An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years.
10-658: The Clarence Fault is an active dextral (right lateral) strike-slip fault in the northeastern part of South Island , New Zealand . It forms part of the Marlborough fault system , which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian plate and Pacific plate , from the transform Alpine Fault to the Hikurangi Trough subduction zone . The Clarence Fault extends from about 5 km south of Haupiri , close to
20-704: A geologic hazard – one related to earthquakes as a cause. Effects of movement on an active fault include strong ground motion , surface faulting, tectonic deformation , landslides and rockfalls , liquefaction , tsunamis , and seiches . Quaternary faults are those active faults that have been recognized at the surface and which have evidence of movement during the Quaternary Period. Related geological disciplines for active-fault studies include geomorphology , seismology , reflection seismology , plate tectonics , geodetics and remote sensing , risk analysis , and others. Active faults tend to occur in
30-553: Is employed with other factors to determine the potential earthquake hazard. The geologic conditions and plate tectonic setting in much of the Western U.S. has resulted in the region being underlain by relatively thin crust and having high heat flow, both of which can favor relatively high deformation rates and active faulting. In contrast, in the Central and Eastern U.S. (CEUS) the crust is thicker, colder, older, and more stable. Furthermore,
40-581: The Alpine Fault to about 10 km west of Ward . This fault is the only member of the Marlborough Fault System to have neither a clear junction with the Alpine fault to the southwest nor a northeastward continuation to the coast. The southwestern part of the fault consists of many fault traces and has a transpressive "pop-up" geometry. To the northeast the strands merge to form a single fault trace in
50-593: The CEUS is thousands of miles from active plate boundaries, so the rates of deformation are low in this region. Nevertheless, the CEUS has had some rather large earthquakes in historical times, including a series of major earthquakes near New Madrid, Missouri in 1811–1812 , a large earthquake near Charleston, South Carolina in 1886, and the Cape Ann earthquake northeast of Boston in 1755. 1811%E2%80%9312 New Madrid earthquakes Too Many Requests If you report this error to
60-467: The Late Pleistocene, about 18,000 years ago. This gives an average slip rate of 3.6–4.4 mm/yr with an average slip of about 5 m for each event. In the northeastern part of the fault, the estimated slip-rate is somewhat higher, 4.7 mm/yr and the average slip also higher at about 7 m. A recurrence interval of about 1500 years has also been estimated for this part of the fault. The timing of
70-471: The middle of the Waiau Toa / Clarence River valley, from which the fault gets its name. At the surface the displacement on this continuous trace appears to be nearly pure horizontal, but continuous uplift of the neighbouring Inland Kaikōura Range over the same period, suggests that some of the dip-slip component thought to be present at depth on the fault zone is transferred onto thrust or reverse faults under
80-461: The most recent earthquake on the northeastern fault segment is poorly constrained, but is likely to be in the range 950–2000 years ago. The likelihood of a significant earthquake happening on the Clarence Fault in the next 50–100 years is regarded as moderate to possibly high, although poorly constrained by the available data. Active fault Active faulting is considered to be
90-488: The range. An extra 10° of clockwise rotation has been recognised within the block that lies northeast of the tip of the Clarence fault. The Elliott Fault branches from the central portion of the Clarence Fault and then rejoins it. A recurrence interval for earthquakes along this fault is estimated to be 2000–3500 years. Measurements from the southwestern part of the fault suggest 76–80 m of dextral displacement since
100-591: The vicinity of tectonic plate boundaries, and active fault research has focused on these regions. Active faults tend to occur less within the area of any given plate. The fact that intraplate regions may also present seismic hazards has only recently been recognized. Various geologic methods are used to define the boundaries of an active fault such as remote sensing and magnetic measurements, as well as other ways. Several types of data, such as seismologic reports or records over time, are used to gauge fault activity. Activity and fault area are correlated, and risk analysis
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