Geodetic Science Snapshots - Human Dimensions

An 86-floor tall, steel-sculpted concrete building in Kuwait was shaken by a moment magnitude 7.3 earthquake far away at the Iran-Iraq border. The building’s shaking was captured by GPS sites, on the top of the building, and others near ground level. The ground shook with amplitudes of about 40 millimeters while the building shook up to 160 millimeters. Such observations can help to understand a building’s response to an earthquake and to improve building design in response to large stresses.

The National Earthquake Information Center (NEIC) is responsible for responding to earthquakes around the world. The expansion of Earth imaging satellites has expanded capabilities for geodetic observations and satellite imagery to describe earthquakes and their impacts. NEIC can integrate satellite imagery into earthquake information products for public awareness.

Combining geodetic and seismic observations can reduce the amount of time needed to assess the tsunami intensity generated by a large magnitude thrust fault earthquake along a subduction zone. Through retrospective analysis of four tsunamigenic large earthquakes in Japan and Chile, the tsunami potential at the local coast was estimated within less than 2 minutes.

Long-term records from GPS stations along the Atlantic Coast of North America show long term subsidence due to geologic adjustments and short term subsidence due to human-related groundwater extraction. These measurements are critical for understanding water use, sediment structure and sea level rise.

Estimates of the probabilities of a magnitude greater than 9.0 earthquake for the Aleutian Islands are about 6.5 to 12 percent over the next 50 years. Such an event poses obvious earthquake and tsunami risks for Alaska and tsunami risks for western North America and Hawaii.

Vertical motions measured by GPS ground stations can be used to track water loads related to precipitation in Ethiopia and Eritrea. The network monitors the seasonal East African monsoon and a smaller regional rainy season. The GPS network is an effective water monitor for the region, where most of the population is agriculture-based.

Eight years of observations of millimeter-level vertical surface changes from a dense network of Global Positioning System (GPS) receivers in the Pacific Northwest tracks a fluctuating water load due to varying precipitation. The observations track seasonal variations (i.e., more rain or snow in the fall and winter) and the drought of 2008-2010.

The Plate Boundary Observatory in the western United States is being used as a hydrological monitor. From 2013-2014, the western U.S. lost about 240 gigatons of water, equal to the amount of annual ice loss in Greenland.

Analysis of GPS stations, many that are part of the Plate Boundary Observatory, reveals uplift of the California Coast Ranges and Sierra Nevada Mountains. Much of this uplift comes from groundwater depletion for irrigation. These changes may increase the rate of seismicity on the San Andreas Fault.

About 900 GPS stations, most of which are part of the Plate Boundary Observatory in the western United States, recorded the Earth’s surface response to snow and rain loading. The analysis indicates the seasonal water storage in the mountains in California and shows another way to use GPS for water resource management.

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.

The damaging March 11, 2011 Tohoku earthquake caused significant tsunami waves that were recorded on videos by eyewitnesses. Two survivor videos from building rooftops at Kesennuma Bay were combined after the catastrophe and compared with on site terrestrial laser scans, using ground-based LiDAR.

An unexpected landslide could create a disaster for the town of Cerce del Cielo in Puerto Rico, especially if it cuts off access to the only road out of town.

Kilauea Volcano has been erupting through the spatter cone Puʻu ʻŌʻō since 1983 on the Big Island of Hawai’i. It has been an exciting, dynamic eruption, ranging from dramatic fissure and lava fountains, to lava streams oozing into the steaming ocean. It has also been destructive, destroying the towns of Kalapana and Kaimū in 1990.