Citizen seismology helps decipher the 2021 Haiti earthquake

Abstract

The August 14, Mw7.2, Nippes earthquake in Haiti occurred within the same fault zone as its devastating, Mw7.0, 2010 predecessor but struck the country when field access was limited by insecurity and conventional seismometers from the national network were inoperative. A network of citizen seismometers installed in 2019 provided near-field data critical to rapidly understand the mechanism of the mainshock and monitor its aftershock sequence. Their real-time data define two aftershock clusters that coincide with two areas of coseismic slip derived from inversions of conventional seismological and geodetic data. Machine learning applied to data from the citizen seismometer closest to the mainshock allows us to forecast aftershocks as accurately as with the network-derived catalog. This shows the utility of citizen science contributing to the understanding of a major earthquake.

Rupture Geometry and Slip Distribution of the Mw 7.2 Nippes Earthquake, Haiti, From Space Geodetic Data

“…We find that the misfit is lowest for a RSF segment dipping to the north at a 86 ± 2° angle (within 5% error) and a thrust segment dipping to the north at a 66 ± 4° angle (within 5% error). The hypocenter location from Calais, Symithe, Monfret, et al (2022) matches that latter rupture segment at depth. The square-root of the variance of residuals displacements (RMSE), a measure of the model misfit, ranges between 0.01 m misfit for the Sentinel descending track, 0.09 m for the ALOS-2 SM acquisition, 0.05 m for the ALOS-2 WD acquisition, and 0.08 m for the GNSS data (Figure 4).…”

“…The 14 August, Mw 7.2 Nippes earthquake is the most recent example of this dual mode of strain release in southern Haiti. Okuwaki and Fan (2022) and Calais, Symithe, Monfret, et al (2022) used multiple geophysical data sets to show that the rupture likely initiated on a reverse thrust fault segment, then transitioned westward to a steeper, strike-slip, fault segment. Maurer et al (2022) reached a similar conclusion, though using a more complex rupture geometry, including 5 fault segments inferred from geological mapping.…”

Complex Rupture and Triggered Aseismic Creep During the 14 August 2021 Haiti Earthquake From Satellite Geodesy

“…The inclusion of multiple fault strands results in better overall fit to the data and higher moment and is required to explain the step-over in deformation that is visible in the InSAR observations (see Figure 2 and Figures S4, especially subplot (e), and S8 in Supporting Information S1). Slip on the northernmost thrust fault is uncertain but consistent with the location of aftershocks (Figure 1; Calais et al, 2022). Further work is needed utilizing seismic data to separate seismic and aseismic moment during the coseismic and early postseismic periods.…”

Atmospheric waves and global seismoacoustic observations of the January 2022 Hunga eruption, Tonga

“…Geophysical records of the January 2022 Hunga eruption represent an unparalleled global dataset of atmospheric wave generation and propagation, providing an opportunity for multi-technology observation, modeling, and validation that is unprecedented in the modern record. The datasets highlighted here are not exhaustive; there is outstanding potential for augmenting details of the global wavefield capture by incorporating numerous additional interdisciplinary datasets, including citizen-science data ( 27 , 28 ). The January 2022 Hunga eruption presents an extraordinary opportunity to advance understanding of rarely captured physical phenomena, including global Lamb wave propagation, atmospheric free-oscillations coupling with the solid Earth, nonlinear energy cascading in atmospheric wave propagation, excitation of infrasound and audible sound at global distances, air-sea waves, and many others.…”