2017 Valparaíso earthquake sequence and the megathrust patchwork of central Chile. Issue 17 (14th September 2017)

• Record Type: Journal Article
• Authors: Nealy, Jennifer L.; Herman, Matthew W.; Moore, Ginevra L.; Hayes, Gavin P.; Benz, Harley M.; Bergman, Eric A.; Barrientos, Sergio E.
• Is Part Of: Geophysical research letters. Volume 44:Issue 17(2017)
• Page Start: 8865
• Page End: 8872
• Publication Date: 2017-09-14
• Subjects: Valparaíso earthquake -- subduction zones -- finite fault models -- moment accumulation -- relocation -- coulomb stress; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL074767
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: In April 2017, a sequence of earthquakes offshore Valparaíso, Chile, raised concerns of a potential megathrust earthquake in the near future. The largest event in the 2017 sequence was a M 6.9 on 24 April, seemingly colocated with the last great‐sized earthquake in the region—a M 8.0 in March 1985. The history of large earthquakes in this region shows significant variation in rupture size and extent, typically highlighted by a juxtaposition of large ruptures interspersed with smaller magnitude sequences. We show that the 2017 sequence ruptured an area between the two main slip patches during the 1985 earthquake, rerupturing a patch that had previously slipped during the October 1973 M 6.5 earthquake sequence. A significant gap in historic ruptures exists directly to the south of the 2017 sequence, with large enough moment deficit to host a great‐sized earthquake in the near future, if it is locked. Key Points: The 2017 Valparaíso sequence occurred between the two main patches of moment release from the 1985 Valparaíso earthquake A large gap in historic ruptures south of the 2017 sequence, suggests a potential for great‐sized earthquakes here in the near future Low resolution in geodetic coupling to the south of the 2017 sequence denotes the need for seafloor geodetic monitoring in subduction zones