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Snapshots — All Topics


The topics below are snapshot summaries of science discoveries from an ever expanding UNAVCO research community. The summaries include references, related links, related data links, key words and a map center.

Topics

Title Date Category
Pinpointing Slip and Earthquake Location with the Guatemalan Geodetic Network

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.

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2016-06 Solid Earth
Tracking the Rise of the Antarctic Peninsula with GPS

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.

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2016-06 Cryosphere
Geodetic Network Captures Gorkha Earthquake Dynamics

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.

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2016-06 Solid Earth
Alaska’s Subduction Zone and Potential for Large Tsunamis

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.

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2016-06 Solid Earth
GPS and Small Earthquakes Track Periodic Slow Slip That Precedes Large Earthquakes

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.

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2016-04 Solid Earth
GPS Sensors Capture Glacial Earthquakes

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.

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2016-03 Cryosphere
Geodetic Data Yields Rapid Earthquake Assessment

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.

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2016-02 Solid Earth
Peering Into a Volcano’s Interior With Lidar

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.

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2016-01 Solid Earth
Satellite Imagery Reveals Thin Crust Beneath Zagros Mountains

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.

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2015-12 Solid Earth
Earthquake Potential Around Los Angeles, Revealed By Geodetic Data

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.

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2015-12 Solid Earth
Forecasting Global Earthquakes with Seismic and Geodetic Data

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.

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2015-11 Solid Earth
Tracking Precipitation in Northeast Africa with GPS

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.

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2015-11 Human Dimensions and Environmental & Hydrogeodesy
Seismogeodesy for Rapid Earthquake Response

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.

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2015-10 Technology
GPS Defines Caribbean Plate in Motion

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.

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2015-09 Solid Earth
Alaska Earthquake Fills a Seismic Gap and Slips A Bit More After the Main Event

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.

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2015-09 Solid Earth
Finding Small Slow Slip To Understand Fault Zone Dynamics

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.

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2015-09 Solid Earth
Dike Growth and New Crust at Bárðarbunga Volcano, Iceland

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

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2015-06 Solid Earth
When Two Faults Collide, Larger Earthquake Possible in San Francisco Area

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.

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2015-06 Solid Earth
The Highs and Lows of Water Loading in the Pacific Northwest from GPS

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.

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2015-05 Human Dimensions and Environmental & Hydrogeodesy
Identifying Earthquake Hazards Near Istanbul

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.

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2015-04 Solid Earth
Japan Slipping Slowly Over Decades

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.

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2015-04 Solid Earth
Dynamic Rupture Model for the 2010 Haiti Earthquake

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.

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2015-03 Solid Earth
Slip Rates on the San Andreas Fault System

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.

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2015-03 Solid Earth
All the Movable Pieces: Global Model of Plate Tectonics

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.

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2015-02 Solid Earth
Uplift Rate from Ice Loss on North Antarctic Peninsula Suggests More Fluid Upper Mantle

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.

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2015-02 Cryosphere
Mapping the Seafloor with Gravity Models

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.

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2015-02 Ocean
Rifting in Eastern Africa: Geodetic Data Deciphers Spreading Forces

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.

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2014-10 Solid Earth
Plate Boundary Observatory as a Hydrological Network to Monitor Drought

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.

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2014-09 Human Dimensions
Herd of Hadrosaurs in Denali: Insights on Large Herbivores in Warm Polar Region More Than 65 Million Years Ago

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.

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2014-08 Solid Earth
Seasonal GPS Vertical Motions Related to Groundwater Extraction May Enhance Seismicity on San Andreas Fault System

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.

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2014-05 Human Dimensions
Plate Boundary Observatory Evaluates California’s Water Resources

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.

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2014-04 Human Dimensions
Unrecognized Rapid Ice Loss in Northeast Greenland Due to Warming

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.

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2014-04 Cryosphere
Paleoseismic Evidence for Historic Earthquakes Before the 1906 San Francisco Event

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.

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2014-04 Solid Earth
Anticipating and Monitoring a Large Earthquake in Costa Rica

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.

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2014-01 Solid Earth
Seismic Hazards in Azerbaijan Informed by Geodesy

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.

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2013-11 Human Dimensions
Antarctic Ice Cliff Eroding Fast Due to Climate Change

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.

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2013-10 Cryosphere
Big Chilean Earthquake Causes Andean Volcanoes to Subside

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.

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2013-08 Solid Earth
Following Rising Moisture, Clouds, and Rain in the Tropics with GPS

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.

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2013-07 Atmosphere
Detecting Volcanic Plumes with GPS Data

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.

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2013-07 Atmosphere
How the Mantle Moves You: Connecting Plate Motions to Mantle Dynamics with Global GPS

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.

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2013-06 Solid Earth
Dangerous Outflow After Massive Inflow: Estimating the 2011 Japan Tsunami Current Velocity With Terrestrial Laser Scanning

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.

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2013-06 Human Dimensions
Modeling Iceland Volcano’s Magma Body with Geodetic Data: More Eruptions Fed by Thin Vertical Tube

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.

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2013-06 Solid Earth
Standing Waves in Yellowstone Lake Sense Magma Body at Active Hotspot

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.

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2013-03 Solid Earth
Quality Assessment: A new technique to assess and monitor long-term quality of GPS data

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.

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2013-03 Technology
Solar Storm Creates Geomagnetic Disturbance Captured by South Pole GPS

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.

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2013-02 Atmosphere
Sea Level Rise on the U.S. Gulf Coast

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.

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2013-02 Environmental & Hydrogeodesy
Rapid Earthquake Assessment with Geodetic Networks

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.

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2012-12 Solid Earth
Island on the Move, Following Plate Motions with Continuous GPS

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.

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2012-12 Solid Earth
GPS helps predict lightning strikes in Malaysia

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).

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2012-11 Atmosphere
Observing Abrupt Melting in the Greenland Ice Sheet and Relating Air Mass Changes to Bedrock Changes

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.

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2012-11 Cryosphere
Researchers using GPS stations throughout the world to measure water vapor in the atmosphere, a greenhouse gas that contributes to global climate change

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.

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2012-09 Atmosphere
Solving the mysteries of the melting ice sheets: using the details to determine the cause

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.

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2012-09 Cryosphere
Bounces in GPS signals reveal snow depth

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.

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2012-09 Environmental & Hydrogeodesy
Real-time GPS can send the alert before a deadly landslide

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.

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2012-09 Human Dimensions
Estimating plate boundary slip during large earthquakes: seafloor geodesy during 2011 Tohoku-oki Earthquake in Japan

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.

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2012-09 Ocean
GPS records the accelerated swelling of Santorini, a Greek volcano that last erupted in 1950

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.

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2012-09 Solid Earth
Researchers working towards automated generation of life-saving imagery following an earthquake using UNAVCO datasets

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.

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2012-09 Technology
COCONet, a GPS network in the Caribbean, will aid in hurricane forecasts

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.

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2012-09 Atmosphere
UNAVCO facilitates access to inter-disciplinary datasets, and supports the development of a Geodesy Community Workbench

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.

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2012-09 Technology
Students monitor an active Hawaiian volcano in real-time

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.

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2012-09 Human Dimensions
Satellite imagery allows scientists to safely see the fine details of an eruption in Hawaii

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.

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2012-09 Solid Earth
Tracking the melting glaciers of Alaska, pixel by pixel with satellite imagery

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.

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2012-09 Cryosphere
GPS can help monitor a sinking city

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.

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2012-09 Environmental & Hydrogeodesy
UNAVCO's Strainmeters Record the Arrival of Tsunamis on the west coast of North America

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.

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2012-09 Ocean

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Last modified: Thursday, 23-Jun-2016 17:21:08 UTC

 

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