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Solid Earth


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Plate Boundary Observatory Strainmeter Data for Determining Earthquake Characteristics

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.

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2017-05 Solid Earth
Rapid Tremor Reversals Along Cascadia Subduction Zone From Borehole Strainmeter Observations

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.

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2017-02 Solid Earth
Complex Slip Triggered by Complex Geology for 2014 South Napa Earthquake

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.

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2016-12 Solid Earth
2014 South Napa Earthquake Ruptures Surface and Keeps Slipping Long After

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.

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2016-11 Solid Earth
The Rise and Fall of the San Andreas Fault Captured by a Dense Geodetic Network

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.

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2016-10 Solid Earth
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
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
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
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
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
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
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
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 and Solid Earth
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
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
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
Solar Storm Creates Geomagnetic Disturbance Captured by South Pole 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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2013-02 Solid Earth
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 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
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

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Last modified: Monday, 22-May-2017 16:52:32 UTC

 

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