserves. Analysis of the 18 August 2014 Mw 6.2 Mormori, Iran earthquake with synthetic aperture radar (SAR) satellite imagery shows the event occurred along a shallow, blind thrust fault in the softer sediments above firmer bedrock.

An analysis of geodetic and airborne UAVSAR imagery related to the 2014 M5.1 La Habra earthquake shows that the Los Angeles metro area consists of a complex system of shallow faults that tend to move together during an earthquake. The area shows stored potential of a M6.1–6.3 earthquake using the assumption that the shallow structures released accumulated strain that has not been released on deeper locked structures.

A global model that forecasts the rates of shallow, large-magnitude earthquakes is formulated by combining seismic and geodetic data. Over time, such models can be used by financial experts to develop a catastrophe bond market, providing opportunities for investors, the insurance industry and communities facing significant seismic risks.

Vertical motions measured by GPS ground stations can be used to track water loads related to precipitation in Ethiopia and Eritrea. The network monitors the seasonal East African monsoon and a smaller regional rainy season. The GPS network is an effective water monitor for the region, where most of the population is agriculture-based.

Combining geodetic and seismic measurements for the moderate 2014 Mw 6.1 Napa, California earthquake shows that rapid earthquake assessment is effective, so in a future real-time implementation, early responders will have more information to know where to concentrate their efforts to mitigate losses.

A plate tectonic model for the Caribbean is derived using from GPS measurements in the region. Analysis shows the subduction edge of the Caribbean plate transitions from fully locked near Hispaniola to partially locked under Puerto Rico and the Lesser Antilles. This behavior implies about one magnitude 8 earthquake every 2000 years.

Analysis of GPS observations before, during and after the 5 January 2013 Mw 7.5 Craig earthquake show that slip during the earthquake averaged about 6 meters. After the earthquake there was substantial deformation over 1.6 years. The earthquake fills a gap and helps to account for plate motion between the North American and the Pacific plates.

A new method of aligning GPS time series on episodes of small earthquakes has revealed new slow slip events (SSEs) that generate a surface displacement that is below the noise level of typical GPS observations. These results add useful details about the spectrum of fault slip from the subtle to the sublime that can help to understand the probability of future earthquake activity along subduction zones.

Intrusive unrest at Bárðarbunga Volcano in Iceland in 2014 shows segmented lateral dike growth creating new crust where the tectonic plates separate.

The Hayward and Calaveras Faults in the San Francisco East Bay are notable strike-slip systems. New interferometric synthetic aperture RADAR (InSAR) observations and seismicity show the faults are connected. The connection of the faults raises the potential risk of a larger earthquake in a populated region.

Eight years of observations of millimeter-level vertical surface changes from a dense network of Global Positioning System (GPS) receivers in the Pacific Northwest tracks a fluctuating water load due to varying precipitation. The observations track seasonal variations (i.e., more rain or snow in the fall and winter) and the drought of 2008-2010.

The North Anatolian Fault (NAF) is major fault system with a history of large earthquakes that extends across Turkey into the Aegean Sea. Twenty years of GPS observations indicate that the Princes’ Islands fault segment under the Sea of Marmara is the most likely segment to generate a magnitude ~7 earthquake in the future with consequences for Istanbul.

Analysis of GPS observations from 1996 to 2011 show that the northern Tohoku region of Japan was accelerating landward and the south-central Tohoku region was accelerating seaward. The measurements and modeling highlight the value of long term observations of seismic regions and the significance of movement between large earthquakes.

The 2010 magnitude 7.0 Haiti earthquake occurred on a secondary blind thrust fault, the Léogâne fault, rather than on the Enriquillo-Plantain Garden fault (EPGF). The best-fitting model simulation shows that the rupture did not trigger the EPGF or the Trois Baies fault, but there has been significant stress buildup on these faults, so future risks should be considered.

Earthquake hazards along the San Andreas Fault System (SAFS) can be assessed from fault slip rate estimates. A layered earthquake cycle model describes the state of the crust in California and helps to reconcile seemingly disparate geologic and geodetic slip rates. Ultimately a better understanding of earthquakes through such observations and modeling can help reduce risks.

A model of plate motions and strain rates for 50 major tectonic plates that makeup the Earth’s surface has been refined from about 22,500 horizontal geodetic velocities. The new Global Strain Rate Model (GSRM v2.1) details not only plate motions and tectonics, but also can be used as a proxy to the risk of earthquakes within plate boundaries.

The North Antarctic Peninsula (NAP) has lost significant ice over decades and the amount and rate of land rebound as the ice is removed can be used to decipher the structure of the crust and upper mantle. Using vertical motion of the land recorded at the Palmer GPS site since 1995, augmented with other GPS data and a simple four-layer model yields a thicker crust and a more fluid upper mantle than expected.

Most of the ocean floor is unknown. Gravity models generated from satellite radar altimetry provide one of the only ways to map the height of the seafloor beneath all of the oceans. Years of data and thousands of satellite tracks have yielded unprecedented detail of major spreading ridges and thousands of seamounts.

The driving forces of the East African Rift System are deciphered by modeling GPS and seismic data of present-day rifting. The models show that density variations within the lithosphere, causing gravitational potential energy (GPE) gradients are driving the current plate spreading in East Africa.

The Plate Boundary Observatory in the western United States is being used as a hydrological monitor. From 2013-2014, the western U.S. lost about 240 gigatons of water, equal to the amount of annual ice loss in Greenland.

A large number of tracks of mostly hadrosaurid dinosaur footprints discovered in Denali National Park shows that hadrosaurid herds lived in multigenerational groups, that juveniles had relatively rapid growth rates, and that a warm polar world could support a significant population of large plant-eating dinosaurs.

Analysis of GPS stations, many that are part of the Plate Boundary Observatory, reveals uplift of the California Coast Ranges and Sierra Nevada Mountains. Much of this uplift comes from groundwater depletion for irrigation. These changes may increase the rate of seismicity on the San Andreas Fault.

About 900 GPS stations, most of which are part of the Plate Boundary Observatory in the western United States, recorded the Earth’s surface response to snow and rain loading. The analysis indicates the seasonal water storage in the mountains in California and shows another way to use GPS for water resource management.

The ice stream in northeast Greenland shows rapid ice loss because of rising air surface temperatures and the loss of sea ice, which is associated with rising sea surface temperatures. The thinning glaciers are detected by a combination of satellite and aerial imagery plus GPS measurements.

High-resolution LIDAR imaging pinpointed locations for paleoseismic studies at Hazel Dell on the San Andreas Fault. Offset and disturbed sediments provide conclusive evidence of larger magnitudes and amounts of displacement for the historical 1838 and 1890 earthquakes, illuminating the nature of the San Andreas fault system.

On 5 September 2012, a magnitude 7.6 earthquake occurred beneath the Nicoya Peninsula, Costa Rica, where geophysicists had anticipated a possible event and established a strategic observational network before 2012. The observations delineate the earthquake rupture area and refine seismic risk.

Azerbaijan encompasses the eastern Kura basin and the Caucasus Mountains rise on its northern border. Recent geodetic observations suggest a significant strain rate across the Kura basin that may signify a greater seismic risk for Azerbaijan’s largest city, Baku.

Imaging and other measurements over two years shows that an ice cliff in coastal Antarctica is eroding much faster than in the past 10,000 years due to recent climate changes. The Antarctic landscape is being transformed much faster than natural processes, even though the continent has a relatively small human footprint.

The magnitude 8.8 Maule Chile earthquake that occurred in 2010 caused subsidence of five volcanic regions in the Andes within weeks of the event. The subsidence was observed via satellite imagery and is attributed to the migration of hydrothermal fluids.

Deep convection in the atmosphere, leading to cloud development and precipitation has been directly observed in the tropics of Brazil using a GPS meteorological site. These observations will help with modeling of weather in the tropics.

GPS data were used to detect volcanic plumes from eruptions of Mount Redoubt in Alaska. Unlike past research, this study relied on the signal strength, or signal to noise ratio (SNR), data. The new analysis can allow for rapid assessment of volcanic ash plumes and help reduce the risks from volcanic eruptions to people, infrastructure and aviation.

The many tectonic plates that make up the surface of the Earth giving us mountains, earthquakes, volcanoes, coastal plains, seamounts, mid-ocean ridges and other features are tied to flow in the deeper mantle. Global GPS measurements show how the plates move relative to one another and these models can be compared to global dynamic models of mantle flow.

The damaging March 11, 2011 Tohoku earthquake caused significant tsunami waves that were recorded on videos by eyewitnesses. Two survivor videos from building rooftops at Kesennuma Bay were combined after the catastrophe and compared with on site terrestrial laser scans, using ground-based LiDAR.

Not only is Iceland spewing out tons of magma from thermal structures, but it also has lots of earthquakes associated with magma and plate movement.

The Yellowstone Plateau Volcanic Field is a very active hotspot and national park with spectacular evidence of volcanic activity on the surface in the form of geysers, hot springs, hydrothermal pools, steaming vents, and seismic activity.

Before becoming a professor of physics at the University of Nevada Reno (UNR), Dr. Friedwardt Winterberg published a paper in 1955 that proposed a direct test to investigate one of the most important theories of modern physics: general relativity.

CMEs are giant bursts of highly energetic plasma that are driven off the surface of the Sun. When a solar storm collides with the Earth it compresses the dayside (facing the Sun) and elongates the nightside of the Earth’s magnetosphere. The hot, energetic ions in the solar storm are driven along and down Earth’s magnetic field lines toward both poles creating magnificent auroras.

The Mississippi Delta along the Gulf Coast of the United States is a major site of sediment deposition from the Mississippi River and conversely a major site of wetland loss from rising seas and subsidence. There is debate about how much and when the delta has risen or fallen due to deposition, subsidence, sea level change, and erosion.

The large earthquakes and tsunamis in Sumatra, Chile, and Japan have accelerated efforts to rapidly determine the location, size, energy, and amount of displacement caused by large earthquakes to assist in response and provide timely warnings of related hazards such as tsunamis.

Isla del Coco, off the coast of Costa Rica, is the only landmass on the Cocos Plate that sits above sea level and thus is the only place where motion of the plate can be measured above the water.

Wayan Suparta has used GPS measurements of atmospheric water vapor to predict when lightning is most likely to strike in Malaysia, a region that experiences large lightning storms throughout the Northeast monsoon season (November-March).

Snow and ice melts in Greenland every summer, but the summer of 2010 melting season was so much longer and hotter than in previous years that an extra 100 billion tons of ice melted from the ice sheet and flowed out to sea. GPS measurements captured the extra or anomalous uplift of the bedrock in response to the greater than normal summer loss in ice mass.

Water vapor is the most abundant greenhouse gas on the planet, yet it is the least accurately measured globally. In order to make useful climate models, robust measurements of the amount of water vapor in the atmosphere are needed.

Researchers have been monitoring melting ice for years in an attempt to understand how ice sheets will affect our changing climate. One way to watch the melting is by using networks of scientific GPS stations such as POLENET. POLENET covers much of the coast of Greenland and Antarctica, as well as a few tall mountains that rise above the ice sheet in the interior of Antarctica. John Wahr of the University of Colorado Boulder works on refining the method of using GPS data to determine melting rates.

Measurements of snow depth are important to climate modelers, meteorologists, and water resource managers, but in the past there has not been both an accurate and widespread method of obtaining these data.

An unexpected landslide could create a disaster for the town of Cerce del Cielo in Puerto Rico, especially if it cuts off access to the only road out of town.

The forces of the Japanese Tohoku-oki 2011 magnitude 9.0 earthquake, the fifth most powerful in the past century, set off a large tsunami that further devastated the shaken island. The earthquake and tsunami also badly damaged a six-reactor nuclear power plant in Fukushima, located 241 kilometers north of Tokyo.

Santorini, a small group of islands located 200 km southeast of mainland Greece, has had a violent past, as evidenced by the collapsed volcanic caldera in its center. The giant Minoan eruption that occurred approximately 3660 years ago may have led to the demise of the Minoan culture, and is responsible for the creation of the large caldera. GPS instruments have been recording the recently renewed activity at Santorini after 60 years of quiescence.

Geodetic imaging such as InSAR combined with GPS has provided the means to view the surface deformation caused by earthquakes at a high level of detail, but currently these images require up to several days to be created by an expert.

As the climate warms, researchers would like to know if hurricanes will increase in intensity and frequency. To explore this theory, more information is needed on the connection between ocean temperatures and the amount of water vapor in the lower atmosphere.

UNAVCO has helped collect and distribute huge amounts of GPS data throughout the world, on the order of several pedabytes, providing unprecedented access to free high-quality scientific data. The next step may be the development of a Geodesy Community Workbench, which would provide a unified framework for analyzing and interpreting GPS data, according to researchers at the University of Nevada in Reno.

Kilauea Volcano has been erupting through the spatter cone Puʻu ʻŌʻō since 1983 on the Big Island of Hawai’i. It has been an exciting, dynamic eruption, ranging from dramatic fissure and lava fountains, to lava streams oozing into the steaming ocean. It has also been destructive, destroying the towns of Kalapana and Kaimū in 1990.

A fountain of lava erupted from a fissure on Kilauea Volcano, Hawaii on March 5, 2011, beginning an eruption that would end four days later. A group of scientists led by Paul Lundgren of the Jet Propulsion Lab have observed the details of this eruption without having to set foot on the volcano using InSAR imagery and UNAVCO GPS station data.

Melting continental glaciers, such as the Stikine icefield in Alaska and Canada contribute to rising sea-level, and therefore it is important to monitor how quickly individual glaciers are losing mass.

Subsidence, or sinking, is a major issue for coastal towns that are dealing with the threat of rising sea-level. A sinking city becomes more susceptible to flooding over time, and knowing the rate of subsidence can help a city prepare for future floods.

UNAVCO’s Plate Boundary Observatory (PBO) includes 75 borehole strainmeters installed predominantly throughout the west coast of North America. Strainmeters work by detecting changes in the size of the borehole, and are sensitive enough to detect a 4 picometer change (smaller than the width of a hydrogen atom). Because they are so sensitive, they pick up every thump and shake in their vicinity, including the arrival of a tsunami wave from across the ocean.