61 research outputs found
Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: TheMw 6.5-5.0 seismic sequence of 2016-2017, central Italy
No full textIn order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August-October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)).We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316-4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016-2017 A.D. sequence. We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main-shock ruptures
Coseismic Throw Variation Across Along-Strike Bends on Active Normal Faults: Implications for Displacement Versus Length Scaling of Earthquake Ruptures
No full textFault bends, and associated changes in fault dip, play a key role in explaining the scatter in maximum offset versus surface rupture length fault scaling relationships. Detailed field measurements of the fault geometry and magnitude of slip in the 2016–2017 Central Italy earthquake sequence, alongside three examples from large historical normal-faulting earthquakes in different tectonic settings, provide multiple examples in which coseismic throw increases across bends in fault strike where dip also increases beyond what is necessary to accommodate a uniform slip vector. Coseismic surface ruptures produced by two mainshocks of the 2016–2017 Central Italy earthquake sequence (24 August 2016 Mw 6.0 and 30 October 2016 Mw 6.5) cross a ~0.83-km amplitude along-strike bend, and the coseismic throws for both earthquakes increase by a factor of 2–3, where the strike of the fault changes by ~28o and the dip increases by 20–25o. We present similar examples from historical normal faulting earthquakes (1887, Sonora earthquake, Mw 7.5; 1981, Corinth earthquakes, Mw 6.7–6.4; and 1983, Borah Peak earthquake, Mw 7.3). We demonstrate that it is possible to estimate the expected change in throw across a bend by applying equations that relate strike, dip, and slip vector to horizontal strain conservation along a nonplanar fault for a single earthquake rupture. The calculated slip enhancement in bends can explain much of the scatter in maximum displacement (Dmax) versus surface rupture length scaling relationships. If fault bends are unrecognized, they can introduce variation in Dmax that may lead to erroneous inferences of stress drop variability for earthquakes, and exaggerate maximum earthquake magnitudes derived from vertical offsets in paleoseismic data sets
A shallow earthquake swarm close to hydrocarbon activities: discriminating between natural and induced causes for the 2018–19 Surrey, UK earthquake sequence
No full textEarthquakes induced by subsurface industrial activities are a globally emotive issue, with a growing catalogue of induced earthquake sequences. However, attempts at discriminating between natural and induced causes, particularly for anomalously shallow seismicity, can be challenging. An earthquake swarm during 2018–19 in south-east England with a maximum magnitude of ML 3.2 received great public and media attention because of its proximity to operating oilfields. It is therefore vital and timely to provide a
detailed characterisation of the earthquake sequence at present, and to decide based on current evidence, whether the earthquakes were likely natural or induced. We detected 168 low-magnitude earthquakes and computed detailed source parameters of these events. Most earthquakes occurred at a shallow depth of 2.3 km, >1 km deeper than the
geological formations targeted by the oilfields, and laterally >3 km away from the drillsites. We combine the east-west trending cluster of the seismicity with 2-D seismic reflection profiles to find the causative fault system for the earthquakes. A b-value close to unity and strike-slip faulting mechanisms are consistent with tectonic reactivation along a pre-existing fault. Overall, we find no indicators in the earthquake parameters that would strongly suggest an induced source. Nor do we find any clear trends between seismicity
and drilling activities based on operational logs provided by the operators. Injected volumes are near-zero and monthly production amounts are many orders of magnitude smaller than other reported cases of extraction-induced seismicity. On balance, and based on the available evidence, we find it currently unlikely that nearby industrial activities induced the seismic swarm. Most likely, the Surrey earthquakes offer a uniquely detailed insight into shallow seismicity within sedimentary basins. Nevertheless, selfreporting of injection and production times and volumes by operators, and the lack of easily- and publicly-available oilfield operational data continues to be a point of concern for local residents
Interseismic Strain Rate Evolution From InSAR Prior to the 2021 Mw 7.4 Maduo Earthquake
No full textThis repository contains the datasets from the supporting information for the manuscript: Rutland, C., Bie, L., Johnson, J.H., Ou, Q. & Mildon, Z.K. (2024). "Interseismic Strain Rate Evolution From InSAR Prior to the 2021 Mw 7.4 Maduo Earthquake." Data Set S1. V E derived from InSAR data from 2015/01/28–2021/05/20. Data Set S2. σV E derived from InSAR data from 2015/01/28–2021/05/20. Data Set S3. ε̇ shear derived from InSAR data from 2015/01/28–2021/05/20. Data Set S4. V E derived from InSAR data from 2015/01/28–2017/05/17. Data Set S5. σV E derived from InSAR data from 2015/01/28–2017/05/17. Data Set S6. ε̇ shear derived from InSAR data from 2015/01/28–2017/05/17. Data Set S7. V E derived from InSAR data from 2017/05/29–2019/05/19. Data Set S8. σV E derived from InSAR data from 2017/05/29–2019/05/19. Data Set S9. ε̇ shear derived from InSAR data from 2017/05/29–2019/05/19. Data Set S10. V E derived from InSAR data from 2019/05/31–2021/05/20. Data Set S11. σV E derived from InSAR data from 2019/05/31–2021/05/20. Data Set S12. ε̇ shear derived from InSAR data from 2019/05/31–2021/05/20.Rutland, C., Bie, L., Johnson, J., Ou, Q., & Mildon, Z. (2024). Interseismic Strain Rate Evolution From InSAR Prior to the 2021 Mw 7.4 Maduo Earthquake [Data set]. Zenodo. https://doi.org/10.5281/zenodo.1369253
A European union and Canadian review of public health nursing preparation and practice.
No full textThis study explores the preparation and role of the public health nurse (PHN) across European Union (EU) countries (Finland, Sweden, and the United Kingdom) and Canadian provinces (Alberta, New Brunswick, and Prince Edward Island)
О философской лирике Гавилы Державинa
No full textAbout Gavrila Derzhavin’s philosophical lyricsThe author examines Derzhavin as the first Russian poet who expressed the main problems of social being. He may be considered a creator of the philosophic tradition in Russian lyric poetry. Derzhavin turned poetic creation into an esthetic phenomenon instead of a service to the czar. It became independent from monarch’s mood and political interests. Russian poetry from Pushkin to Zabolotsky used his experience.About Gavrila Derzhavin’s philosophical lyricsThe author examines Derzhavin as the first Russian poet who expressed the main problems of social being. He may be considered a creator of the philosophic tradition in Russian lyric poetry. Derzhavin turned poetic creation into an esthetic phenomenon instead of a service to the czar. It became independent from monarch’s mood and political interests. Russian poetry from Pushkin to Zabolotsky used his experience
Slip on a mapped normal fault for the 28th December 1908 Messina earthquake (Mw 7.1) in Italy
No full textThe 28th December 1908 Messina earthquake (Mw 7.1), Italy, caused >80,000 deaths and transformed
earthquake science by triggering the study of earthquake environmental effects worldwide, yet its
source is still a matter of debate. To constrain the geometry and kinematics of the earthquake we use
elastic half-space modelling on non-planar faults, constrained by the geology and geomorphology of
the Messina Strait, to replicate levelling data from 1907–1909. The novelty of our approach is that we
(a) recognise the similarity between the pattern of vertical motions and that of other normal faulting
earthquakes, and (b) for the first time model the levelling data using the location and geometry of a
well-known offshore capable fault. Our results indicate slip on the capable fault with a dip to the east of
70° and 5 m dip-slip at depth, with slip propagating to the surface on the sea bed. Our work emphasises
that geological and geomorphological observations supporting maps of capable non-planar faults
should not be ignored when attempting to identify the sources of major earthquakes
Co-seismic and shallow post-seismic slip during the 2016 central Italy earthquake sequence revealed by differential terrestrial laser scanning and photogrammetry
No full textRegional Deformation and Offshore Crustal Local Faulting as Combined Processes to Explain Uplift Through Time Constrained by Investigating Differentially Uplifted Late Quaternary Paleoshorelines: The Foreland Hyblean Plateau, SE Sicily
No full textQuaternary uplift is well documented in SE Sicily, a region prone to damaging seismic events, such as the 1693 “Val di Noto” earthquake (Mw 7.4), the largest seismic event reported within the Italian Earthquake Catalogue, whose seismogenic source is still debated and, consequently, the long-term seismic hazard is poorly understood. However, the spatial variation in the timing and rates of uplift are still debated, so it is difficult to link the dominant tectonic process(es) responsible for the uplift and the location of seismogenic sources. To better constrain the uplift rate, we have refined the dating of Late Quaternary marine terraces, using a synchronous correlation approach, driven by both published and newly obtained numerical age controls (234U/230Th dating on corals). This has allowed recalculation of uplift rates along a N-S oriented transect within the Hyblean Plateau (HP) foreland region. Consequently, we have mapped the geometry of paleoshorelines along a coastline-parallel transect and hence the rates of uplift. The results suggest increasing uplift rate from south to north across the HP and that uplift rates have remained constant through the Late Quaternary. This spatially changing but temporally constant uplift places constraints on the proportion of uplift produced by regional geodynamic processes versus produced by local faults, such as an offshore east dipping active normal fault. We discuss these new findings in terms of the long-term seismic hazard for one of the most seismically active regions in the Mediterranean Basin
Out of phase Quaternary uplift-rate changes reveal normal fault interaction, implied by deformed marine palaeoshorelines
No full textWe have mapped and constrained the timing of tectonically deformed uplifted Late Quaternary palaeoshorelines in the Messina Strait, southern Italy, an area above a subduction zone containing active normal faults. The palaeoshorelines are preserved from up to thirteen Late Quaternary sea-level highstands, providing a record of the deformation over this timescale (~500 ka) for the Messina-Taormina Fault, the Reggio Calabria Fault and the Armo Fault. The palaeoshorelines reveal spatial patterns of uplift through time along the strike of these normal faults, and, given the across strike arrangement of the faults, also reveal how the contribution of each fault to the regional strain-rate progressed through time. The results reveal that the uplift rates mapped within the fault hangingwalls and footwalls were not constant through time, with a marked change in the location of strain accumulation at ~50 ka. The uplift rates, once converted into throw-rates, imply that the three faults comprised similar throw-rates prior to ~50 ka (in the range 0.77–0.96 mm/yr), with the Armo and Reggio Calabria faults then switching to lower rates (0.32 mm/yr and 0.33 mm/yr respectively), whilst the Messina-Taormina Fault accelerated to 2.34 mm/yr. The regional extension rate, gained by summing the implied heave rates across the three faults, was maintained through time despite this re-organisation of local strain accumulation at ~50 ka. We explain these out-of-phase fault throw-rate changes during the constant-rate regional extension conditions as due to interactions between these upper plate normal faults. We finally discuss how fault throw-rates changing through time may affect a long-term seismic hazard assessment within active normal fault systems
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