RAPID survey of the bathymetry of Hunga Tonga-Hunga Ha’apai caldera

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RAPID Survey of the Bathymetry of Hunga Tonga-Hunga Haʻapai CalderaHunga Tonga-Hunga Ha’apai volcano in the Kingdom of Tonga in the SW Pacific Ocean north of New Zealand erupted very violently on January 14, 2022, sending an ash cloud ~44 km into the air and causing a tsunami up to 15 m high. The violent nature of the eruption makes it likely that the vent was very shallow, near the summit of the submarine volcano. The effects of the eruption on the seafloor are poorly understood and will be investigated in this joint US-New Zealand seagoing program. The expedition will use a small ship equipped with modern seafloor mapping equipment to map the changes the eruption made near the top of the submarine volcano at its summit. A short (~5 min.) video explaining the operations and scientific activities on the expedition will be produced and disseminated to the public on YouTube.Hunga Tonga-Hunga Ha’apai volcano in the Kingdom of Tonga in the SW Pacific Ocean north of New Zealand erupted very violently on January 14, 2022, sending an ash cloud ~44 km into the air and causing a tsunami up to 15 m high. The violent nature of the eruption makes it likely that the vent was very shallow, from a submarine caldera near the summit of the volcano. The effects of the eruption on the seafloor are poorly understood and will be investigated in this joint US-New Zealand seagoing program. A 28 m-long, shallow-draft New Zealand research vessel (R/V Kaharoa) equipped with modern seafloor mapping equipment will map the seafloor to determine changes caused by the eruption at the summit and flanks of the submarine volcano. The expedition will also make other geophysical measurements: 1) a towed magnetometer will measure the magnetic signature of the caldera; 2) a shipboard gravimeter will measure the gravity anomaly over the caldera; and 3) a Digital Optical Absorption Spectrometer Scanner will determine gas compositions in the survey area over the caldera. In addition, if it is deemed safe to do so, a shore team will collect ash and rock samples from one of the remaining islands. This work will benefit the scientific community, hazards specialists, the Kingdom of Tonga, and the general public. A short (~5 min.) video explaining the operations and scientific activities on the expedition will be produced and disseminated to the public on YouTube.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.