Volcanic Studies and Disaster Response in Africa

Sentinel-1 CEOS-ARD gives insight into the extent and distribution of lava flows, helping researchers develop more accurate methods and models that will save lives.

Project Overview

Mount Nyiragongo, in the Democratic Republic of Congo, is an active volcano that last erupted on May 22, 2021, with fissures of the volcano sending lava to the airport in Goma and into the nearby towns. The eruption resulted in the deaths of at least 32 people and the evacuation of over 232,000 residents from the region.

The Mount Nyiragongo area is frequently covered by clouds, and hence only a limited ground surface can be discerned by optical or thermal imagery (e.g., Landsat, Sentinel-2) at any given time. However, the extensive new lava flow was clearly identifiable with radar data from Sentinel-1, which is now delivered as CEOS Analysis Ready Data (CEOS-ARD) through the Digital Earth Africa (DE Africa) platform.

Application & Platform

Digital Earth Africa (DE Africa) is a continental-scale Data Cube operating in the cloud. Digital Earth Africa makes Earth observation (EO) data free and accessible, delivering decision-ready products to the African continent. In addition to providing EO data and derived products, it is a processing and analysis environment that provides access to numerous services, tools, and capabilities to allow users to develop applications for research and societal benefit.

Sentinel-1 provides an unprecedented operational capability for intensive radar mapping of the Earth's surface, with increased revisit frequency, spatial coverage, and reliability, crucial for operational services which require long time series of radar data. The ability of radar data to ‘see’ through clouds makes the datasets critical for mapping and monitoring different phenomena such as lava flows, mudslides, floods, ground fissures, earthquakes, etc. Furthermore, Sentinel-1 is the only Synthetic Aperture Radar (SAR) satellite which provides data on a full, free, and open basis.

CEOS-ARD Usage

In partnership with Sinergise and the CEOS Systems Engineering Office (SEO), DE Africa developed the first Normalised Radar Backscatter (NRB) product to meet the CEOS-ARD NRB Product Family Specification. The Sentinel-1 RTC (Radiometrically Terrain Corrected) dataset is derived from Sentinel-1 GRD (Ground Range Detected) provided by the European Space Agency (ESA), who operates Sentinel-1. The DE Africa Sentinel-1 dataset is processed by Sinergise and stored in the cloud on the AWS S3 platform, sponsored by the Amazon Public Dataset Program.

The Sentinel-1 CEOS-ARD product is free and open and accessible via the DE Africa platform, a continental data cube, which provides various tools and services for big data analysis. The DE Africa team ensured the necessary data pipelines are in place to automatically process the data and provide access the CEOS-ARD product about a day after it is first acquired by the satellite.

Sentinel-1 CEOS-ARD is accessible to all users and can be explored through the Digital Earth Africa Sandbox or Map.

Impact

The 2021 Nyiragongo eruption provided an example use case for DE Africa Sentinel-1 CEOS-ARD. While the product was not available at the time of the event, by processing the historical images taken at that time, experts can analyse the images and develop methodologies that can be used in real time during future events. The pre-processed CEOS-ARD can be delivered quickly and allows non-EO experts to use the data, which is critical during a natural disaster. This facilitates quicker decisions and actions by emergency responders, potentially reducing the impact of volcanic eruptions on communities.

SAR images acquired after the eruption give insights into the extent and distribution of the lava flow, at never-before-seen angles and detail. This will help researchers develop more accurate methods and improve modelling of lava flow for future events, and hopefully save lives with more accurate warnings and alerts.

Future Developments

Some words from the DE Africa users and volcanologists applying the products.

Future direction of this Sentinel-1 RTC CEOS-ARD.

Technical Characteristics

CEOS-ARD Types: Normalised Radar Backscatter

Contributing Missions: Sentinel-1

Developing Agency: Digital Earth Africa (DE Africa)

Users: Digital Earth Africa (DE Africa)

Project website / more info: https://www.digitalearthafrica.org/

Points of contact for queries

Name
Digital Earth Africa
Email