Figure showing model reconstructions of the Palu tsunami
Figure shows model reconstructions of the Palu tsunami. Map shows tsunami video locations (white circles), coastline retreat identified from satellite imagery (triangles), and flight path and timing (in seconds after the mainshock) of the aircraft pilot who recorded the point-source tsunami. Panels to the left and right show a comparison of measured runup (Fritz, 2018) with those simulated from available rupture models (Socquet et al., 2019; USGS 2018). The lower panel shows tsunami waveforms reconstructed from video footage (red) versus those predicted by the Socquet et al., (2019) (blue) and USGS (2018) (tan) rupture models. The green line at Pantoloan represents the tide gauge record at that location; note its lower temporal sampling with respect to the video-inferred reconstruction. Dashed red lines represent waveform segments interpreted with lower confidence. Credit: Carvajal et al. [2019], Figure 2
Source: Geophysical Research Letters

A devastating tsunami occurred in Palu Bay on Sulawesi, Indonesia, following the 2018 Palu earthquake. This tsunami was unusually large according to conventional wisdom, because it was generated by a strike slip event. Carvajal et al. [2019] present a fascinating new approach to construct modeled tsunami waveforms using social media video footage shared by people who experienced the tsunami and recording from local CCTV cameras. These videos were analyzed to quantify the timing, amplitude, and period of the tsunami at different locations around Palu Bay.

Results show that either current rupture models of the earthquake underestimate the seafloor displacement it caused, or that non-tectonic sources were involved in generating the tsunami. This analysis also reveals significant short period tsunami waves which were not recorded by the local tide gauge because the sampling rate at the station was too large. This demonstrates that data obtained from unconventional devices can be extremely useful to better understand tsunami phenomena.

Citation: Carvajal, M., Araya‐Cornejo, C., Sepúlveda, I., Melnick, D., & Haase, J. S. [2019]. Nearly instantaneous tsunamis following the Mw 7.5 2018 Palu earthquake. Geophysical Research Letters, 46.

—Gavin P. Hayes, Editor, Geophysical Research Letters

Text © 2019. The authors. CC BY-NC-ND 3.0
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