When Disasters strike, Satellites come calling

Huddled in an inconspicuous corner, eyes transfixed on their computer monitors, a group of young experts wait for satellite images to arrive. A disaster has just struck Indonesia, and the twin impact of the earthquake and the tsunami it triggered could be devastating. The initial ping about an impending disaster has proved true, and the International Disaster Charter has just been activated.

Five-thousand kilometers away from the disaster zone centered on Palu in Indonesia, the team of disaster experts has assembled at the Geoinformatics Center (GIC) of the Asian Institute of Technology (AIT) in Thailand. Having been nominated as the project manager under the Global Disaster Charter, they will be the single access point for satellite information that will start flowing from all over the world.

As images start arriving, the trickle of satellite data turns into a virtual flood as numerous satellites reorient themselves towards the disaster area and start beaming the latest images. As a member of the disaster team, Syams Nashrrullah has worked on disasters before. This is the third disaster charter activation in 2018, which included the floods in Japan, the earthquake in Lombok, and now the Sulawesi disaster.

Asked to compare the Lombok and the Sulawesi disasters, Syams says: “The scale was totally different. Sulawesi was not only a bigger disaster, but it combined both an earthquake and a tsunami.” Narrating the sequence of events, Syams reveals that the first major public release of satellite information was the image received from the Pleiades satellite. Working with the National Institute of Aeronautics and Space (LAPAN) and the Bandung Institute of Technology (ITB) in Indonesia, they processed and released the image, which proved a boon for aid and humanitarian relief workers and was quickly reproduced in dozens of news outlets and websites.

The satellite data generated by AIT and partner organizations was used by local governments and armed forces to conduct emergency rescue and relief operations. It also helped arrive at an initial estimate that close to 5,000 buildings and structures had suffered major damage, particularly in Palu (the estimate has now passed 8,000).

The data contained information up to a resolution of 50 centimeters and was the first publicly accessible set of images showing the extent of the damage. A comparison of the same area prior to and following the disaster was a telling example of how remote sensing now enables swifter and more efficient post-disaster management efforts. Shortly afterwards came another satellite image, and this provided even more detailed information. This Digital Globe image showed greater details and covered an even larger area. Nearly 500 such images arrived, and after initial screening, close to one-fifth were processed by AIT’s GIC courtesy of free satellite data supplied by numerous providers from all over the world.

This was the first step. A few days later, it was time for some ground-truthing. Among those stationed in the field to collect data and photographs was Dr. Firman Hadi, a research specialist at GIC. After waiting two days at the Mutiara airport, Firman joined a team of humanitarian aid workers for a 10-hour journey to Palu, the capital of Central Sulawesi Province. What greeted him was ruin, devastation, and the phenomenon of liquefaction at four locations — Petobo, Balaroa, Jono Oge, and Sibalaya. He spent six days taking photographs, geotagging images with locational data, adding the required geographical information to the photographs, and coordinating with local agencies to help assess damage to buildings.

A week later, a full-fledged web-based portal had been established. Based on a Geographical Information Systems (GIS) platform, the portal provides satellite data and analytics, which along with field data permit an assessment of damage to buildings and infrastructure. The new portal builds on the nearly 500 satellite images that were analyzed following the disaster, including the pre- and post-disaster images obtained by AIT from leading providers of satellite images worldwide to conduct an assessment of the damage caused. “The portal goes beyond the initial remote sensing assessment, since we have access to considerable field data,” says Dr. Manzul Hazarika, Director of GIC.

“Our new web-based GIS platform puts the number of damaged buildings at 8,128,” says Dr. Hazarika. It has village-level details of the damage, with Palu Barat (2,933 buildings) and Palu Selatan (2,258 buildings) accounting for most of the damage. Similarly, the team helped map losses in health facilities, educational buildings, government offices, and roads.

Still, there is a long way to go. “A damaged airport, impassable roads, and damaged power lines have hampered efforts to assist remote regions,” adds Dr. Hazarika. But satellite images help identify the roads that are damaged and suggest alternative routes that enable faster access.

The combined efforts of numerous research organizations, satellite agencies, universities, and research institutes provide a stellar example of how satellite images and remote sensing coupled with Geographical Information Systems have metamorphosed the entire gamut of disaster relief.

Published in ReliefWeb at this link: https://reliefweb.int/report/indonesia/when-disasters-strike-satellites-come-calling