Date of Images:

12/5/2021, 12/7/2021

Date of Next Image:

Unknown

Summary:

12/5/2021 (JAXA ALOS-2)

The map is derived from synthetic aperture radar (SAR) images acquired by the ALOS-2 satellites operated by the Japan Aerospace Exploration Agency (JAXA). The images were taken before (27 Oct 2019) and during (5 Dec 2021) the event. Analysed by the Earth Observatory of Singapore - Remote Sensing Lab (EOS-RS), in collaboration with NASA's Disasters Program and the Advanced Rapid Imaging and Analysis (ARIA) team at the Jet Propulsion Laboratory and California Institute of Technology.

This preliminary map shows areas that are likely affected by pyroclastic flows (shown by orange pixels of 25 m in size) in Eastern Java, Indonesia due to the eruption at Semeru volcano starting on 4 Dec 2021. It is validated using ground observations at Gladak Perak Bridge. This map should be used as a guidance to identify areas that are likely affected, and is less reliable over urban and vegetated areas. This map may contain any changes caused by previous eruptions in 2020.

12/7/2021 (Copernicus Sentinel-1)

The Earth Observatory of Singapore - Remote Sensing Lab (EOS-RS) created this Damage Proxy Map (DPM) depicting areas that are likely damaged by pyroclastic flows and lahars in Eastern Java, Indonesia due to the eruption of Semeru volcano starting on 4 Dec 2021. The map was derived from synthetic aperture radar (SAR) images acquired by the Copernicus Sentinel-1 satellites operated by the European Space Agency (ESA). The team compared the post-event image acquired on 7 Dec 2021 with pre-event images taken since 9 Aug 2021.

Suggested Use:

• JAXA ALOS-2: This preliminary map shows areas that are likely affected by pyroclastic flows (shown by orange pixels of 25 m in size) in Eastern Java, Indonesia due to the eruption at Semeru volcano starting on 4 Dec 2021. It is validated using ground observations at Gladak Perak Bridge. This map should be used as a guidance to identify areas that are likely affected, and is less reliable over urban and vegetated areas. This map may contain any changes caused by previous eruptions in 2020.

• Copernicus Sentinel-1: The color variation from yellow to red indicates increasingly more significant surface change. Preliminary validation was done by comparing with the media reports.

This damage proxy map should be used as guidance to identify damaged areas or areas affected by heavy volcanic ash fall, and may be less reliable over vegetated areas. For example, the scattered colored pixels over vegetated areas may be false positives, and the lack of colored pixels over vegetated areas does not necessarily mean no damage. This map is most sensitive to building damage and other large changes, but small-scale change or partial structural damage may not be detected by this map.

Satellite/Sensor:

Japan Aerospace Exploration Agency (JAXA) ALOS-2 PALSAR-2

Copernicus Sentinel-1 Synthetic Aperture Radar (SAR)

Resolution:

JAXA ALOS-2: 25 meters

Copernicus Sentinel-1: 30 meters

Credits:

Sentinel-1 data were accessed through the Copernicus Open Hub and AWS Open Dataset of Copernicus Sentinel-1 data for the Asia region (https://registry.opendata.aws/sentinel1-slc-seasia-pds). The product contains modified Copernicus Sentinel data (2021), processed by ESA and analyzed by the Earth Observatory of Singapore - Remote Sensing Lab (EOS-RS), using the Advanced Rapid Imaging and Analysis (ARIA) system originally developed at NASA's Jet Propulsion Laboratory, California Institute of Technology, and modified at EOS-RS.

The ALOS-2 data products are processed from original data products copyright (2021) by the Japan Aerospace Exploration Agency (JAXA) and analysed by the Earth Observatory of Singapore - Remote Sensing Lab (EOS-RS), in collaboration with NASA's Disasters Program and the Advanced Rapid Imaging and Analysis (ARIA) team at the Jet Propulsion Laboratory and California Institute of Technology.