Mw7.2 Nippes, Haiti Earthquake: Sentinel-1 and ALOS-2 Interferometry H. Zoe Yin1, Xioahua Xu2, Jennifer S. Haase1, Roby Douilly3, David T. Sandwell1, Bernard Mercier de Lépinay4 1Institute for Geophysics and Planetary Physics, University of California, San Diego, CA, USA 2University of Texas Institute for Geophysics, Austin, TX, USA 3University of California, Riverside, CA, USA 4 CNRS Université Côte d'Azur, Valbonne, France The Mw7.2 Nippes, Haiti earthquake struck on August 14, 2021 (8:29 am local time) on Haiti's southwest peninsula. The earthquake occurred 125 km west of Port-au-Prince at a depth of 10 km with an oblique thrust faulting mechanism. The earthquake occurred along the Enriquillo-Plantain Garden fault (EPGF) zone, about 100 km west of the Mw7.0 2010 Haiti earthquake. Two InSAR satellites were operational before the earthquake and continue to collect measurements of line-of-sight (LOS) deformation. The C-band Sentinel-1 satellites, operated by the European Space Agency (ESA), provide a 6-day coverage (ascending and descending tracks) of the earthquake sequence. These data are available on the Sentinel Data Hub. The L-band ALOS-2 satellite, operated by the Japanese Aerospace Exploration Agency (JAXA), collected ascending ScanSAR data can be found on the ALOS-2 User Interface Gateway. This page is to provide line-of-sight deformation data from Sentinel-1 and ALOS-2 surrounding the 2021 earthquake. The InSAR data are processed with open source software GMTSAR and mapped using Generic Mapping Tools (GMT). The InSAR phase are filtered with a 300 m Gaussian filter and the line-of-sight data are acquired by merging different swaths' phase and then unwrapped using snaphu. We also include KMZ files for visualization in Google Earth with some interpretations. A manuscript published in Bulletin of the Seismological Society of America based this data is available here: https://doi.org/10.1785/0120220109 Background The earthquake ruptured ~80 km from Nippes towards the west, in two main slip patches with primarily dip-slip in the east and strike slip in the west (USGS). The EPGF is part of the system of strike slip and thrust faults which constitute the northeast boundary of the Caribbean tectonic plate. The plate boundary motion transitions from pure strike slip south of Cuba to subduction in the Antilles. The slip rate along the EPGF fault zone determined from GPS data is 10-11.4 mm/yr of oblique motion (Symithe et al., 2016). The rupture leaves a ~60 km segment of the EPGF unruptured between this and the 2010 Haiti M7.0 earthquake rupture on the Leogane fault (Symithe et al, 2015). Given the time since the historic earthquakes in 1701, 1751 and 1770 on this plate boundary (Manaker et al., 2008), there remains accumulated strain on the unruptured Mirogoane segment to the east of the August 14 event. Overview of the southern peninsula of Haiti, highlighting the epicenters of the 2021 M7.2 and 2010 M7.0 earthquakes and major historic earthquakes (stars). Aftershocks from 2010 on the Léogane – Trois Baies fault are from Douilly et al. (2013). Aftershocks from 2021 are from the Ayiti-Séismes network. Mapped EPGFZ faults (solid lines) are from Saint Fleur et al. (2020). Data We compile Sentinel-1 and ALOS-2 repeat acquisitions surrounding the time of the 2021 earthquake and use GMTSAR software to process the raw data. Interferograms are Gaussian filtered at 200 m and re-sampled at 50 m before further processing. We unwrap the phase using the Statistical-Cost, Network-Flow Algorithm for Phase Unwrapping (SNAPHU), with nearest neighbor interpolation over the low coherence areas and water surfaces. The resulting LOS plots below show surface deformation in the line-of-sight of the observing satellite, where positive indicates that the ground pixel has moved towards the satellite. Timeline of all SAR scene acquisitions used in this work with the vertical red dashed line marking the Aug 14 earthquake. Sentinel-1 acquisitions are frequent, with ascending and descending acquisitions less than two weeks before the 2021 earthquake. In contrast, ALOS-2 acquisitions are infrequent with the closest usable ALOS-2 acquisitions prior to the earthquake are more than 6 months before the earthquake. Note the breaks in the horizontal axis in grey which represent large time periods between ALOS-2 acquisitions. All InSAR scene outlines, note the addition of the ALOS-1 scene which was acquired following the 2010 earthquake. Google Earth Project Download Download a Google Earth project file containing all InSAR pairs included below as layers. Also includes features picked from these pairs and other published resources to contextualize the InSAR data. Most recent Google Earth project KMZ files Line of Sight (LOS) vectors for modeling LOS data are available for download below. They are provided as csv files, are downsampled to 500m, and have the following columns:  lon, lat, elevation (m), look vector (E),  look vector (N),  look vector (U), los (mm) *Note: look vectors point from the specified point on the ground towards the observing satellite. *Note: earthquake-spanning Sentinel pairs may not capture the full extent of coseismic deformation but are included for completeness. For more information, see  https://doi.org/10.1785/0120220109 File names are in the format: <SAT>_<PATH>_<DATE1>-<DATE2>_<DATATYPE>_<DTR>.<EXT> SAT = Satellite (ALOS-2 is A2, Sentinel is S1) PATH = A or D indicates ascending or descending pass, followed by the track/path number.  DATE1 = Primary scene acquisition in the format YYYYMMDD DATE2 = Reference scene acquisition in the format YYYYMMDD DATATYPE = LOS in this case DTR = will include “_dtr” if the dataset has been detrended by removing a simple ramp. EXT = LOS data files are in .csv format Click here to download all CSV files Available files include: A2_A042_20210101-20210827_los.csv A2_A042_20210101-20210827_los_dtr.csv A2_A042_20210827-20211231_los.csv A2_A042_20210827-20211231_los_dtr.csv A2_A043_20201223-20210818_los.csv A2_A043_20210818-20210901_los.csv A2_D138_2019-12-10_2021-08-17_los.csv A2_D138_20191210-20210817_los.csv A2_D138_20191210-20210817_los_dtr.csv A2_D144_20210819_20210902_los.csv S1_A004_20210805-20210817_p06_80_los.csv S1_A004_20210817-20210823_los.csv S1_A004_20210823-20210829_dtr_los.csv S1_D142_20210803-20210815_los.csv S1_D142_20210803-20210815_los_dtr.csv S1_D142_20210821-20210827_los.csv S1_D142_20210821-20210827_los_dtr.csv ALOS-2 Ascending Track 042 (Stripmap): Pair 2021/01/01 - 2021/08/27    Co & postseismic & secondary fault structures PHASE: phasefilt_ll.grd PHASE GRADIENT: yphase_mask_ll.grd LINE OF SIGHT: los_ll.grd ALOS-2 Ascending Track 042 (Stripmap): Pair 2021/08/27 - 2021/12/31    Postsesismic & secondary fault structures PHASE: phasefilt_ll.grd PHASE GRADIENT: yphase_mask_ll.grd LINE OF SIGHT: los_ll_dtr.grd ALOS-2 Ascending Track 042 (Stripmap): Pair 2021/01/01 - 2021/12/31 All Co & postseismic (Jan 1 - Dec 31) PHASE: phasefilt_ll.grd PHASE GRADIENT: yphase_mask_ll.grd LINE OF SIGHT: los_ll.grd ALOS-2 Ascending Track 042 (Stripmap): Phase gradient stack The gradient of the phase taken in the azimuth (flight) direction and stacked using all ALOS-2 ascending track pairs between Dec 23, 2020 and Dec 31, 2021 (3 pairs for A042 and 5 pairs for A043) PHASE GRADIENT STACK:  yphase_mask_ll_stack.grd ALOS-2 Ascending Track 043 (Stripmap): 2020/12/23 - 2021/08/18 Coseismic & surface rupture PHASE: phasefilt_ll.grd  PHASE GRADIENT:  yphase_mask_ll_2020-12-23_2021-08-18.grd LINE OF SIGHT: los_ll.grd ALOS-2 Ascending Track 043 (Stripmap): Phase gradient stack The gradient of the phase taken in the azimuth (flight) direction and stacked using all ALOS-2 ascending track pairs between Dec 23, 2020 and Dec 31, 2021 (3 pairs for A042 and 5 pairs for A043) PHASE GRADIENT STACK:  yphase_mask_ll_stack.grd ALOS-2 Descending Track 138 (ScanSAR): 2019/12/10 - 2021/08/17 Coseismic Deformation. PHASE: phasefilt_ll.grd                        PHASE GRADIENT: N/A                                 LINE OF SIGHT: los_ll_dtr.grd ALOS-1 Ascending Track 138 (FBD): 2010/01/16 - 2010/06/23 2010 Postseismic Deformation PHASE: phasefilt_ll.grd PHASE GRADIENT: yphase_mask_ll.grd                                                                                      Sentinel-1 Descending track D142: 2021/08/03 - 2021/08/15 Descending coseismic interferogram PHASE: phasefilt_ll.grd Sentinel-1 Descending track D142: 2021/08/15 - 2021/08/21 Post-seismic Interferogram PHASE: phasefilt_ll.grd   Sentinel-1 Descending track D142: 2021/08/21 - 2021/08/27 Post-seismic Interferogram PHASE: phasefilt_ll.grd Sentinel-1 Ascending track A004: 2021/08/05 - 2021/08/17 Ascending coseismic interferogram PHASE: phasefilt_ll.grd   Sentinel-1 Ascending track A004: 2021/08/17 - 2021/08/23 Post-seismic Interferogram PHASE: phasefilt_ll.grd Sentinel-1 Ascending track A004: 2021/08/23 - 2021/08/29 Post-seismic Interferogram PHASE: phasefilt_ll.grd Acknowledgements: Rapid InSAR data processing was supported by a National Science Foundation RAPID grant (Grant #2150704). We thank the operators of the Ayiti-Séismes earthquake monitoring network at Bureau des Mines, Faculté des Sciences, Laboratoire URGéo, Université d'état d'Haïti, Ecole Normale Supérieur, and Laboratoire Géoazur for making aftershock locations free and openly available. We thank Sylvert Paul and Francoise Courboulex at GéoAzur, Eric Calais at ENS, and Jeremy Maurer at Missouri University of Science and Technology for helpful discussions related to the earthquake. We thank ESA for the rapid acquisition and distribution of Sentinel-1 data. We thank JAXA for access to ALOS-1 and ALOS-2 data. The development of the GMTSAR software, and specifically the processing chain for Sentinel-1 and ALOS-2, was supported by the National Aeronautics and Space Administration (NASA) and the National Science Foundation through the NASA Earth Surface and Interior program (NNX16AK93G and 80NSSC19K1043), the NSF Office of Advanced Cyberinfrastructure program (OAC-1834807), and the NSF EarthScope program (EAR-1147435, EAR-1424374, EAR-1614875).