MAGNET GPS Station - Photo by Geoff Blewitt

Link to our Data Products Page:



Quick Links to Data Products:


The plates frames are defined using Euler rotation poles found in the supplement of Kreemer et al., 2014. The table is also separately available at this link. The format of the file is latitude(deg), longitude(deg), magnitude (deg/Myr), plate ID. To be entirely consisent with the assumed kinematic model, plate velocity at any latitude and longitude can then be computed using the formulas (B1) and (B2) in Kreemer et al., 2014, where Earth’s radius R = 6371 km.

Each station is associated with one or more tectonic plates, as defined by Bird, 2002. Every station is on at least one plate, but some stations can have more than one plate associated with them if the second plate is close. For every station there is at least one large plate in the set assigned to it (the large plates being PA, NA, SA, EU, AF, AN, AU). A text file that lists the plates associated with each station is available HERE.

Latest News

[August 3, 2022] New Western US Strain Rate Map

Kreemer and Young present a new suite of strain rate models for the western United States based on geologic and geodetic data.

Published in Seismological Research Letters, they present the very interesting finding that slow and fast deforming areas of the continent exhibit a different relationship between seismicity and strain rates. Seismicity rates increase relatively slowly with strain rate in faster deforming areas.

Western US strain


[July 26, 2022] System Outage Planned for Thursday Morning July 28, 2022

Please note that our web pages will be down this coming Thursday morning for a planned system upgrade. NGL data products will be not available until we complete the upgrade. Thanks for your patience.


[June 15, 2022] New Paper: Uplift of the High Plains Aquifer

Just published this week in the AGU Journal Water Resources Research: Overacker et al., (2022) use GPS data to show that the High Plains Aquifer in the central United States is undergoing active uplift that is accellerated by drought.

The High Plains Aquifer, also known as the Ogalalla aquifer, is the largest grounwater system in the United States. We image an uplift anomaly of ~1 mm/yr that is focused near the southern portion of the system and is associated with water withdrawal. The aquifer is unconfined, so water loss results in load reduction uplift, not compaction-driven subisence as is commonly observed in other systems such as the California Central Valley. The difference in physical mechanism responsible for vertical land motion revereses the sign of active uplift associated with groundwater loss, and highlights the utility of integrating climate, geodesy, hydrology and geology when studying large groundwater systems.

Ogallala Uplift


[June 1, 2022] We Are Back Online.


WE'RE BACK! University power issues triggered failure of our web server on May 21. Our web pages and online data products are now restored and back online.

Please note that time series text files and MIDAS velocity solutions will be up to date as usual, but time series plots on the station pages will be static until we repair the failed server. Sorry for the inconvenience. Thanks for your patience, Folks!



[May 19, 2022] Important System Note: File Format Change for .tenv3 and .vel


Please note that because of user demand and better internal consistency we have enhanced the format of the time series text files (with suffix .tenv3) and midas velocity text files (suffix .vel) to include three additional columns added to the right side of the file. These columns contain the latitude, longitude (in degrees) and height (in meters) of the station. In the case of the .tenv3 files these values change in a way consistent with the changes in daily position, in all three coordinates.

Apologies if this change disrupts workflows that use these files. However, the presence of the additional information should add simplicity in many applications that use them.





[October 25, 2021] Out Today: Spotlight on Global Vertical Land Motion

See the Research Spotlight in Eos on our new paper (Hammond et al., 2021) that describes using GPS to measure vertical land motion around the world.

The analysis uses data from over 19,000 locations to estimate the rates, patterns, budgets and sources of the vertical movement of the land surface that is driven by various processes in the Earth such as plate tectonics, glacial isostatic adjustment, the earthquake cycle, changes in aquifers and hydrological loads.

The methodology is used to generate new continually updated vertical land motion data product based on our GPS data holdings and processing system which can be used to improve understanding of the driving factors behind sea level rise in coastal areas.

The article was also featured on the cover JGR for volume 127, issue #7, and was selected by the editors to appear in a special collection of papers identified as pivotal research on the climate crisis published in AGU journals.


Sea level near Balboa Pier

[July 30, 2021] M 8.2 earthquake in Alaska!

About 35 hours ago (July 29 UTC) a very large earthquake struck the Aleutian Penninsula along the convergent plate boundary between the Pacific and North America plate. At M 8.2 it is the largest in Alaska in over 50 years. This thrust earthquake occurred near the location of a similar, but smaller (M 7.8) event last year (see entry below for July 23, 2020).

We accessed data from NSF's Network of the Americas operated by UNAVCO, and other networks in Alaska, and computed position time series, with JPL's Gipsy software and rapid orbits. Using 5 minute positions we estimated a preliminary set of coseismic offsets which are shown in the figure below and provided as a text file.

The largest GPS-measured displacement was ~43 cm, occuring at station AB13, which also subsided vertically by ~7 cm. A coherent displacement pattern extends far to the northeast, past Anchorage (~800 km from epicenter) and possibly as far north as Denali National Park (>900 km). For scale... this would be like an earthquake in California moving the state of Utah by several mm!

Text file with preliminary coseismic displacements.

Map of coseismic displacements

[July 22, 2021] Update on Antelope Valley Earthquake response: Complicated by wildfire!

Below is the latest map of offsets that include new data collected after the earthquake. These are based on more data, 24 hour rapid solutions, and are more precise that those from 5 minute time series shown previously. The large southward displacement of LANT remains, however its aziumth now seems more south-southwest. Stations for which we will eventually have offsets are labelled in blue, many of these now have receviers at them recording data. However, access to stations west of the epicenter is almost totally shut down because of the Tamarack fire which is at this time only 4% contained.

Click here for preliminary text file of the offsets. The uncertainties for offsets at stations BFLT, TOPA, RISU and SEE are larger than the others because they had not been surved as recently prior to the earthquake. These uncertainties will be reduced with further surveying.

GPS Offsets Antelope Valley 20220722
GPS Offsets Antelope Valley 20220722

[July 16, 2021] Highlights from the Field: the M6.0 Antelope Valley Earthquake

Here is a quick update on the MAGNET GPS deployment for the Antelope Valley earthquake. We were in the field for several days and retrieved data from stations WALK, EWLK, GILL, INDI, CALA, ARMY, FLAT, LUCK, ROUG, BODY, CONW, BRID, LANT, SNRA, EBBS. Those data were processed yesterday and we obtained post-event positions for most of them. We also moved receivers into stations NORA, DNNL, PCST, BRVL, SILV, MARK, SCTS, KINS, which will give us displacements on the west side of the event. We will let those stations collect data for at least a week before returning get data from them. If more earthquakes occur in the near future there is a nice network in place to record it.

The figure below is preliminary and has the scale expanded to emphasize the small signals in the medium-field (within ~50km) from the epicenter. Note the scale bar indicates size of 5 mm displacement. The vector for LANT goes off the page at this scale. These offsets are computed from 5 minute time series processed at NGL which are available at our station pages.

The vectors show P136 and SNRA moving toward epicenter, EBBS, P143, P135, ROUG, LUCK, BODI, BRID moving away from epicenter, and other stations further from the epicenter showing noise or zero offsets (e.g. WALK, DECH, etc.). These offsets show ~east-west extension and ~north-south contraction. look more or less as expected from a normal faulting earthquake. However there could also be an dextral component to the slip which will require detailed modeling to explore completely.

Data from the NSF Network of the Americas at stations P143, P136, P134, P654 operated by UNAVCO are also used in the analysis.

There are some pictures from the deployement... see Bill's site with pictures and video.

GPS Offsets Antelope Valley station LANT

[July 11, 2021] - NGL Responds to the M6.0 Earthquake in Antelope Valley

We now have some data from the MAGNET GPS stations that were running during the this event. On the 9th we retrieved data from LANT and ROUG and installed more receivers at other nearby stations. Data retrieved have been processed and we are seeing offsets consistent with the InSAR from gCent posted on twitter.

LANT is located at about the middle of the gCent interferogram. With 5 minute GPS solutions we got enough data between July 8 22:49:48 and midnight UTC to get a ~10 cm subsidence at LANT, with just a little over an hour's data, roughly consistent with the interferogram, and with normal slip on the plane directly beneath the station.

LANT also moved ~4 cm horizontally to the SSE (see plot below), consistent with it being located on the hanging wall of an east dipping fault (Slinkard Valley Fault or Antelope Valley fault) that slipped in a right-normal oblique motion. This could help resolve some uncertainty in the mechanism if it holds up as we collect more data.

We will be continuing to move receivers into stations near the event, and collecting more data from stations that were running over the next several days. GPS Offsets Antelope Valley station LANT Note the post-earthquake data is right of the green dashed line which denotes the time of the event.

[July 3, 2021] - New Paper and Data Product: Global Vertical Land Motion

Sea level rise is a global problem. Vertical motion of the land directly affects coastal relative sea level rise, and has many possible driving mechanisms, e.g., plate tectonic movements, earthquakes, subsidence from aquifer withdrawal, post-glacial rebound, mantle flow, or other active geophysical processes.

The precision, coverage, and prevalence of open data holdings that are now available from GPS stations around the world provide a unique dataset for constraining these movements on a global scale. Since GPS stations around the world are of various quality and very heterogeneously distributed, our analysis emphasizes robust methods to obtain geographically balanced estimates of a global field. We use these estimates to show the rates and patterns of vertical land movement and evaluate the balance of uplift and subsidence across the Earth's surface.

The method and results are described in a new manuscript published with open access in the Journal of Geophysical Researh: Solid Earth.

Click here to access the data product that provides maps and rates at over 2300 tide gauges around the world.

Development of this product was made possible trough funding from the NASA Sea Level Change Team.

Figures From VLM paper
Color scale in mm/yr.

[May 18, 2021] - New Quality Assurance (QA) Plots Now Available on Station Pages

Those interested in our GPS solutions may find utility in a new data product that is now available for all stations in our holdings. For some time the Quality Assurance (QA) files have been produced and made available as text files, linked from the station pages (e.g. for station P141 you can download the the P141 QA file).

Now these files are available in graphical form as plots that can be easily compared to the position time series. The plots show time series of parameter values that provide in-depth knowledge of the results and quality of the data processing, including, for example, the number of phase biases and percent of phases accepted, metrics that show how well the derived positions fit the code and phase data, plus many others. Importantly, the files can reveal when equipment performance is degrading, or external factors effect the results of processing. Thus the QA parameters can be used to track down errors, problems, and/or equipment issues with the GPS station.

The tab for the QA plot is the last tab listed for the time series plots on each station page.

The guide to the QA files describes the parameters and how they can reveal factors that influence processing results.
Location of QA Tab on station page for P141.

[January 21, 2021] - MAGNET featured in Bloomberg Video


NBMG Director Jim Faulds appears in a fun Bloomberg story about Highway 395, Tesla and the Walker Lane. Starting around 3:00 he discusses the MAGNET Network's role in measuring the faults and deformation in the Walker Lane.
Check it out:

[January 9, 2021] - New Paper on Common-mode Filtering

There is a new paper from Corné Kreemer and Geoff Blewitt from NGL on reducing scatter in geodetic time-series. ⁦ The paper presents a method that removes more noise than any other previous common-mode “filtering” technique. The secret is to define “common” as local as possible, and use all stations.

The paper is available at the Journal of Geodesy.

The example below-right is a MIDAS velocity time-series for station KIN1 using 2.5-year periods centered on a moving window for every 0.2 years. Red/blue lines and outline are velocity and one standard deviation for unfiltered and filtered time-series, respectively. Velocities are plotted relative to long-term trend and, for reference, the dashed and dotted lines are 1 and 2 standard deviations in that trend, respectively. Please see the manuscript for details.

Figures From Kreemer+Blewitt paper

[December 23, 2020] - A Pair of New Earthquake Geodesy Papers

The challenges in 2020 were many. Included in these were significant earthquakes in Nevada and Idaho, both with magnitude ~6.5. Permanent displacements of the Earth surface from these events were detected in GPS networks and have been used to learn more about the earthquake cycle in the seismically active part of the western United States.

The Monte Cristo Range earthquake of May 15, 2020 struck the central Walker Lane, squarely within the MAGNET semi-continuous GPS network where ~1 dozen of our receivers were serendipidously deployed near the epicenter, providing an excellent opportunity to observe co- and post-seismic left lateral strike slip deformation. The event triggered a rapid and sustained field deployment that involved students and staff of the Nevada Burean of Mines and Geology who summarized rapidly obtained geologic and geodetic data for the event. In the published study Hammond et al., 2020 present the results obtained from the deployment. They were able to constrain the coseismic and postseismic displacement fields, and use them to compare and contrast geodetic, seismic and geologic assessments of seismic moment. They also found that postseismic deformation continued for at least months afterward.

GPS-measured strain accumulation prior to the event may have been optimized by the postseismic movements from previous 20th century earthquakes in the Central Nevada Seismic Belt, suggesting that faults in the Great Basin may interact and influence the timing of one anothers coseismic release.

Pollitz et al., 2020 investigated the M 6.5 Stanley, Idaho earthquake with a combination of InSAR, GPS and seismic waveform data. They found that the event had up to 2 meters of left‐lateral and normal slip on an ~10 km long south‐southeast‐striking fault, which could represent a previously unidentified northern extension of the Sawthooth fault. The complex event involved minor slip on conjugate planes associated with the Trans-Challis fault system, and complementary postseismic afterslip.

Both studies used data from the NSF Network of the Americas, operated by UNAVCO. They have both been published in a special issue of Seismological Research Letters on the recent Intermountain West Earthquakes.

Photo of something


[October 9, 2020] Western Transverse Ranges Research Spotlight in Eos

In collaboration with a multi-institution team NGL has published a new study on the long- and short-term uplift of the western Transverse Ranges, and how these motions relate to fault activity, slip rates and earthquake potential. The study integrates geodetic data with fault and other geologic data to model subsidence along the Santa Barbara coastline and uplift of the Santa Ynez Range. The uplift and subsidence are consequences of recoverable elastic deformation associated with interseismic locking on faults dipping under the Western Transverse Ranges. Long term uplift of the Santa Barbara coast is achieved through the intermittant earthquakes that reverse the short term subsidence.

Eos is now featuring a research spotlight on the work. To go directly to the article click on the image below, or see the post on Twitter. The Johnson et al., 2020 article is now published in the Journal of Geophysical Research - Solid Earth.

Photo of Santa Barbara Coast from Offshore


[July 23, 2020] M 7.8 Alaska Penninsula

On July 22, 2020 a thrust earthquake occurred offshore at 28 km depth within the Aleutian trench where the Pacific Plate subducts beneath the North American plate. The event caused coseismic movement of a number of stations on the Alaska Peninsula and Aleutian Islands. We estimated coseismic offsets the day after the earthquake from 5 minute sample rate time series that were derived using rapid orbits from the Jet Propulsion Laboratory. Most of the stations are from the UNAVCO operated Network of the Americas. Near the end of the peninsula the horizontal offsets indicate south-southwest motion, consistent with trenchward motion of the hanging wall. Significant vertical motions were also observed, for example station AC12 moved upward over 34 cm and station AC28 moved downward 7.5 cm.

Map of GPS displacements

Preliminary coseismic offsets table based on next-day 5 minute solutions is : here.


[June 28, 2020] M 5.8 Earthquake Near Lone Pine, Eastern California shakes the Southern Sierra!

A moderately sized earthquake struck the southern Owens Valley on June 24, 2020, causing widespread shaking and rock fall in the southern Sierra Nevada. The event was detectable in small movements of several nearby continuous GPS stations including P093 and P465 from NSF's Network of the Americas operated by UNAVCO. P093 moved south by about 6 mm and P465 moved west about 4 mm. The direction of movements are characteristic of coseismic contraction and extension that are consistent with the P and T axes the seismic moment tensor. Precision of these measurements will improve as more post-event data are collected. Additionally, more vectors will become available once data are retrieved from stations in UNR's MAGNET GPS network (locations shown with blue triangles in figure below).
Map of Earthquakes and GPS displacements

Preliminary coseismic offsets table: here.


[June 26, 2020] M 7.4 Earthquake Oaxaca, Mexico

A large earthquake struck southern Mexico on June 23, 2020. Preliminary cosismic displacements are available which show large offsets for stations nearest the epicenter. The station OXUM moved over 16 cm southwest and rose vertically over 4 cm.
Map of Earthquakes and GPS displacements

Preliminary coseismic offsets table: here.


[June 19, 2020] Update on Monte Cristo M6.5 Earthquake


Map of Earthquakes and GPS displacements

Update on coseismic offsets table: here.


[June 2, 2020] Update on Monte Cristo Earthquake

Over the past week data collection on the Monte Cristo Range earthquake has continued. We now have coseismic offsets on 24 MAGNET stations, 15 of which are recording signficant coseismic displacement. Stations in each of the four quadrants of the displacement field have returned data, revealing the systematic horizontal NW-SE extension, NE-SW contraction, characteristic of a strike slip earthquake. An updated offset map and table are provided below. The largest offset so far is at station COLU, on the west side of the Columbia Salt Marsh, which has 145 mm displacement to the northeast. These offsets and some preliminary modeling are now sufficient to favor slip on a left lateral plane striking 78 degrees clockwise from north, similar to what are indicated by InSAR, aftershock, and surface rupture data.

Map of Earthquakes and GPS displacements

A table of preliminary coseismic offsets is available for download here.


[May 24, 2020] Update on Monte Cristo M6.5 Earthquake

Since the earthquake occurred on May 15, we have gotten some of the first data back from MAGNET stations to our laboratory and processsed. These data are beginning to provide constraint on the near- to medium-field coseismic displacement pattern. Among these were one of the closest stations to the epicenter MONT (17 km from epicenter), that moved 66 mm to the southwest in the event. We also have data back from MAGNET stations CHIA, ROJO, PACT, and RHIL. Data from these stations were used to compute offsets which are plotted below. Data collection in MAGNET continues and will be used to fill in the displacement pattern.
Map of Earthquakes and GPS displacements

More information on the event can be found at UNAVCO's event response page.


[May 20, 2020] Preliminary Coseismic Displacements from 2020 Monte Cristo Range Earthquake

Data from regional continuous GPS stations of the NSF Network of the Americas (formerly the EarthScope Plate Boundary Observatory), and the USGS California Volcano Observatory are processed at NGL using rapid orbits and products from the Jet Propulsion Laboratory. From these rapidly generated position time series we can make preliminary estimates of the permament coseismic change in Earth shape from the Monte Cristo Range earthquake.

Our first look at the pattern of horizontal displacement is shown in the figure below. It indicates horizontal shifts consisent with the seismic moment tensor and aftershock seismicity that suggest a left lateral slip on an east-northeast striking plane. The GPS station TONO at Tonopah, Nevada moved about 5 mm southeast, station P627 near the California/Nevada border moved about 6 mm north. Stations north of the epicenter (P132, P133) moved in the opposite sense, characteristic of coseismic displacement. These data show significant ground movements over 100 km from the epicenter.

NGL is currently gathering data in the part of the MAGNET GPS network (red triangles) nearest the epicenter. As new data roll in over the next days to weeks we will fill in the (likely larger) near-field displacements to complement those from the continuous stations (blue triangles). For one MAGNET station we have already brought data into our lab, processed and released solutions (site CHIA), more will follow.

Map of preliminary rapid coseismic displacements


[May 15, 2020] M6.5 Earthquake in the Monte Cristo Range!

The Nevada Geodetic Laboratory is currently deploying GPS at ~30 stations around the epicenter and aftershock sequence of the May 15, 2020 Monte Cristo Range M6.5 earthquake. The map below shows the locations of MAGNET GPS stations, continuous GPS stations from other networks, and seismicity since January 1, 2020, mainshock is shown with a star. The nearest continuous station (P627) is about 50 km distant, whereas MAGNET has about a dozen stations within this radius. The legend indicates which MAGNET stations were already in place at the time of the event, and which stations NGL plans to occupy in the near future. These stations will be visited multiple times in the coming months to download continuous observations that constrain coseismic offset, potential postseismic displacement, and establish monitoring in the event of further earthquakes.

The aftershocks of the M6.5 indicate it was likely a left-lateral event whose slip plane can be extrapolated WSW to intersect the swarm east of Mono Lake that has been ongoing for several weeks. The aftershocks also lie along the southern extrapolation of the Benton Springs, Petrified Springs and Gumdrop Hills right lateral strike-slip faults that accommodate northwest-southeast directed Walker Lane shear deformation. The Mina Deflection is a zone with left-lateral faulting similar to the strike described by the cloud of aftershocks.
Map of area of Earthquake and GPS network
More information is available on the NBMG response page and on the USGS event page. The Nevada Seisloogical Laboratory is continuously posting earthquake updates and is gathering near field seismic recordings.


[February 18, 2020] New article on NBMG's studies of Walker Lane tectonics and earthquakes!

The Nevada Geodetic Laboratory/Nevada Bureau of Mines and Geology is engaged in new and ongoing work on the Walker Lane in the western Great Basin of the United States. Mike Wolterbeek (UNR) summarized these efforts in a new Nevada Today magazine piece on new efforts and technologies that are being used to read the signs of active crustal deformation in the Walker Lane, and the earthquakes it generates.

[February 10, 2020] NGL Contributes to New Report from the National Academy of Science

Satellite remote sensing is a primary tool for measuring global changes in the land, ocean, biosphere, and atmosphere. Over the past three decades, active remote sensing technologies have enabled increasingly precise measurements of Earth processes, allowing new science questions to be asked and answered. As the demand for measurement precision increases, so does the need for a precise geodetic infrastructure.

Geoffrey Blewitt is co-author on a new report from the National Academy of Science: "Evolving the Geodetic Infrastructure to Meet New Scientific Needs" which summarizes progress in maintaining and improving the geodetic infrastructure. The report identifies improvements to meet new science needs that were laid out in another Academy report "Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space". Focusing on sea-level change, the terrestrial water cycle, geological hazards, weather and climate, and ecosystems, this study examines the specific aspects of the geodetic infrastructure that need to be maintained or improved to help answer the science questions being considered.
Cover of the National Academy Report

[January 30, 2020] M7.7 Earthquake Near the Cayman Islands

On January 28, 2020 a large and shallow strike-slip earthquake occurred at the northern boundary of the Cayman Trough on the Caribbean Sea floor. The event epicenter was between the Cayman Islands, Cuba, and Jamaica, with shaking felt as far away as Florida. GPS data show that stations on the Cayman Islands and Jamaica moved in a fashion consistent with left lateral slip on the fault. The maximum displacement observed was at the UNAVCO-operated COCONet station LCSB which moved over 170 mm to the northwest.

We used rapid orbits from JPL and 5 minute sample rate time series to compute preliminary coseismic offsets. These displacements are depicted on the map below with red vectors for 52 stations. Below the map is an example 5 minute sample rate time series for station LCSB that shows with the red line segment the time interval used to select data to estimate the offsets.
Map of Carwibbean Sea region with vectors showing GPS measured displacements.
GPS Time Series Plot of East, North and Up components for station LCSB

[January 15, 2020] Damaging earthquake sequence in Puerto Rico

A sequence of earthquakes struck southwest Puerto Rico between January 6 and January 11, with at least 8 events over M 5.5 and a main shock with M 6.4. This event poses a challenge for earthquake geodesy because of the difficulty in separating multiple events per day while using precise 24 hour solutions. We simplified our coseismic displacement estimation by solving for a single offset per station on the day of the main shock, January 7, from 24 hour sample rate GNSS solutions using rapid orbit products from the Jet Propulsion Laboratory. The largest offsets observed were over 20 mm, at the NSF-supported Network of the America's station P780, operated by UNAVCO and processed by NGL (station page for P780).
Map of Puerto Rico showing GPS-measured displacements.
The map was made using this a table of preliminary coseismic offsets.

[November 28, 2019] All NGL GPS Holdings Reprocessed and Available in IGS14!

Newly updated GPS data products are now available our online system. All data in the NGL holdings have been reprocessed with the new and improved GipsyX v1.0, software released this year. The new results use improved models including the VMF1 mapping function and nominal troposphere, elevation weighted observations, and higher order ionospheric calibrations, improved JPL Repro 3 orbits, and the latest global reference frame IGS14. Also, time series and MIDAS velocities are now available in 25 tectonic plate fixed reference frames which adjust the horizontal trends only. New station pages have been developed that present these solutions in IGS14, plate fixed reference frames and detrended time series.

Thanks for your patience as we work out the few remaining issues with the web pages.

Happy surfing and Happy Thanksgiving!

[July 7, 2019] Update on M7.1 Ridgecrest Earthquake

Below is an image of the coseismic displacement of the Earth surface that occurred during the M7.1 earthquake near Ridgecrest on July 5, Pacific Time. The maximum movement of a GPS station was over 500 mm, or about half a meter at station P595, about 20 km east of the epicenter. Notably, most of southern California moved because of the event to some degree, though in most places this movement was small, under 10 mm. Similar to the previous M6.4 event on July 4, the movements are approximately east-west extensional, and north-south contractional. This is consistent with right lateral slip on a northwest striking fault plane.

Map of Ridgecrest area showing GPS-measured coseismic displacements.
These data are from several geodetic networks, the largest of which is the Network of the Americas (NOTA), a core component of the NSF Geodetic Facility for the Advancement of Geoscience (GAGE).

The plot is made from this table of preliminary offsets.

[July 6, 2019] M7.1 Earthquake near Ridgecrest, CA

On July 5, one day after the July 4 M6.4 earthquake, an M7.1 event near Ridgecrest, CA generated much larger permanent movement of the Earth surface. For a subset of continuous GPS stations, NGL processes data using JPL's ultra-rapid orbit products, allowing us to calculate coseismic offsets for a few stations on the same day as the earthquake. Results of this ultra rapid analysis are shown below.

We can already see from these early results that the movements are much larger and extend a greater distance than those from yesterday's event. For example, the GPS station GOLD (which is over 70 km southeast of the epicenter) moved ~31 mm, much greater than it moved during yesterday's earthquake (see previous post below). Today's result shows that significant movement extends at least 150 km from the epicenter, and may reach south of the San Andreas Fault. The pattern of the displacements gives us confidence that what we are seeing is from the earthquake. The movement was approximately east-west extensional, and north-south contractional, consistent with the active tectonic strain rate field. The movement is also consistent with the earthquake moment tensor, which along with seismic data, indicate a right lateral strike slip event on an approximately northwest striking plane.

We expect to have results for a much larger number of GPS stations soon.

Map of Ridgecrest area showing preliminary GPS-measured coseismic displacements for M7.1 earthquake

[July 5, 2019] Fourth of July M6.4 Earthquake Near Ridgecrest, California

The map below shows preliminary coseismic horizontal vector displacements for the M6.4 earthquake that occurred near Ridgecrest, California yesterday. The 5 minute sample rate time series were obtained using rapid orbits from the Jet Propulsion Laboratory. Maximum displacements are approximately 10 cm, describing east-west extension and north-south contraction, consistent with a strike-slip event. Four character codes indicate GPS station names. Vectors have 95% confidence ellipses on their tips.

Map of Ridgecrest area with GPS-measured coseismic displacements
The plot was made using this table of preliminary coseismic offsets.

[June 3, 2019] Possible small displacements observed in the Peru M8.0 earthquake

On May 26 an M8.0 earthquake occurred beneath northern Peru. The USGS report on the event indicated the focus was very deep (>110 km) and thus less surface displacement is expected compared to a shallow event. We looked at GPS data from stations within 1585 km of the event and found that stations to the east of the epicenter have a systematic eastward movement, all under 4 mm. The individual offsets are near the uncertainties, but taken together the mean eastward motion may be significant. These results have been rapidly determined, and more more definitive results will be available when more data has been collected after the earthquake.
Map of northern South America showing GPS-measured displacements

[May 24, 2019] New Paper! Drought-Triggered Inflation and Earthquakes at Long Valley Caldera

In a new study we have explored how recent drought periods in California influence the timing of Long Valley active caldera inflation near the city of Mammoth, California. The study uses GPS and seismic data to show how uplift of the Sierra Nevada and magmatic inflation at Long Valley accelerated when the drought initiated in late 2011. The subsequent inflation changed the distribution of active tectonic strain rates in the adjacent central Walker Lane, east of the Sierra Nevada, effecting seismicity rates. Earthquakes occurred more frequently in places where the geodetic strain rates increased, suggesting that hydrological surface loading (e.g. from changing levels of aquifers, snow and lakes) affects the magmatic system in ways that subsequently influence earthquake occurrence. The study captures in new detail the complex links between between climate, active volcanos and earthquakes in eastern California and Nevada.

The work is a collaboration between the Nevada Bureau of Mines and Geology and Department of Mathematics and Statistics in the UNR College of Science. The study appears as a new accepted article in the Journal of Geophysical Research - Solid Earth.
Topographic map of Long Valley with GPS time series, PDSI and GRACE
Hammond, W.C., C. Kreemer, I. Zaliapin, G. Blewitt, 2019, Drought-triggered magmatic inflation, crustal strain and seismicity near the Long Valley Caldera, Central Walker Lane, Journal of Geophysical Research - Solid Earth, 124(6), p. 6072–6091, https://doi.org/10.1029/2019JB017354.

[April 18, 2019] WIRED Article on High Tech Walker Lane Geology Mentions NGL

Space geodesy helps researchers with age old geological conundrums and new theories about the future of the plate boundary according to a new WIRED article on the Walker Lane. Interviews with NBMG scientists Jim Faulds, Bill Hammond and Rich Koehler with writer Geoff Manaugh contribute to this fun, thought provoking piece.


[December 1, 2018] Anchorage Earthquake Coseismic Displacement

Yesterday morning, November 30, 2018, an M 7.0 earthquake struck directly beneath Anchorage, AK causing landslides and widespread shaking. The event was over 40 km deep with a normal slip style mechanism causing some to suggest it was result of a tensional earthquake in the subducting oceanic lithosphere of the Pacific Plate. Here we show that coseismic horizontal displacements were about 2 cm in Anchorage. We obtained these offsets from 5 minute sample rate solutions calculated with JPL rapid orbit products. The horizontal vectors (Figure below) show ESE displacement both east of, and west of, the epicenter. The distance from Anchorage over which displacements are significant extends further east than west. They also show north-south contraction, with stations north of the epicenter moving south, and stations south of the epicenter moving north. Together these observations suggest that the slip occurred on the shallower, down to the east, nodal plane obtained from the seismic data and presented by the USGS.
Map of coseismic displacement from the Anchorage M7.0 earthquake
The rapidly derived coseismic displacents were used to make the figure.

[October 19, 2018] New paper on seasonal strain and seismicity in California and Nevada

The changing amount of water and snow mass that lays on top of the Earth's surface is one possible explanation for observed seasonal variations in seismicity. This hydrological loading would change the state of stress inside the crust minutely with the seasons. We image the seasonal stress variation by using the horizontal seasonal displacements of GPS monuments in the southwestern United States. This reveals large‐scale seasonal patterns of the crust contracting and extending in‐phase with the Earth's surface going down and up, respectively, particularly in northern California which experiences a large excess of water and snow in late winter. The seasonal variations in horizontal deformation there correspond to variations in the number of mainshocks, with more earthquakes occurring when the crust is under extension. In southern California, we see no correlation with the number of mainshocks. In both regions, seasonal deformation correlates with the proportion of large earthquakes and shows an anticorrelation with the aftershock production. So even though seasonal deformation may not directly trigger earthquakes, if an earthquake happens during the right season, it seems to be able to grow a little larger, releasing a little more stress than it otherwise would and reducing the need for (more) aftershocks.

Kreemer, C., and I. Zaliapin, 2018, Spatio-temporal correlation between seasonal variations in seismicity and horizontal dilatational strain in California, Geophysical Research Letters, 45. (18), p. 9559-9568, https://doi.org/10.1029/2018GL079536.


Left panel: Dilatational strain (positive is extension, negative is contraction). Superimposed are the orientations and relative size of the principal axes: white vectors are positive (extensional) and black are negative (contractional). Principal axes reflect spatial averages and for each set the largest axis is normalized to unity. Grey lines are major faults (i.e., with Quaternary slip rate ≡2.5 mm yr-1). Right panel: Vertical displacements inferred from the GPS Imaging technique (Hammond et al., 2016). Superimposed are horizontal displacements (spatially down-sampled) derived from MELD (Kreemer et al., 2018). Numerical results are provided in the paper's Supplemental Information.


[September 24, 2018] NGL publishes new paper in Eos!

Harnessing the GPS Data Explosion for Interdisciplinary Science

More GPS stations, faster data delivery, and better data processing provide an abundance of information benefitting many kinds of Earth science. At NGL we make our data products for over 17,000 stations available online, including metadata, lists of stations, plots of position coordinates, tables of data holdings, and descriptions of new items relating to the products. The service and philosophy, known as Plug and Play GPS , has been documented in a new paper published today in Eos.

NGL is committed to continuing to provide this long-running service to the scientific community, and we encourage researchers to explore these data sets and apply their creative skills to scientific investigations that have yet to be conceived.

Henceforth we request that citation of the data processing and products presented on our website should be:

Blewitt, G., W. C. Hammond, and C. Kreemer (2018), Harnessing the GPS data explosion for interdisciplinary science, Eos, 99, https://doi.org/10.1029/2018EO104623.


Fig. 1. The Nevada Geodetic Laboratory processes data from a global network of about 17,000 geodetic GPS stations.



Fig 2. GPS stations (circles) and observed rate of vertical velocity of continental North America. Glacial isostatic adjustment dominates the field: uplift (red) in Canada and subsidence (blue) in the United States. California’s Central Valley and the Gulf Coast of Texas and Louisiana exhibit rapid subsidence. White regions are statistically consistent with zero motion with respect to Earth’s center of mass. Rates are plotted on a log scale and interpolated using the GPS imaging method of Hammond et al. [2016].


[June 18, 2018] New paper published on the August 24, 2014 M6.0 South Napa Earthquake

A new paper published by Nevada Geodetic Laboratory Graduate Student Meredith Kraner uses data from high‐precision continuous GPS stations to observe a 3 mm horizontal expansion of the Earth's crust prior to and in the vicinity of the August 2014 M6.0 South Napa earthquake. The study is a collaboration with William Holt from Stony Brook University, and Adrian Borsa from Scripps Institution of Oceanography at UC San Diego. The analysis looks at eight years of continuous GPS data leading up to the earthquake and finds that this pattern of horizontal crustal extension repeats every summer. The effect releases pressure on faults in the West Napa fault system, making them more likely to slip during the summer months. We speculate that large seasonal variability in the amount of groundwater in the Sonoma and Napa Valley subbasins may contribute to the observed changes.

Read more in the paper, which has been published in the Journal of Geophysical Research, Solid Earth and is available online
Time series of dilatational strain and Coulomb stress

Also see features from the AGU, AP news, KCBS radio, and Live Science.


[June 14, 2018] Pause in NGL Solutions For IGS14 Upgrade

Owing to the need to transition to IGS14 products as mandated by JPL, our final solutions will cease to be updated with new data until hardware, software, processing and data products systems are updated by sometime later this summer. NGL rapid and ultra-rapid solutions are already in IGS14 and will continue to be available. We are sorry for the inconvenience.


[May 8, 2018] New paper published on glacial isostatic adjustment across North America

The theory of plate tectonics says that tectonic plates move as rigid blocks along the Earth’s surface and that the Earth’s crust should only deform at the boundary between plates. However, the recent explosion in the number of high-precision Global Positioning System stations has allowed us to capture some subtle deformation patterns inside the North American plate that only became apparent by a very careful analysis of the relative motions between thousands of stations. We found that most of the plate is moving at 1-2 mm/yr towards central Canada. Consequently, around most of Canada there is a zone where the crust is contracting. Within Canada, the crust is extending outward and is moving upward rapidly. These patterns can be explained by the process of the crust and mantle still rebounding from a time when it was covered by a thick ice-sheet about 16,000 years ago. The fact that this causes the land to move towards the former ice sheet is an unexpected result that will be useful in understanding the relaxation properties of the underlying mantle. Moreover, we found that earthquakes inside the North American plate do not occur where we see the crust deform, which leaves these events still enigmatic.

The paper is available with open access.

See the UNAVCO Science Snapshot


In the above figure dilatational strain rate with blue and red colors are contractional and extensional, respectively. Results are only shown for dilatation rates that are larger than twice their standard deviation. Superimposed are selected velocities in a reference frame which has the area-weighted mean rotation for the entire plate (i.e., the plate’s net rotation) subtracted from the velocities in the original IGS08 reference frame.


[May 5, 2018] M6.9 Earthquake during volcanic eruptions near Leilani, HI

Yesterday, while volcanic eruptions occurred near the Kilauea East Rift Zone and Leilani, HI, a magnitude 6.9 earthquake occurred in the shallow crust. NGL processes openly available GPS data from continuously operating stations in the area using JPL's GIPSY software and rapid orbit products. Using 5 minute position time series that are automatically produced in our system we were able to estimate coseismic offsets from 57 stations near the epicenter. Many of these stations are near the Kilauea rift zone. We produced a a table of preliminary displacements from these time series.

A figure of these offsets below shows the difference in positions of stations before and after the earthquake, with larger offsets near the event, getting smaller with distance from the epicenter (yellow star). The maximum displacement was 0.77 meters. Gradients in the displacements indicate general extensional strain across the volcanic rift zones.



Data were obtained from continuously operating GPS stations operated by the USGS Hawaiian Volcano Observatory, University of Hawaii, Stanford University, the Jet Propulsion Lab, U.S. Coast Guard, and Federal Aviation Authority.


[February 15, 2018] "GPS Imaging" One of the Most Downloaded JGR Papers in 2017

We were recently notified that our article "GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift" published in October 2016 was one of the top 10 most downloaded papers in the Journal of Geophysical Research - Solid Earth in 2017! As of year-end 2017 the article received 1456 downloads.

The article is available with open access here: link to JGR.


[January 24, 2018] Update on the M7.9 Alaska Earthquake (see previous story below)

Data from many GPS stations have arrived since the earthquake and these have been processed at NGL using rapid orbits from JPL. We used these data to make 24 hour sample rate time series and estimate coseismic offsets from the difference between the new position and the median position from 10 days before the event. The figure shows that the displacement pattern is consistent with what was found earlier using ultra-rapid orbits. The data now are more numerous and have much smaller uncertaintes. We find that measurable displacement consistent with earthquake deformation is noticeable at many stations over a great distance. For example, INVK which is over 1500 km northeast of the epicenter in Canada's Northwest Territories, appears to have moved several mm to the southwest. Selected station names are given in the figure, offsets with large uncertainites were omitted.


The plot was made using this table of preliminary coseismic offsets.

[January 23, 2018] Massive earthquake offshore southern Alaska

The figure below shows very preliminary coseismic offsets from the January 23, 2018 M7.9 earthquake offshore southern Alaska. These are estimated from 5 minute sample rate GPS time series obtained using ultra-rapid orbit products from the Jet Propulsion Lab, obtained within 15 hours of the event. Only offsets with uncertainties (not shown) less than or equal to 10 mm are included. All resulting offsets are less than 13 mm and so are on the edge of significance. However, the pattern of horizontal motion is consistent with predictions of shallow strike slip event, with southwest displacement in the event’s northeast quadrant and west-northwest displacement in its northwest quadrant.


University of Nevada, Reno
Last edited 28 September 2022.