scholarly journals Slip rate determined from cosmogenic nuclides on normal-fault facets

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 66-70
Author(s):  
Jim Tesson ◽  
Lucilla Benedetti ◽  
Vincent Godard ◽  
Catherine Novaes ◽  
Jules Fleury ◽  
...  
Keyword(s):  
Slip Rate ◽  
Normal Fault ◽  
Time Frame ◽  
Fault Slip ◽  
Normal Faults ◽  
Slip Rates ◽  
Topographic Features ◽  
The Past ◽  
Data Inversion ◽  
Fault Slip Rates

Abstract Facets are major topographic features built over several 100 k.y. above active normal faults. Their development integrates cumulative displacements over a longer time frame than many other geomorphological markers, and they are widespread in diverse extensional settings. We have determined the 36Cl cosmogenic nuclide concentration on limestone faceted spurs at four sites in the Central Apennines (Italy), representing variable facet height (100–400 m). The 36Cl concentration profiles show nearly constant values over the height of the facet, suggesting the facet slope has reached a steady-state equilibrium for 36Cl production. We model the 36Cl buildup on a facet based on a gradual exposure of the sample resulting from fault slip and denudation. Data inversion with this forward model yields accurate constraints on fault slip rates over the past 20–200 k.y., which are in agreement with the long-term rate independently determined on some of those faults over the past 1 m.y. 36Cl measurements on faceted spurs can therefore constrain fault slip rate over time spans as long as 200 k.y., a time period presently undersampled in most morphotectonic studies.

scholarly journals New geodetic constraints on southern San Andreas fault-slip rates, San Gorgonio Pass, California

Geosphere ◽  
2020 ◽  
Author(s):  
Katherine A. Guns ◽  
Richard A Bennett ◽  
Joshua C. Spinler ◽  
Sally F. McGill
Keyword(s):  
Velocity Field ◽  
Southern California ◽  
San Andreas Fault ◽  
Plate Boundary ◽  
Slip Rate ◽  
Fault Slip ◽  
Slip Rates ◽  
San Andreas ◽  
Fault Slip Rates ◽  
Gps Velocity Field

Assessing fault-slip rates in diffuse plate boundary systems such as the San Andreas fault in southern California is critical both to characterize seis­mic hazards and to understand how different fault strands work together to accommodate plate boundary motion. In places such as San Gorgonio Pass, the geometric complexity of numerous fault strands interacting in a small area adds an extra obstacle to understanding the rupture potential and behavior of each individual fault. To better understand partitioning of fault-slip rates in this region, we build a new set of elastic fault-block models that test 16 different model fault geometries for the area. These models build on previ­ous studies by incorporating updated campaign GPS measurements from the San Bernardino Mountains and Eastern Transverse Ranges into a newly calculated GPS velocity field that has been removed of long- and short-term postseismic displacements from 12 past large-magnitude earthquakes to estimate model fault-slip rates. Using this postseismic-reduced GPS velocity field produces a best- fitting model geometry that resolves the long-standing geologic-geodetic slip-rate discrepancy in the Eastern California shear zone when off-fault deformation is taken into account, yielding a summed slip rate of 7.2 ± 2.8 mm/yr. Our models indicate that two active strands of the San Andreas system in San Gorgonio Pass are needed to produce sufficiently low geodetic dextral slip rates to match geologic observations. Lastly, results suggest that postseismic deformation may have more of a role to play in affecting the loading of faults in southern California than previously thought.

scholarly journals A systems-based approach to parameterise seismic hazard in regions with little historical or instrumental seismicity: active fault and seismogenic source databases for southern Malawi

Solid Earth ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 187-217
Author(s):  
Jack N. Williams ◽  
Hassan Mdala ◽  
Åke Fagereng ◽  
Luke N. J. Wedmore ◽  
Juliet Biggs ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Slip Rate ◽  
Fault Slip ◽  
East African ◽  
Slip Rates ◽  
Fault Slip Rates ◽  
Seismogenic Source ◽  
Recurrence Intervals ◽  
African Rift

Abstract. Seismic hazard is commonly characterised using instrumental seismic records. However, these records are short relative to earthquake repeat times, and extrapolating to estimate seismic hazard can misrepresent the probable location, magnitude, and frequency of future large earthquakes. Although paleoseismology can address this challenge, this approach requires certain geomorphic setting, is resource intensive, and can carry large inherent uncertainties. Here, we outline how fault slip rates and recurrence intervals can be estimated by combining fault geometry, earthquake-scaling relationships, geodetically derived regional strain rates, and geological constraints of regional strain distribution. We apply this approach to southern Malawi, near the southern end of the East African Rift, and where, although no on-fault slip rate measurements exist, there are constraints on strain partitioning between border and intra-basin faults. This has led to the development of the South Malawi Active Fault Database (SMAFD), a geographical database of 23 active fault traces, and the South Malawi Seismogenic Source Database (SMSSD), in which we apply our systems-based approach to estimate earthquake magnitudes and recurrence intervals for the faults compiled in the SMAFD. We estimate earthquake magnitudes of MW 5.4–7.2 for individual fault sections in the SMSSD and MW 5.6–7.8 for whole-fault ruptures. However, low fault slip rates (intermediate estimates ∼ 0.05–0.8 mm/yr) imply long recurrence intervals between events: 102–105 years for border faults and 103–106 years for intra-basin faults. Sensitivity analysis indicates that the large range of these estimates can best be reduced with improved geodetic constraints in southern Malawi. The SMAFD and SMSSD provide a framework for using geological and geodetic information to characterise seismic hazard in regions with few on-fault slip rate measurements, and they could be adapted for use elsewhere in the East African Rift and globally.

scholarly journals Geomorphological reconnaissance of the Psathopyrgos and Rion-Patras Fault zones (Achaia, NW Peloponnesus).

2007 ◽  
Vol 40 (4) ◽  
pp. 1586 ◽  
Author(s):  
N. Palyvos ◽  
D. Pantosti ◽  
L. Stamatopoulos ◽  
P. M. De Martini
Keyword(s):  
Fault Zone ◽  
Fault Zones ◽  
Fault Slip ◽  
Geological Data ◽  
Slip Rates ◽  
The Holocene ◽  
Fault Slip Rates ◽  
Earthquake Ruptures ◽  
Surficial Deposits

In this communication we discuss reconnaissance geomorphological observations along the active Psathopyrgos and Rion-Patras (NE part) fault zones. These fault zones correspond to more or less complex rangefronts, the geomorphic characteristics of which provide hints on the details of the fault zone geometries, adding to the existing geological data in the bibliography. Aiming at the identification of locations suitable or potentially suitable for geomorphological and geological studies for the determination of fault slip rates in the Holocene, we describe cases of faulted Holocene landforms and associated surficial deposits. We also discuss problems involved in finding locations suitable for geological (paleoseismological) studies for the determination of the timing of recent earthquake ruptures, problems due to both man-made and natural causes.

A meta‐analysis of fault slip rates across the central Apennines

2021 ◽  
Author(s):  
M. M. C. Carafa ◽  
D Di Naccio ◽  
C. Di Lorenzo ◽  
V. Kastelic ◽  
P. Bird
Keyword(s):  
Meta Analysis ◽  
Fault Slip ◽  
Central Apennines ◽  
Slip Rates ◽  
Fault Slip Rates

Multisegment Rupture Hazard Modeling along the Xianshuihe Fault Zone, Southeastern Tibetan Plateau

2020 ◽  
Author(s):  
Jia Cheng ◽  
Thomas Chartier ◽  
Xiwei Xu
Keyword(s):  
Slip Rate ◽  
Historical Earthquakes ◽  
Input Constraints ◽  
Ground Acceleration ◽  
Slip Rates ◽  
Fault Slip Rates ◽  
Seismicity Rates ◽  
Xianshuihe Fault Zone ◽  
Large Earthquakes ◽  
Southern Section

Abstract The Xianshuihe fault is a remarkable strike-slip fault characterized by high slip rate (∼10  mm/yr) and frequent strong historical earthquakes. The potential for future large earthquakes on this fault is enhanced by the 2008 Mw 7.9 Wenchuan earthquake. Previous works gave little attention to the probabilities of multisegment ruptures on the Xianshuihe fault. In this study, we build five possible multisegment rupture combination models for the Xianshuihe fault. The fault slip rates and historical earthquakes are used as input constraints to model the future seismicity on the fault segments and test whether the rupture combination models are appropriate. The segment combination model, based essentially on historical ruptures, has produced the seismicity rates most consistent with the historical records, although the model with ruptures on both the entire northern section and southern section should also be considered. The peak ground acceleration values with a return period of 475 yr calculated using the modeled rates on the Xianshuihe fault for both two models are on average larger than the values of the China Seismic Ground Motion Parameters Zonation Map.

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