Mid-crustal detachment and ramp faulting in the Markham Valley, Papua New Guinea

Abstract

Research Article| September 01, 1998 Mid-crustal detachment and ramp faulting in the Markham Valley, Papua New Guinea C. Stevens; C. Stevens 1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 Search for other works by this author on: GSW Google Scholar R. McCaffrey; R. McCaffrey 1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 Search for other works by this author on: GSW Google Scholar E. A. Silver; E. A. Silver 2Earth Sciences Department, University of California, Santa Cruz, California 95060 Search for other works by this author on: GSW Google Scholar Z. Sombo; Z. Sombo 3Department of Surveying and Land Studies, University of Technology, Lae, Papua New Guinea Search for other works by this author on: GSW Google Scholar P. English; P. English 4National Mapping Bureau, Boroko, Papua New Guinea Search for other works by this author on: GSW Google Scholar J. van der Kevie J. van der Kevie 4National Mapping Bureau, Boroko, Papua New Guinea Search for other works by this author on: GSW Google Scholar Author and Article Information C. Stevens 1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 R. McCaffrey 1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 E. A. Silver 2Earth Sciences Department, University of California, Santa Cruz, California 95060 Z. Sombo 3Department of Surveying and Land Studies, University of Technology, Lae, Papua New Guinea P. English 4National Mapping Bureau, Boroko, Papua New Guinea J. van der Kevie 4National Mapping Bureau, Boroko, Papua New Guinea Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (9): 847–850. https://doi.org/10.1130/0091-7613(1998)026<0847:MCDARF>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 Email Permissions Search Site Citation C. Stevens, R. McCaffrey, E. A. Silver, Z. Sombo, P. English, J. van der Kevie; Mid-crustal detachment and ramp faulting in the Markham Valley, Papua New Guinea. Geology 1998;; 26 (9): 847–850. doi: https://doi.org/10.1130/0091-7613(1998)026<0847:MCDARF>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 Earthquakes and geodetic evidence reveal the presence of a low-angle, mid-crustal detachment fault beneath the Finisterre Range that connects to a steep ramp surfacing near the Ramu-Markham Valley of Papua New Guinea. Waveforms of three large (Mw 6.3 to 6.9) thrust earthquakes that occurred in October 1993 beneath the Finisterre Range 10 to 30 km north of the valley reveal 15° north-dipping thrusts at about 20 km depth. Global Positioning System measurements show up to 20 cm of coseismic slip occurred across the valley, requiring that the active fault extend to within a few hundred meters of the Earth's surface beneath the Markham Valley. Together, these data imply that a gently north-dipping thrust fault in the middle or lower crust beneath the Finisterre Range steepens and shallows southward, forming a ramp fault beneath the north side of the Markham Valley. Waveforms indicate that both the ramp and detachment fault were active during at least one of the earthquakes. While the seismic potential of mid-crustal detachments elsewhere is debated, in Papua New Guinea the detachment fault shows the capability of producing large earthquakes. 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.