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.

Yunnan, China Earthquake Epicenter

On August 3, 2014, a magnitude 6.1 earthquake struck in southern China's Yunnan province, toppling thousands of homes and causing numerous casualties. Hardest hit was Zhaotang City, located 18 miles (29 kilometers) east of the epicenter. This temblor was more damaging than a similar one two years earlier in the same region. The region where the quake occurred is shown in this perspective view from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft. It depicts vegetation in shades of red. The image looks toward the northwest and was acquired March 16, 2009. The star indicates the quake's epicenter location at 27.2 degrees north, 104.4 degrees east.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

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.

Flinders Ranges, Australia

This image from Japan’s ALOS satellite shows part of the Flinders Ranges in South Australia, about 500 km north of Adelaide.

The area pictured is between Flinders Ranges National Park to the south, Vulkathunha-Gammon Ranges National Park to the north and Lake Frome due east (none of which is pictured).

The curving structures that dominate this image are part of a larger geosyncline – a subsiding linear trough in Earth’s crust – that includes the Flinders Ranges. The geosyncline consists of sedimentary rocks in a basin that were folded about 500 million years ago and have been eroded to the current landscape. In this image, the different colors show the different layers of rock.

Some of the oldest fossilised animal life have been found in parts of the Flinders Ranges.

Running up the middle of this image is a long, narrow gorge – typical of the ranges.

Along the right side of the image, the terrain is flat with a long, straight road running north–south. Numerous creeks appear like veins across the entire image.

The Flinders Ranges is one of Australia’s most seismically active regions, with numerous small earthquakes recorded every year.

Japan’s Advanced Land Observation Satellite captured this image on 3 January 2009. ALOS was supported as a Third Party Mission, which means that ESA used its multi-mission ground systems to acquire, process, distribute and archive data from the satellite to its user community.

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

Image credit: JAXA/ESA

Gravity Scar from the March 2011 Japanese Earthquake

Changes in Earth’s gravity field resulting from the earthquake that hit Japan on 11 March 2011 (mE=10-12s-2). A combination of data from ESA’s GOCE mission and the NASA–German Grace satellite, shows the ‘vertical gravity gradient change’. The 'beachball' marks the epicenter.

Image credit: DGFI/TU Delft

Pakistan Epicenter

On September 24 at 11:29 GMT, a magnitude 7.7 earthquake struck in south-central Pakistan at a relatively shallow depth of 20 kilometers. The earthquake occurred as the result of oblique strike-slip motion, consistent with rupture within the Eurasian tectonic plate. Tremors were felt as far away as New Delhi as well as Karachi in Pakistan. Even though the immediate area to the epicenter is sparsely populated, the majority of houses are of mud brick construction and damage is expected to be extensive. The perspective view, looking to the east, shows the location of the epicenter in Pakistan's Makran fold belt. The image is centered near 27 degrees north latitude, 65.5 degrees east longitude, and was acquired December 13, 2012.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Istanbul, Turkey

Istanbul and the surrounding area in northwestern Turkey are captured in this image acquired by Envisat’s MERIS instrument on 9 June 2011. To the north is the Black Sea, which connects to the Sea of Marmara (center) via the Bosphorus strait. The Dardanelles strait connects the Marmara to the Aegean Sea (lower left corner). Turkey's largest city, Istanbul, is near the center of the image at the Bosphorus strait. Istanbul straddles two continents (Europe and Asia), making it a true meeting place of the East and the West.

Turkey’s location makes it vulnerable to earthquakes, with the 1000 km-long North Anatolian fault just 15 km south of Istanbul. Because earthquakes can suddenly render current maps out of date, satellite images are useful for updating views of how the landscape has been affected as well as creating reference cartography for emergency operations. In addition, before and after satellite images of the area enable authoritative damage assessment as a basis for planning remedial action.

Photo credit: ESA

Location of the April 20, 2013 Sichuan Earthquake

A powerful magnitude 6.6 earthquake struck Sichuan Province in southwest China on April 20, 2013, killing scores and injuring thousands, according to BBC News. Villages and roads near the epicenter were left in ruins, hampering rescue efforts. The earthquake occurred along the same fault that ruptured in 2008, killing tens of thousands and leaving some 5,000,000 people homeless. This perspective image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft, acquired in 2003, highlights the epicenter of the new earthquake. Vegetation is displayed in red; clouds and snow are in white.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Location of April 9 Iranian Earthquake

On April 9, 2013 at 11:52 GMT, a magnitude 6.3 earthquake hit southwestern Iran's Bushehr province near the town of Kaki. Preliminary information is that several villages have been destroyed and many people have died, as reported by BBC News. This perspective view of the region was acquired November 17, 2012, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft. The location of the earthquake's epicenter is marked with a yellow star. Vegetation is displayed in red; the vertical exaggeration of the topography is 2X. The image is centered near 28.5 degrees north latitude, 51.6 degrees east longitude.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Japan Earthquake Sensed by GOCE

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New studies have revealed that the massive earthquake that hit Japan on 11 March 2011 was also felt in space by ESA’s GOCE satellite. The massive earthquake sent ripples of sound – called infrasound – upwards through the atmosphere. These sound waves caused changes in air density that were detected by ESA’s GOCE gravity satellite as it crossed the wavefront.

Read full article: GOCE the First Seismometer in Orbit.

Video credit: ESA/IRAP/CNES/TU Delft/HTG/Planetary Visions

Japanese Earthquake Sensed from Space

The animation shows how the massive earthquake that hit Japan in 2011 caused ripples in the atmosphere. As sound waves from the earthquake traveled upwards, they caused changes in air density that were detected by ESA’s GOCE gravity satellite as it crossed the wavefront.

Video credit: ESA/IRAP/CNES/TU Delft/HTG/Planetary Visions