Paleoseismology of an active reverse fault in a forearc setting: The Poukawa fault zone, Hikurangi forearc, New Zealand

Research Article| September 01, 1998 Paleoseismology of an active reverse fault in a forearc setting: The Poukawa fault zone, Hikurangi forearc, New Zealand Harvey M. Kelsey; Harvey M. Kelsey 1Department of Geology, Humboldt State University, Arcata, California 95521 Search for other works by this author on: GSW Google Scholar Alan G. Hull; Alan G. Hull 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Search for other works by this author on: GSW Google Scholar Susan M. Cashman; Susan M. Cashman 1Department of Geology, Humboldt State University, Arcata, California 95521 Search for other works by this author on: GSW Google Scholar Kelvin R. Berryman; Kelvin R. Berryman 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Search for other works by this author on: GSW Google Scholar Patricia H. Cashman; Patricia H. Cashman 3Department of Geological Sciences, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar James H. Trexler, Jr.; James H. Trexler, Jr. 3Department of Geological Sciences, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar John G. Begg John G. Begg 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Search for other works by this author on: GSW Google Scholar Author and Article Information Harvey M. Kelsey 1Department of Geology, Humboldt State University, Arcata, California 95521 Alan G. Hull 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Susan M. Cashman 1Department of Geology, Humboldt State University, Arcata, California 95521 Kelvin R. Berryman 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Patricia H. Cashman 3Department of Geological Sciences, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 James H. Trexler, Jr. 3Department of Geological Sciences, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 John G. Begg 2Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (9): 1123–1148. https://doi.org/10.1130/0016-7606(1998)110<1123:POAARF>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Harvey M. Kelsey, Alan G. Hull, Susan M. Cashman, Kelvin R. Berryman, Patricia H. Cashman, James H. Trexler, John G. Begg; Paleoseismology of an active reverse fault in a forearc setting: The Poukawa fault zone, Hikurangi forearc, New Zealand. GSA Bulletin 1998;; 110 (9): 1123–1148. doi: https://doi.org/10.1130/0016-7606(1998)110<1123:POAARF>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 SocietyGSA Bulletin Search Advanced Search Abstract The Poukawa fault zone, on the North Island of New Zealand within the forearc of the Hikurangi subduction zone, consists of a series of en echelon reverse faults and companion hanging-wall anticlines. The geomorphically expressed length of the fault zone is 34 km. However, on the basis of coseismic deformation associated with an Ms 7.8 earthquake in 1931 and the presence of blind faults north of the geomorphically expressed fault zone, it appears that the seismogenic length of the fault zone may be as much as 130 km. On the basis of chronostratigraphic horizons identified in each of three trenches evenly distributed along the exposed fault zone, from which a paleoseismological record for the past ∼25 k.y. can be determined, there is not a characteristic rupture length for earthquakes. Some slip events are confined to the ∼10–20-km-long southern part of the fault zone, whereas other slip events may have ruptured the entire 34 km length of the geomorphically expressed fault zone. At least two slip events that occurred in the northern part of the fault zone did not occur in the southern part of the zone. The largest earthquake recorded in the trenches had a maximum reverse slip in excess of 10 m. We infer that this prehistoric earthquake, similar to the 1931 earthquake, entailed slip on faults along the geomorphically expressed fault zone and on blind faults to the north. This prehistoric earthquake may have had a rupture length (surface plus subsurface) in excess of 100 km.Average earthquake repeat times on the fault zone range from 3–7.5 k.y. for the southern and middle part of the zone to 7–12 k.y. for the northern part of the fault zone. Average single-event slip ranges from 3 m to as much as 6 m. Slip was initially accommodated at the surface primarily by folding. With successive slip events, however, coseismic displacements propagated to the surface and surface deformation became increasingly dominated by reverse slip on fault planes.The Poukawa fault zone is part of a foreland-propagating fold and thrust belt in the forearc of the Hikurangi subduction zone. Older, actively eroding hanging-wall anticlines are present to the west of the fault zone toward the volcanic arc, whereas younger folds are developing above blind reverse faults east of the main fault trace. In addition to propagating to the east, the fault zone is propagating northward beneath the Heretaunga Plains. This active propagation testifies to ongoing and evolving contractional forearc deformation in response to oblique plate convergence. 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.