Topic
Shutter ridge
About: Shutter ridge is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 224 citations.
Papers
TL;DR: In this article, two paleoseismic trenches were opened adjacent to Greenburn Stream near Kaikoura for the 2001 ILP Paleoseismology Conference, and they were excavated into deposits ponded against an uphill-facing shutter ridge.
Abstract: The Conway Segment of the dextral-slip Hope Fault is one of the fastest slipping fault segments along New Zealand s
plate boundary, but has not ruptured co-seismically in the historic period and little paleoseismic data exist to constrain its
large earthquake record. Two paleoseismic trenches were opened adjacent to Greenburn Stream near Kaikoura for the
2001 ILP Paleoseismology Conference. Both trenches were excavated into deposits ponded against an uphill-facing shutter
scarp. Trench 1, dug through a cobbly soil and surface deposit was dominated by a thick fan/fluvial sequence that was
radiocarbon dated at 4409 ± 60 C14 years BP (4844-5288 cal years BP) at the base of the trench. This trench exhibited
evidence of complex deformation from many paleoseismic events. The most recent earthquakes are difficult to constrain
due to a lack of cover stratigraphy on the fan deposits. However, the modern soil appears to be faulted and is covered by
cobbles with a weathering rind-derived age of 220 ± 60 years. Trench 2, dug ?? 50 m to the west has an expanded sequence
of the younger cover deposits. Paleoseismic event horizons have been recognised from the combined evidence of upwardterminating
faults, offset and mismatched units, a sandblow deposit, and abrupt landscape change shown by the burial of
paleosol surfaces that form the event horizons. Two paleosols underlying the modern soil are clearly faulted by two separate
rupture events. A dome of sand interpreted as a liquefaction sandblow deposit overlies the lower paleosol (event
horizon). Both paleosols are overlain by metre-thick debris deposits, interpreted as earthquake-induced rock avalanches
that cascaded off the hillslope following Mw 7 + events. Four radiocarbon dates place some constraints on the timing of
the three recent surface-rupturing events. The youngest and lowest date is 548 ± 60 C14 years BP (504-656 cal years BP)
and occurs below the lower paleosol. It constrains the maximum duration of time in which the last 2 earthquake events
occurred to be 545 years (1295-1840 A.D.). This is consistent with the average Recurrence Interval (RI) of 180-310 years
that we determine using two independent paths. The soil record indicates that each event is separated by a significant period
of time, comparable to the calculated RI. The most recent event is constrained between ca. 1780 A.D. ± 60 years, taking
into account the dates from these trenches, a weathering rind age, and from stratigraphic correlation at the site. Event
III probably occurred before 1220 A.D. A maximum dextral slip rate of 23 ± 4 mm/yr is calculated from the minimum
fan age and the offset/deflection of a stream channel along the shutter ridge. In concert with the estimate of single event
displacement (5-6 m), these results show that the Conway Segment of the Hope Fault is fast-slipping and has ruptured
regularly as a result of large earthquakes prior to the European colonisation of New Zealand.
78 citations
TL;DR: In this article, a new trench study has been performed, 60 km to the northeast of Merida in the central Venezuelan Andes, where the fault forms a releasing bend, comprising two conspicuous late Holocene fault strands that are about 1 km apart, and they carry about 70% and 30% of the 7-10 mm/yr net slip rate measured in this sector, which is based on a 40 vs. 85-100 m right-lateral offset of the Late Pleistocene Los Zerpa moraines.
71 citations
TL;DR: In this article, the authors evaluate the possibility of non-steady slip over millennial timescales using displaced Late Holocene alluvium along the central Garlock fault in Pilot Knob Valley.
Abstract: Average geologic slip rates along the central Garlock fault, in eastern California, are thought to have been relatively steady at 5–7 mm/yr since at least the Late Pleistocene, yet present-day rates inferred from geodetic velocity fields are indistinguishable from zero. We evaluate the possibility of non-steady slip over millennial timescales using displaced Late Holocene alluvium along the central Garlock fault in Pilot Knob Valley. Truncation of a Late Holocene alluvial fan deposit against a shutter ridge requires a minimum of 30–37 m of displacement since deposition of the fan; maximum allowable displacement is 43–50 m. The extent of soil development atop the fan surface and optically stimulated luminescence ages bracket fan deposition between 3.5 and 4.5 ka. Together, these data require that slip rates during the Late Holocene were ∼7–14 mm/yr, with a preferred rate of ∼11–13 mm/yr. Our results, in conjunction with previous estimates of displacement over the past ∼15 ka, require significant temporal variations in strain release along the Garlock fault and confirm previous suggestions that interactions among fault systems in eastern California give rise to alternating periods of fault activity and quiescence.
34 citations
18 citations
TL;DR: A paleoseismic investigation across the Santa Cruz Mountains section of the San Andreas fault at Mill Canyon indicates that four surface-rupturing earthquakes have occurred there during the past ∼500 years as mentioned in this paper.
Abstract: A paleoseismic investigation across the Santa Cruz Mountains section of the San Andreas fault at Mill Canyon indicates that four surface‐rupturing earthquakes have occurred there during the past ∼500 years. At this site, right‐lateral fault slip has moved a low shutter ridge across the mouth of the canyon, ponding latest Holocene sediments. These alluvial deposits are deformed along a narrow zone of faulting. There is excellent evidence for a 1906 ( M 7.8) and three earlier earthquakes consisting of well‐developed fissures, scarps, and colluvial wedges. Deformation resulting from the earlier earthquakes is comparable to that from 1906, suggesting they also were large‐magnitude events. The earthquake prior to 1906 occurred either about A.D. 1750 (1711–1770) or A.D. 1855 (1789–1904), depending on assumptions incorporated into two alternative OxCal models. If the later age range is correct, then the earthquake may have been a historical early‐to‐mid‐nineteenth‐century earthquake, possibly the A.D. 1838 earthquake. Both models are viable, and there is no way to select one over the other with the available data. Two earlier earthquakes occurred about A.D. 1690 (1660–1720) and A.D. 1522 (1454–1605). Using OxCal, recalculation of the age of the reported penultimate earthquake reported from the Grizzly Flat site, located about 10 km northwest of Mill Canyon, indicates it occurred about A.D. 1105–1545, earlier than any of the past three earthquakes, and possibly correlates to the fourth earthquake at Mill Canyon.
8 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2018 | 1 |
| 2014 | 1 |
| 2012 | 1 |
| 2009 | 1 |
| 1999 | 1 |