Photon Phright-day: Ghost Islands

Remote, recently formed (via volcanic eruptions) oceanic islands in the deep ocean can be studied by satellite lidar altimetry as ICESat2 has been doing, but especially with the satellite lidar bathymetry of the shallows where even ship-based sonars cannot go due to shallow, rough waters.

At Hunga Tonga Hunga Ha’apai (HTHH), the interior crater lake probably represents a vent complex for the tuff cone volcano that erupted over about one month in late 2014 into January 2015, forming the first “surtseyan” island that has survived for more than one year in more than 50 years.

This crater lake can now be explored via ICESat-2 satellite lidar bathymetry using precision-targeted transections that can show submarine topography to depths greater than 10 meters.

Our raft-based low-resolution sonar sounder depth readings from October 2019 SEA/NASA field expedition to HTHH suggest max depth are 12-15 meters with 1-2 meter vertical errors on these values.

The high precision ICESat2 lidar bathymetry measured depths of greater than 10 meters on the inner crater walls and over time could develop a map of bathymetric points to fully characterize the crater without requiring costly and logistically complex field operations at the remote island. ICESat2’s agility in measuring uniquely dynamic and sometimes short-lived phenomena is unique and showcases its contribution to Earth sciences priorities in this era of climate change and sea-level rise.

More on ICESat-2: https://nasa.gov/icesat2

Video credit: NASA's Goddard Space Flight Center

Ryan Fitzgibbons (KBRWyle)
Lead Producer
Lead Editor

James Garvin (NASA GSFC)
Lead Scientist
Lead Interviewee

Lori Magruder (University of Texas at Austin)
Project Support

Aimée Gibbons
Project Support

Cindy Starr (GST)
Lead Data Visualizer

Music: "Murder Victim," "City of Ghosts," Universal Production Music

HTHH island evolution research since 2015 (RRNES supported) by James B. Garvin and Dan Slayback of NASA GSFC. Experimental raft-towed sonar (LOWRANCE) by SEA students and enabled by Columbia Univ. Prof. Vicki Ferrini (Oct. 2019). Additional HTHH remote sensing from Maxar WorldView and CSA’s Radarsat-2 satellites (since 2015 for HTHH). Special thanks to Prof. Lori Magruder of UTx (CSR) for processing so adeptly the ICESat-2 lidar bathymetry. Permission by Kingdom of Tonga to conduct research into the evolution of HTHH as Earth’s newest land.

This video can be freely shared and downloaded at https://svs.gsfc.nasa.gov/13301. While the video in its entirety can be shared without permission, the music and some individual imagery may have been obtained through permission and may not be excised or remixed in other products. Drone footage used with permission by Dave Sheen and Captain Chris Nolan. Additional volcano stock footage obtained with permission from pond5. Specific details on such imagery may be found here: https://svs.gsfc.nasa.gov/13301. For more information on NASA’s media guidelines, visit https://nasa.gov/multimedia/guidelines.

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