Asian Surveying & Mapping
Breaking News
Launch of Australia’s 1st orbital rocket, Gilmour Space’s Eris-1, delayed again
Update for 6:15 p.m. ET on July 1: Gilmour Space...
SAASST, UAE Space Agency strengthen scientific partnership
SHARJAH- Prof. Hamid M.K. Al Naimiy, Director of the...
Shubhanshu Shukla to speak to students and ISRO scientists this Friday
Indian astronaut Shubhanshu Shukla will interact with school students...
ISRO hands over 10 advanced technologies to Indian firms in major push for space commercialisation
The Indian Space Research Organisation (ISRO) has transferred ten...
DIGIPIN Launched: India Embraces Geospatial Precision in Digital Addressing
IIT Hyderabad (IITH), in partnership with the Department of...
HAL to build, market Isro’s SSLV in landmark deal
New Delhi, Jun 20: In a historic move for...
Taiwan developing space capabilities for all-weather imaging
TAIPEI (TVBS News) — Taiwan is advancing its space...
Honda hails successful test of reusable rocket as it looks to get into the space business
Tokyo — Japan's second-biggest carmaker, Honda, has successfully tested...
China’s space program provides larger platform for broader international cooperation
BEIJING -- Experts from China's manned space program said...
India To Launch $1.5 Billion Joint Earth Mission With NASA In July
National Aeronautics and Space Administration (NASA) and the Indian...

Protecting against flooding on islands requires reliable measurements of how much the ground is sinking and where, noted Jeanne Sauber, a geophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “You need to know in detail where the land is going down the fastest,” she said. Sauber and several NASA colleagues are combining remote-sensing tools to figure that out. 

Historically, subsidence measurements on small tropical islands have been difficult to make for two reasons. Islands often have few resources for acquiring detailed measurements at the land surface, and dense midday clouds and vegetation can make good satellite data difficult to get. 

Using the island of Tutuila in American Samoa as an example, a team of NASA scientists published a study in 2022 on how to better map ground changes on earthquake-prone islands. They found that using a combination of satellite and ground-based observations could result in a more-nuanced and comprehensive map.  

In the past, scientists had used data from two points of measurement on Tutuila: a GPS station and the island’s one tide gauge. They typically coupled those points with satellite altimetry, which allows scientists to broadly monitor the surface height of the ocean. But these data provided only a limited picture.  

In the study, the researchers added InSAR, or interferometric synthetic aperture radar, which allowed them to see where the ground was changing. InSAR is a technique that involves comparing satellite radar images of the same area collected at different times to spot movement on Earth’s surface and track changes in ground height. 

The study found that Tutuila sank an average of 0.24 to 0.35 inches (6 to 9 millimeters) per year between 2015 and 2022 compared to 0.04 to 0.08 inches (1 to 2 millimeters) per year before a 2009 earthquake. The highest rates of sinking occurred right after the earthquake, especially along the coastlines. 

Click here for more information. 

Image Credit: NASA Earth Observatory/Lauren Dauphin