Possible seismogenic shallow-dipping normal faults in the Woodlark-D'Entrecasteaux extensional province, Papua New Guinea

Abstract

Research Article| December 01, 1991 Possible seismogenic shallow-dipping normal faults in the Woodlark-D'Entrecasteaux extensional province, Papua New Guinea Geoffrey A. Abers Geoffrey A. Abers 1Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar Geology (1991) 19 (12): 1205–1208. https://doi.org/10.1130/0091-7613(1991)019<1205:PSSDNF>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Geoffrey A. Abers; Possible seismogenic shallow-dipping normal faults in the Woodlark-D'Entrecasteaux extensional province, Papua New Guinea. Geology 1991;; 19 (12): 1205–1208. doi: https://doi.org/10.1130/0091-7613(1991)019<1205:PSSDNF>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Active normal faults dipping less than 30° have not been documented in the seismic record, but they are commonly observed in geologic structures. One interpretation is that seismogenic low-angle faulting is physically impossible and that the geologic structures do not form at shallow dips. To better examine this problem, teleseismic body waves were inverted to determine source parameters for five large earthquakes in the Woodlark-D'Entrecasteaux region, a rare example of active continental extension associated with Pliocene-Quaternary metamorphic core complexes. The inversions show that at least two and possibly four events are consistent with normal dip slip on shallow-dipping faults. The largest earthquake (Mw = 6.8) is located near the mapped core complexes. The shallow-dipping plane for this event, determined to dip between 10° and 25°, is nearly coplanar to the faults bounding the core complexes and may represent slip on these or other parallel low-angle structures. Although slip on the conjugate high-angle plane cannot be ruled out, observations of Quaternary uplift and the similarity to the adjacent core-complex-bounding structures favor motion on the low-angle plane. Similar earthquake mechanisms have not yet been documented in most other extensional provinces, perhaps because instances of active core-complex exhumation are rare. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.