Ground Deformation from the South Napa Earthquake

NASA’s Jet Propulsion Laboratory, Pasadena, California, has been monitoring active earthquake faults in California with a number of remote sensing and ground-based techniques. One such technique is the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) instrument, which has been in use since 2009. UAVSAR is an L-band Interferometric Synthetic Aperture Radar instrument that flies mounted underneath a NASA C-20A Earth science research aircraft from NASA’s Armstrong Flight Research Center in Edwards, California. UAVSAR is able to detect minute changes in Earth’s surface that occur over time between flights of the instrument.

UAVSAR has monitored much of California’s seismically active regions including the Napa area about every six months since November 2009. The temporal history is key to identifying and understanding change when an event, such as an earthquake occurs. A comparison of data collected May 29, 2014, three months before the earthquake, and data collected August 29, 2014, five days after the magnitude 6.0 South Napa earthquake on August 24, 2014, determined that the earthquake surface rupture was more complex than originally anticipated with motion on multiple strands of the fault near the earthquake’s epicenter. The colors in the image represent the amount of ground motion between the two flights in the direction from a point on the ground to the instrument, which flies at an altitude of 41,000 feet (12,497 meters). Each colored contour, or fringe, of the image represents 4.7 inches (12 centimeters) of ground displacement toward or away from the instrument. These preliminary results indicate that several inches/centimeters of horizontal slip occurred on the various strands of the fault. In addition, linear discontinuities in the colored zones indicate locations where surface rupture is highly likely and these are of profound concern. The exquisite detail of the UAVSAR imagery provides local, state and federal agencies with the exact location of the fault traces that shifted during the earthquake and how they relate to levees, buildings, roads, and other vital infrastructure, as well as to help provide a fundamental understanding of earthquakes processes.

Further analyses of UAVSAR data will reveal how deep under Earth’s surface the faults slipped and the amount of the slip. Initial GPS analyses (yellow arrows), indicate an average slip of nearly 23.6 inches (60 centimeters) along a 9.3-mile-long (15-kilometer) fault, which is equivalent to a magnitude 6.1 earthquake, suggesting that additional quiet (non-shaking) slip occurred along the fault following the main earthquake.

Image credit: NASA/JPL-Caltech/ASI/Google Earth

Note: For more information, see PIA18798: NASA Analyses of Global Positioning System Data and Italian Radar Satellite Data Reveal Napa Quake Ground Deformation and NASA Research Aids Response to California Napa Quake.

Norwegian Fringes

The animation, which is based on an interferogram generated with two radar images captured by Sentinel-1A in ‘Interferometric Wide-Swath’ mode on 11 and 23 August 2014, mainly shows topography around the northern coast of Norway. Although Sentinel-1A is still being commissioned, this new result demonstrates how useful it will be to map the shape of the land and monitor ground movement. Synthetic aperture radar interferometry – or InSAR – is a technique where two or more satellite radar images acquired over the same area are combined to map topography and detect surface changes. Small changes on the ground cause changes in the radar signal phase and lead to the rainbow-colored fringes of an ‘interferogram’. In this case, the animation denotes differences in topography.

Since the area around the Lyngen Alps is particularly prone to landslides, it is closely monitored. Large landslides that suddenly shift rock into the sea could potentially create tsunami-like waves. In 1810, such a wave destroyed a village, and, history shows that this kind of natural disaster occurs a couple of times every 100 years in Norway. InSAR is an important tool used by the Norwegian authorities to map rockslide hazards nationwide. The unprecedented coverage offered by the Sentinel-1 mission will significantly increase the value of InSAR data for this purpose.

Video credit: Copernicus data (2014)/ESA/Norut–SEOM Insarap study (video animation data: Norwegian Mapping Authority and NASA)

Note: For more information, see Norway Relief. For similar images, one featuring northwestern Italy and part of Corsica and the other featuring Mount Etna on the island of Sicily, see New Views From Sentinel-1A and Etna Slopes, respectively.

Rub’ al Khali Desert

Rolling sand dunes in the expansive Rub’ al Khali desert on the southern Arabian Peninsula are pictured in this radar image from the Sentinel-1A satellite.

Rub’ al Khali – also known at the ‘Empty Quarter’ – is part of the greater Arabian Desert. Its sand dunes reach up to 250 m in height and in some areas are interspersed with hardened flat plains, evident at this bottom half of this image. These plains are what is left of shallow lakes that existed thousands of years ago, formed by monsoon-like rains and runoff.

Today, the region is considered to be ‘hyper-arid’, with precipitation rarely exceeding 35 mm a year and regular high temperatures around 50°C.

Rub’ al Khali has experienced major desertification over the past 2000 years. Until about the year 300 AD, trade caravans crossed what is today an impassable wasteland.

In the upper part of this image, we can see a road snaking through the remote desert and leading to Kharkhir (not pictured), a Saudi village near the border with Yemen.

Sentinel-1 is a two-satellite radar mission for Europe’s Copernicus program. The first satellite of the pair, Sentinel-1A, was launched in April. The satellite is still being commissioned to prepare for routine operations.

This image is featured on the Earth from Space video program.

Image credit: ESA

Towing the Costa Concordia

This Sentinel-1A image was acquired on 26 July 2014 over the coast of northwestern Italy while the Costa Concordia cruise ship (enlarged) was being towed towards the city of Genoa.

The ship capsized near the island of Giglio in January 2012. Following more than two years of salvage operations, the ship began its final journey under tow on 23 July 2014, arriving at the port of Genoa four days later.

During and after the towing, satellite radar images – such as the one here – were analyzed, with the technical support of the European Commission’s Joint Research Centre. This was done for scientific research purposes to assess the Sentinel-1A and other satellite radar images for pollution and ship traffic.

Sentinel-1A is the first satellite launched for Europe’s Copernicus environment monitoring program. Surveillance of the marine environment, including oil-spill monitoring and ship detection, is one of the mission’s main tasks. Although Sentinel-1A is still being commissioned to prepare for routine operations, early images like this demonstrate the value of its radar vision.

The Copernicus program also supported recovery operations of the Costa Concordia. Learn more.

Image credit: ESA

Rio de Janeiro and Guanabara Bay

Guanabara Bay in southeast Brazil is pictured in this image from the Sentinel-1A satellite.

The city of Rio de Janeiro lies on the western banks of the bay and along the Atlantic coast to the south. Rio is connected to the city of Niterói on the east side of the bay by a large bridge which appears as a dotted straight line. To the north, we can see radar reflections from large ships.

Governador is the largest island in Guanabara Bay, and the site of Rio de Janeiro’s main airport. The runways appear as dark lines.

Part of Rio de Janeiro was designated a UNESCO World Heritage Site in 2012 under the category of ‘cultural landscapes’. The Tijuca National Park – the mountainous area in the lower-left – is a hand-planted rainforest covering more than 30 sq km. The iconic statue of Christ the Redeemer stands at the eastern end of the forest, overlooking the city from the peak of the 700 m-high Corcovado mountain.

Zooming in above the mountains, the two circular structures are large stadiums. The one to the right is Estádio do Maracanã, where the final match of this year’s World Cup will take place on Sunday.

At the bottom-center part of the image, the curved coast of the famous Copacabana is visible, while Sugarloaf mountain sits at the mouth of the bay.

This image, also featured on the Earth from Space video program, was acquired on 13 May by Sentinel-1A’s radar working in 'dual polarization'. The radar gathers information in either horizontal or vertical radar pulses, and colors were assigned to the different types.

Image credit: ESA

Mount Pinatubo, Philippines

This image from the Sentinel-1A radar satellite on 6 June shows part of the Philippine island of Luzon with Mount Pinatubo.

This active volcano experienced a major eruption on 15 June 1991 that injected more particulate matter into the atmosphere than any eruption since Krakatoa in 1883. In the months following, aerosols formed a layer of sulphuric acid haze around the globe, ozone depletion increased and global temperatures dropped by about 0.5°C.

In the upper-central part of the image, the dark area is Lake Pinatubo, which formed in the summit crater after the 1991 eruption. The water level has been rapidly increasing since its formation, putting pressure on the crater walls, which threaten to collapse and cause flash floods. The Philippine government has taken measures to alleviate the pressure with controlled draining.

South of Lake Pinatubo near the center of the image is Mapanuepe Lake, which also formed as a result of the 1991 eruption. When mud mixed with water and volcanic rock fragments flowed down from Pinatubo, it blocked the drainage of the river. The valley – including the settlements – was inundated. These mud and volcanic debris flows are still visible reaching west towards the South China Sea.

Other features visible in this image include the bright radar reflections from a shipyard on the Subic Bay to the south, and the vast expanse of aquaculture on the edge of Manila Bay in the lower-right corner.

Sentinel-1A was launched on 3 April, and is the first in a fleet of Sentinel satellites developed for Europe’s Copernicus environment monitoring program. Although the satellite is still being commissioned, images like this early example illustrate the kind of data the mission will provide.

This image is featured on the Earth from Space video program.

Image credit: ESA

Paraná River Flooding

Map of flood extent on the Paraná River in northern Argentina near the border with Paraguay. Water bodies and surrounding wetland areas observed by the German TerraSAR-X satellite on 11 June 2008 are colored blue, while recently flooded areas imaged by Sentinel-1A on 15 June 2014 appear in red.

This map was produced following an activation of the International Charter Space and Major Disasters. More information.

The radar on Sentinel-1 is able to ‘see’ through clouds, rain and in darkness, making it particularly useful for monitoring floods. Images acquired before and after a flood offer immediate information on the extent of inundation and support assessments of property and environmental damage.

Image credit: ESA/DLR/CAEARTE/CONAE ML

Lake Constance

The freshwater Lake Constance in Central Europe is pictured in this image from the Sentinel-1A satellite.

Formed by the Rhine Glacier during the last Ice Age, it covers an area of about 540 sq km and is an important source of drinking water for southwestern Germany.

The lake has shorelines in three countries: Germany to the north, Switzerland to the south and Austria at its eastern end. Over the water body, however, there are no borders because there is no legally binding agreement on where they lie.

In the lower-right, we can see where the Rhine river flows into the lake from the south, which then flows out of the lake to the west (left). This and other rivers carry sediments from the Alps, extending the coastline and decreasing the lake’s water depth.

The runways of Germany’s Friedrichshafen Airport are visible in the right section of the image. The Aviation & Aerospace Museum is nearby.

This image was acquired on 10 May in ‘interferometric wide swath mode’ and in dual polarization.

The radar instrument gathers information in either horizontal or vertical radar pulses, and colors were assigned to the different types. In this image, buildings generally appear pink, while vegetation is green. Areas with lowest reflectivity in all polarizations appear very dark, like the water.

Sentinel-1A’s radar is still being calibrated following its 3 April 2014 launch, but early images like this give us a glimpse of the kind of operational imagery that this mission will provide for Europe’s Copernicus environmental monitoring program.

This image is also featured on the Earth from Space video program.

Image credit: ESA

Poyang Lake, China

Image of China’s Poyang lake from the synthetic aperture radar (SAR) on the Sentinel-1A satellite, acquired on 12 May 2014 in dual polarization. The radar gathers information in either horizontal or vertical polarizations, shown here as a composite (HH in red, HV in green and HH-HV in blue).

Poyang is just one of the many project areas of the collaborative Chinese-European Dragon Program, which marked its ten-year anniversary this week. Read more.

Image credit: ESA

Ubinas Volcano, Peru

This false-color image of Peru's Ubinas volcano was acquired on April 14, 2014, by NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar, or UAVSAR. Located about 100 miles (160 kilometers) from the city of Arequipa, Ubinas is Peru's most active volcano.

UAVSAR flew exactly the same flight path over Ubinas in 2013. By combining the images from the two years, researchers will produce detailed maps of surface motions that can improve models of volcanic deformation.

Image credit: NASA/JPL-Caltech

Athens, Greece

Sentinel-1A radar acquisition from 22 April 2014 showing Greece’s Attica region, with mountainous areas and the capital and largest city of Athens near the center. In the water, different shades of blue indicate different types of sea surface, influenced by currents and waves. The image was acquired in ‘interferometric wide swath’ mode and with a dual polarization in VV and VH. Colors were assigned to different types of radar polarizations.

Image credit: ESA

Note: For more information, see Attica Peninsula, Greece.

Salar de Uyuni, Bolivia

This radar image is one of the first from the Sentinel-1A satellite, acquired on 20 April – less than three weeks after its launch on 3 April.

The image shows the Salar de Uyuni in Bolivia, which is the largest salt flat in the world.

Occupying over 10,000 sq km, the vast Salar de Uyuni lies at the southern end of the Altiplano, a high plain of inland drainage in the central Andes. Some 40,000 years ago, this area was part of a giant prehistoric lake that dried out, leaving behind the salt flat.

While the salt flat appears an almost homogenous white in optical satellite imagery, here we see it in shades of grey, and it looks almost like a lake. This has to do with how the radar signal reacts to different surfaces: areas where the radar signal is absorbed appear darker, while areas where the signal is reflected back to the satellite appear lighter. This gives Earth observation experts an indication of how rough or smooth the surfaces area, differences in salt density or even the presence of water.

But on the whole, the Salar de Uyuni is very flat, with a surface elevation variation of less than 1 m. This makes the area ideal for calibrating satellite radar altimeters – a different kind of radar instrument that measures surface topography. The future Sentinel-3 mission will carry a radar altimeter.

The surrounding terrain is rough in comparison to the vast salt flat and is dominated by the volcanoes of the Andes mountains forming part of the Pacific Ring of Fire.

Sentinel-1A is the first in the two-satellite Sentinel-1 mission for Europe’s Copernicus program. Its radar data will be used for a variety of applications, including the surveillance of the marine environment, monitoring land-surface for motion risks, mapping for forest, water and soil management, and mapping to support humanitarian aid and crisis situations.

This image is featured on the Earth from Space video program.

Image credit: ESA

The Netherlands

This image over the west coast of the Netherlands is one of the early radar scans by the Sentinel-1A satellite, which was launched on 3 April.

The satellite’s advanced radar can provide imagery under all weather conditions and regardless of whether it is day or night. It can scan Earth’s surface in a range of different modes, enabling it to monitor large areas in lower resolution or to zoom in on a smaller region for a sharper view.

One of the many application areas of the data will be the surveillance of the marine environment, including monitoring oil spills and detecting ships for maritime security, as well as measuring wave height.

In this image, we can clearly see radar reflections from the ships at sea, appearing like stars in a night sky. The two collections of ‘stars’ are reflections from large-scale offshore wind farms, used to generate electricity.

Other visible features include the city of Amsterdam on the center-right side of the image, and the runways of the nearby Schiphol airport. In the lower part of the image we can see the city of Rotterdam, with Europe’s largest port extending to the left.

Sentinel-1’s radar will also be used for monitoring changes in agricultural land cover – important information for areas with intensive agriculture like the Netherlands.

This image, also featured on the Earth from Space video program, was acquired on 15 April with the radar operating in ‘stripmap mode’, which provides coverage at a resolution of about 10 m.

Sentinel-1A is the first in a fleet of satellites being developed for Europe’s Copernicus environmental monitoring program. The satellite is not yet in its operational orbit, but early images like this have given us a taste of what’s to come.

Image credit: ESA

Brussels, Belgium

Acquired on 12 April 2014 at 17:18 GMT (19:18 CEST), just nine days after launch, this first image from Sentinel-1A captures Brussels and surrounds in Belgium. It was acquired in the satellite’s ‘strip map’ mode, which has a swath width of 80 km, and in dual polarization. The image also shows a more detailed view of the city in the ‘zoom in’. Antwerp harbour is also visible in the top left. The green colors correspond to vegetation, red–blue to urban areas, white to high-density urban areas and black to waterways and low-reflective areas such as airport runways.

Image credit: ESA

Flooding from the Zambezi River in Namibia

Acquired on 13 April 2014 at 03:50 GMT (05:50 CEST) by Sentinel-1A, this image shows the extent of flooding in the Caprivi plain from the Zambezi River in Namibia. Sentinel-1A acquired this image in its main ‘Interferometric Wide Swath’ mode with a swath width of 250 km and in dual polarization. Victoria Falls is also featured in the image, further east along the Zambezi River. The image was downloaded two hours after acquisition and the resulting products were available in less than an hour. Such images can be taken in adverse weather conditions and during the dark, demonstrating the value of Sentinel-1’s radar vision.

Image credit: ESA

Pine Island and Thwaites Glaciers, Antarctica

Acquired on 13 April 2014 at 09:03 GMT (11:03 CEST) this image covers parts of Pine Island Glacier and Thwaites Glacier in West Antarctica. This image is among the first from Sentinel-1A, which was launched on 3 April. It was acquired in ‘Interferometric Wide Swath’ mode with a swath width of 250 km and in single polarization. With Pine Island Glacier in a state of irreversible retreat, the Sentinel-1 mission is set to be an excellent tool for monitoring such glaciers as well as for providing timely information on many other aspects of the polar regions, such as sea ice and icebergs.

Image credit: ESA

Antarctica Peninsula

Acquired on 13 April 2014 at 23:57 GMT (14 April at 01:57 CEST) by Sentinel-1A, this image shows a transect over the northern part of the Antarctica Peninsula. It was acquired in the satellite’s ‘strip map’ mode with a swath width of 80 km and in dual polarization. The colors indicate how the land, ice and water reflect the radar signal differently.

Image credit: ESA

Liftoff of Sentinel-1A

Cameras mounted on the Soyuz Fregat upper stage that sent Sentinel-1A into space on 3 April 2014 captured this footage from liftoff to separation.

The 2.3-ton satellite lifted off on a Soyuz rocket from Europe’s Spaceport in Kourou, French Guiana at 21:02 GMT (23:02 CEST). The first stage separated 118 sec later, followed by the fairing (209 sec), stage 2 (287 sec) and the upper assembly (526 sec). After a 617 sec burn, the Fregat upper stage delivered Sentinel into a Sun-synchronous orbit at 693 km altitude. The satellite separated from the upper stage 23 min 24 sec after liftoff.

Sentinel-1 is the first in the family of satellites for Europe’s Copernicus program. It carries an advanced radar to scan Earth’s surface in all weather conditions and regardless of whether it is day or night. This new mission will be used to care for many aspects of our environment, from detecting and tracking oil spills and mapping sea ice to monitoring movement in land surfaces and mapping changes in the way land is used.

Video credit: Arianespace/ESA/Roscosmos; Music written by M. Oldfield/copyright EMI Virgin

Update: A slightly longer version of the video can be found here: Onboard Cameras Show Full Launch and Separation of Sentinel-1A.

Surface Displacement Map for 28 March 2014 La Habra Earthquake

Scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, developed a model of the March 28, 2014, magnitude 5.1 La Habra, California earthquake, based on the distribution of aftershocks and other seismic information from the U.S. Geological Survey. This image shows what the earthquake may look like to an interferometric synthetic aperture radar, such as NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR).

The earthquake is believed to be associated with the Puente Hills Thrust fault, which zig-zags from Orange County northwest through downtown Los Angeles. The NASA model is based on a fault estimated to be 9 kilometers long, 5 kilometers deep and 3 kilometers wide. The modeled fault dips upward through the ground at a 60-degree angle, with one side of the fault moving at a slanted angle horizontally and vertically 10 centimeters relative to the other side. The model estimated the maximum displacement of Earth's surface from the quake at approximately 1 centimeter, which is at the threshold of what is detectable with UAVSAR. The region of ground displacement is indicated by the darker blue area located in the right center of the image.

In November 2008, NASA JPL scientists began conducting a series of UAVSAR flights over regions of Northern and Southern California that are actively deforming and are marked by frequent earthquakes. About every six months, the scientists precisely repeat the same flight paths to produce images of ground deformation called interferograms. From these data, 3-D maps are being created for regions of interest, including the San Andreas and other California faults, extending from the Gulf of California in Mexico to Santa Rosa in the northern San Francisco Bay.

UAVSAR, which flies on a NASA C20-A III aircraft from NASA's Armstrong Flight Research Center, measures ground deformation over large areas to a precision of 0.1 to 0.5 centimeters (0.04 to 0.2 inches).

By comparing the repeat-pass radar observations, scientists hope to measure any crustal deformations that may occur between observations, allowing them to 'see' the amount of strain building up on fault lines, and giving them a clearer picture of which faults are active and at what rates they're moving, both before earthquakes and after them. The UAVSAR fault mapping project is designed to substantially improve knowledge of regional earthquake hazards in California. The 3-D UAVSAR data will allow scientists to bring entire faults into focus, allowing them to understand faults not just at their surfaces, but also at depth. When integrated into computer models, the data should give scientists a much clearer picture of California's complex fault systems.

The scientists are estimating the total displacement occurring in each region. As additional observations are collected, they expect to be able to determine how strain is partitioned between individual faults.

The UAVSAR flights serve as a baseline for pre-earthquake activity. As earthquakes occur during the course of this project, the team is measuring the deformation at the time of the earthquakes to determine the distribution of slip on the faults, and then monitoring longer-term motions after the earthquakes to learn more about fault zone properties.

Airborne UAVSAR mapping can allow a rapid response after an earthquake to determine what fault was the source and which parts of the fault slipped during the earthquake. Information about the earthquake source can be used to estimate what areas were most affected by the earthquake shaking to guide rescue and damage assessment response.

The scientists now plan to acquire UAVSAR data from the region, possibly as soon as this week, and process the data to validate and improve the results of their model.

Image credit: NASA/JPL-Caltech/USGS/Google Earth

Note: For more information, see NASA Model Provides a 3-D Look at L.A.-area Quake.

Southwest Iran

This colorful radar composite image shows changes in large-scale agricultural plots in southwest Iran.

The individual images were acquired by the radar on Japan’s ALOS satellite on 16 November, 16 May and 1 October 2010. Combined, the different colors show changes in the fields – such as harvesting at different points on time.

The most prominent fields in this image each measure about 1 km across. To the lower right, the smaller structures are ponds for aquaculture. Important fish for inland fisheries include carp, roach and mullet.

Running through the center of the image is the Karun River. It is the country’s only navigable river, originating in the Zagros mountains and running its 720 km course southwest and into the Shatt al-Arab river, which then flows into the Persian Gulf.

Clusters of bright white radar reflections indicate the presence of buildings and other human-made structures, such as those seen in the middle of the blocks of fields and along the river.

On the center-right side of the image, we can also see dots of white, evenly dispersed in a single row east-to-west. These are reflections from towers holding power lines. While these structures are difficult to spot in optical imagery – like the satellite images on Google Earth – their reflectivity makes them more visible to radar.

This image is featured on the Earth from Space video program.

Image credit: JAXA/ESA