On July 4-5, 2019, the M6.4 and M7.1 Searles Valley and Ridgecrest earthquake sequence ruptured a geometrically complex 50 km long system of faults within the Eastern California Shear Zone (ECSZ), just north of the Garlock fault. These conjugate events resulted in several meters of strike-slip and dip-slip along a fairly complex rupture, extending from the surface down to 15 km. Coseismic geodetic observations reveal 500+ mm of horizontal surface slip and at least 35 mm of vertical uplift at near-field station P595, located 10 km from the rupture zone. Some 70+ km away, smaller but still measurable subsidence and uplift motions (~8-12 mm) were also recorded, as predicted by far-field elastic dislocation theory. Similarly, over the next several months to years, vertical velocity transients are anticipated, characteristic of postseismic viscoelastic relaxation of the lower crust and upper mantle.
A co-seismic slip source inversion of both events using GNSS and InSAR (Sentinel-1/ALOS-2) line-of-sight deformation data was computed (Xu et al., 2019). The modeled vertical coseismic deformation field of the Ridgecrest earthquake sequence reveals alternating quadrants of deformation (+/- 35 mm) that straddle the rupture and span a wide (~200 km) region of the ECSZ. (Ward et al., 2022)
Website:
https://topex.ucsd.edu/SV_7.1
Above: (Top) Near-real time line-of-sight deformation data from both the Mw6.4 (July 4, 2019) and the Mw7.1(July 5, 2019) Ridgecrest earthquakes. Both wrapped interferograms and line-of-sight (LOS) displacement maps were processed with open-source software GMTSAR. (Bottom) Vertical coseismic GNSS measured displacements and modeled vertical displacement field resulting from 3-D surface displacement model of slip source inversion.
Related Publications:
Ward, L., Guns, K., B. Smith-Konter, X. Xu, Y. Bock, and D.T. Sandwell (2022), Vertical postseismic deformation of the 2019 Ridgecrest Earthquake sequence, Journal of Geophysical Research, 2021JB023331.
Xu, X., D.T. Sandwell, L. Ward, C. Milliner, B. Smith-Konter, P. Feng, and Y. Bock (2020), Surface deformation associated with fractures near the 2019 Ridgecrest earthquake sequence, Science, 370, https://doi:10.1126/science.abd1690.
Ponti, D., J. L. Blair, C. M. Rosa, K. Thomas, A. J. Pickering, S. Akciz, S. Angster, J. P. Avouac, J. Bachhuber, S. Bacon, S. Bennett, K. Blake, S. Bork, B. Brooks, T. Bullard, P. Burgess, C. Chupik, T. Dawson, M. DeFrisco, J. Delano, S. DeLeong, J. Dolan, A. Donnellan, C. DuRoss, T. Ericksen, E. Frost, G. Funning, R. Gold, N. Graehl, C. Gutierrez, E. Haddon, A. Hatem, J. Helms, J. Hernandez, C. Hitchcock, P. Holland, K. Hudnut, K. Kendrick, R. Koehler, O. Kozaci T. Ladinsky, R. Leeper, C. Madugo, M. Mareschal, J. McDonald, D. McPhillips, C. Milliner, D. Mongovin, A. Morelan, J. Nevitt, M. OʻNeal, B. Olson, M. Oskin, S. Padilla, J. Patton, B. Philibosian, I. Pierce, C. Pridmore, N. Roth, D. Sandwell, K. Scharer, G.Seitz, D. Singleton, B. Smith-Konter, E. Spangler, B. Swanson, J. Thompson Job, J. Treiman, F. Turner, A. Williams, X. Xu, J. Zachariasen, J. Zimmerman, R. Zinke (2020), Documentation of surface fault rupture and ground‐deformation features produced by the 4 and 5 July 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence, (2019), Seismological Research Letters, https://doi.org/10.1785/0220190322.
Dawson, T., C. DuRoss, R. Gold, K. Scharer, D. Ponti, T. Ladinsky, V.E. Langenheim, D. McPhillips, A. Morelan, C. Milliner, K. Kendrick, J. Hernandez, K. Hudnut, S. Akciz, S. Angster, J.P. Avouac, S. Bacon, J. Bachhuber, N. Barth, S. Bennett, L. Blair, K. Blake, S. Bork, B. Brooks, T. Bullard, W.P. Burgess, C. Chupik, M. DeFrisco, J. Delano, J. Dolan, A. Donnellan, T. Ericksen, E. Frost, G. Funning, N. Graehl, C. Guttierez, E. Haddon, P. Holland, A. Hatem, J. Helms, C. Hitchcock, J. Thompson Jobe, R. Koehler, O. Kozaci, C. Madugo, R. Leeper, M. Mareschal, D. McPhillips, M. O’Neil, J. Nevitt, B. Olson, S. Padilla, J. Patton, B. Philibosian, A. J. Pickering, I. Pierce, C. Pridmore, N. Roth, D. Sandwell, G. Seitz1, D. Singleton, B. Smith-Konter, E. Spangler, B. Swanson, K. Thomas, J. Treiman, F. Valencia, A. Williams, X. Xu, J. Zachariasen, J. Zimmerman, and R. Zinke (2020), Field-based observations of surface ruptures associated with the 2019 Ridgecrest earthquake sequence, Bulletin of the Seismological Society of America.
Xu, X., D.T. Sandwell, and B. Smith-Konter (2019), Co-seismic displacements and surface fractures from Sentinel-1 InSAR: 2019 Ridgecrest Earthquakes, Seismol. Res. Lett., https://doi.org/10.1785/0220190275.
