Interactions of Earthquakes in Central Italy over the Past 100 Yr through Coulomb Stress Changes, and Implications for Seismic Hazards

2020 ◽  
Vol 110 (1) ◽  
pp. 178-190 ◽  
Author(s):  
Bin Shan ◽  
Yashan Feng ◽  
Chengli Liu ◽  
Xiong Xiong
Keyword(s):  
Central Italy ◽  
Active Faults ◽  
Earthquake Hazard ◽  
Seismic Hazards ◽  
Historical Seismicity ◽  
Normal Faults ◽  
Coulomb Stress Changes ◽  
Earthquake Hazard Assessment ◽  
Stress Changes ◽  
Large Earthquakes

ABSTRACT Italy has a historical earthquake record that is complete for events with a magnitude above 5.8 since A.D. 1349, making it possible to study Coulomb failure stress changes (ΔCFS) over a long period. In this study, we investigated the interactions between moderate-to-large earthquakes through ΔCFS over 100 yr in central Italy. This region is characterized by intense seismicity with predominantly extensional components. Hence, earthquake hazard assessment is of great public concern. Besides, earthquake interactions on normal faults are relatively less studied compared to reverse and strike-slip faults. ΔCFS calculations in this study incorporated both coseismic stress transfer and postseismic viscoelastic relaxation, and found the epicenters of 13 out of 15 events located in positively stressed lobes induced by previous earthquakes, confirming a correlation between the ΔCFS pattern and locations of moderate-to-large earthquakes. Next, we estimated the current distribution of ΔCFS on active faults, and after a comprehensive analysis of ΔCFS accumulation, slip rates, historical seismicity, and locations of populated cities, we identified three regions of potential seismic hazards in this region.

scholarly journals Usefulness of Coulomb Static Stress Changes in Earthquake Hazard Studies: An Example from the Lake Van Area, Eastern Turkey

2021 ◽  
Vol 4 (2) ◽  
pp. 33-41
Author(s):  
Murat Utkucu ◽  
Hatice Durmuş
Keyword(s):  
Earthquake Hazard ◽  
Static Stress ◽  
Coulomb Stress ◽  
Lake Area ◽  
Earthquake Rupture ◽  
Lake Van ◽  
Coulomb Stress Changes ◽  
Calculated Stress ◽  
Stress Changes ◽  
Large Earthquakes

It has been globally documented over different tectonic environments that Coulomb static stress changes caused by a mainshock can promote or demote stresses along the neighboring faults and thus triggers or delays following seismicity. In the present study Coulomb stress changes of the earthquakes in the Lake Van area are calculated using available data and the likely source faults. The calculated stress change maps demonstrate that the large earthquakes in the Lake Area are mostly stressed by the preceding earthquakes, suggesting earthquake rupture interactions. It is further suggested that Coulomb stress maps could be used for constraining the likely locations of the future large earthquakes and in the earthquake hazard mitigation studies.

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

scholarly journals Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5–5.0 seismic sequence of 2016–2017, central Italy

2017 ◽  
Vol 210 (2) ◽  
pp. 1206-1218 ◽  
Author(s):  
Zoe K. Mildon ◽  
Gerald P. Roberts ◽  
Joanna P. Faure Walker ◽  
Francesco Iezzi
Keyword(s):  
Main Shock ◽  
Central Italy ◽  
Stress Transfer ◽  
Historical Record ◽  
Normal Faults ◽  
Coulomb Stress ◽  
Seismic Sequence ◽  
Fault Interaction ◽  
Slip Rates ◽  
Stress Changes

Abstract In 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.

scholarly journals Timor Collision Front Segmentation Reveals Potential for Great Earthquakes in the Western Outer Banda Arc, Eastern Indonesia

2021 ◽  
Vol 9 ◽  
Author(s):  
Aurélie Coudurier-Curveur ◽  
Satish C. Singh ◽  
Ian Deighton
Keyword(s):  
Active Faults ◽  
Accretionary Prism ◽  
Historical Seismicity ◽  
Normal Faults ◽  
Seismic Reflection Data ◽  
Spatially Correlated ◽  
Eastern Indonesia ◽  
The North ◽  
Reflection Data ◽  
Banda Arc

In Eastern Indonesia, the western Outer Banda arc accommodates a part of the oblique Australian margin collision with Eurasia along the Timor Trough. Yet, unlike the Wetar and Alor thrusts of the Inner Banda arc in the north and the adjacent Java subduction zone in the west, both recent and historical seismicity along the Timor Trough are extremely low. This long-term seismic quiescence questions whether the Banda Arc collision front along the Timor Trough is actually fully locked or simply aseismic and raises major concerns on the possible occurrence of large magnitude and tsunamigenic earthquakes in this vulnerable and densely populated region. Here, we jointly analyze multibeam bathymetry and 2D seismic reflection data acquired along the Timor Trough to characterize the location, nature, and geometry of active faults. Discontinuous narrow folds forming a young accretionary prism at the base of the Timor wedge and spatially correlated outcropping normal faults on the bending northwest Australian shelf reveal two concurrent contrasting styles of deformation: underthrusting and frontal accretion. We find that those tectonic regimes and their associated seismic behaviors depend on 1) the thickness of the incoming and underthrusting Cenozoic sedimentary sequence, 2) the vergence of inherited normal faults developed within the continental shelf, and 3) the depth of the décollement beneath the Timor wedge. Based on the along-strike, interchanging distinct deformation style, we identify the mechanical and seismic segmentation along the Banda arc collision front and discuss the implications for earthquake and tsunami hazards along the western Outer Banda arc region.

Preliminary Report on the 18 May 2020 Ms 5.0 Qiaojia Earthquake, Yunnan, China

2021 ◽  
Author(s):  
Zhen Fu ◽  
Changsheng Jiang ◽  
Fengling Yin ◽  
Lei Zhang ◽  
Xuanye Shen ◽  
...  
Keyword(s):  
Stress Field ◽  
Focal Mechanism ◽  
Negative Impact ◽  
Earthquake Hazard ◽  
Focal Mechanisms ◽  
Seismogenic Fault ◽  
Coulomb Stress Changes ◽  
Ludian Earthquake ◽  
Moderate Earthquake ◽  
Stress Changes

Abstract The 18 May 2020 Ms 5.0 Qiaojia earthquake occurred in Qiaojia County, Yunnan Province, ∼25  km away from the 3 August 2014 Ms 6.5 Ludian earthquake. This earthquake was well recorded by dense local seismic stations of the Qiaojia array constructed near the Xiaojiang fault zone. The focal mechanism of the mainshock exhibited strike-slip motion with a centroid depth of 8 km. We determined the seismogenic fault of the Qiaojia earthquake using aftershock relocation with local dense seismic arrays. The mainshock is located on a previously unmapped fault. Aftershocks clearly delineated east–west rupture plane, which was not revealed by the regional seismic network due to relatively sparse stations. The length and width of the aftershock zone are ∼5  km and 3 km, respectively. The focal mechanisms of 70 aftershocks with magnitudes ML≥1.0 showed similar focal mechanism with the mainshock. The stress field inverted from focal mechanisms of the aftershocks is consistent with the tectonic stress field. The coseismic and postseismic static coulomb stress changes show that the Ludian earthquake has a negative impact on the Qiaojia earthquake with a value of −0.01  MPa, implying that the Qiaojia earthquake was unlikely statically triggered by the Ludian earthquake. The Qiaojia earthquake sequence was characterized by low b-value and low-decay rate in the aftershock area, indicating high-seismic risk in this region. The dense seismic observation allows us to study the moderate earthquake in detail and provides us with valuable information of near-fault seismicity to analyze earthquake hazard and the potential of large earthquakes in the future.

Do historical rates of seismicity in southern California require the occurrence of earthquake magnitudes greater than would be predicted from fault length?

1997 ◽  
Vol 87 (6) ◽  
pp. 1662-1666 ◽  
Author(s):  
Mark W. Stirling ◽  
Steven G. Wesnousky
Keyword(s):  
Working Group ◽  
Southern California ◽  
Active Faults ◽  
Historical Seismicity ◽  
Historical Distribution ◽  
Large Earthquakes ◽  
Fault Length

Abstract The Working Group on California Earthquake Probabilities reported a discrepancy between the historical rates of large earthquakes in southern California and rates predicted from interpretation of geological, geodetic, and historical seismicity data. It was suggested that the discrepancy may be due to the assumption within their analysis that the magnitude of the largest earthquake on a fault is limited by the mapped fault length. Our analysis of the available data does not support the presence of a historical deficit in the rate of seismicity, nor does it require that earthquakes that rupture beyond the lengths of mapped active faults in southern California, or that rupture numerous subparallel faults, are needed to explain the historical distribution of seismicity.

Faults distribution and seismogenic potential in the Calabrian back-arc domain, SE Tyrrhenian Sea

2020 ◽  
Author(s):  
Camilla Palmiotto ◽  
Maria Filomena Loreto ◽  
Francesco Muto ◽  
Valentina Ferrante ◽  
Franco Pettenati ◽  
...  
Keyword(s):  
Active Faults ◽  
Normal Fault ◽  
Historical Seismicity ◽  
Normal Faults ◽  
Transitional Region ◽  
Tyrrhenian Sea ◽  
Seismic Profiles ◽  
Offshore Area ◽  
Fault Systems ◽  
Back Arc

<p>The Western Calabrian margin (Italy) is the most active segment of the Apennine back-arc system, formed in response to the slow Africa – Eurasia convergence. The offshore area represents the transitional region between the arc and the back-arc: it is affected by several fault systems, most of them able to trigger highly destructive earthquakes. Indeed, the Calabria and its western offshore are characterized by the highest seismic moment release of the entire Apennines, also evidenced by historical seismicity catalogue, the most accurate over the world. During last decades, scientific community invested huge resources in assessment of seismic and tsunami hazards. Furthermore, during last years several local-scale works allowed of improving knowledge of the faults geometry, magmatism, seismogenic and tsunamigenic potential along the western offshore region (Loreto et al., 2017; Brutto et al., 2016; De Ritis et al., 2019). Some active faults, belonging to NE-SW-trending normal fault systems accommodating the inner-arc collapse related to slab-decupling, are also responsible of the most destructive historical sequences, still to be adequately characterized. Using vintage SPARKER 30 Kj acquired in the seventies and recent multichannel seismic profiles together with middle resolution morpho-bathymetric data we produced a new tectonic map of the Calabria back-arc system. Further, we characterized some before-unknown faults and linked them with shallow structures, as ridges and slumps / slides. This area seemingly less populated of faults compared to the peri-Tyrrhenian margin, where several faults belong to different systems, i.e. (i) the rifting system active that allowed the opening of the Tyrrhenian Basin and (ii) the slab-decupling related normal faults system currently active. The comparison with historical and instrumental seismicity allowed us to highlight possible seismic gaps that, if considered, could strongly improve the map of seismogenic potential of the Tyrrhenian back-arc system.</p><p> </p><p>Bibliography</p><p>Brutto, F. et al. (2016). The Neogene-Quaternary geodynamic evolution of the central Calabrian Arc: A case study from the western Catanzaro Trough basin. Journal of Geodynamics, 102, 95-114.</p><p>Loreto, M. F. (2017). Reconstructed seismic and tsunami scenarios of the 1905 Calabria earthquake (SE Tyrrhenian sea) as a tool for geohazard assessment. Engineering geology, 224, 1-14.</p><p>Tripodi, V. et al. (2018). Neogene-Quaternary evolution of the forearc and backarc regions between the Serre and Aspromonte Massifs, Calabria (southern Italy). Marine and Petroleum Geology, 95, 328-343.</p>

Geodetic Model of the 2018 Mw 7.2 Pinotepa, Mexico, Earthquake Inferred from InSAR and GPS Data

2020 ◽  
Vol 110 (3) ◽  
pp. 1115-1124 ◽  
Author(s):  
Yanchuan Li ◽  
Xinjian Shan ◽  
Chuanhua Zhu ◽  
Xin Qiao ◽  
Lei Zhao ◽  
...  
Keyword(s):  
Time Series Data ◽  
Source Parameters ◽  
Source Region ◽  
Seismogenic Zone ◽  
Series Data ◽  
Gps Data ◽  
Earthquake Hazard Assessment ◽  
Stress Changes ◽  
Mexico Earthquake ◽  
Large Earthquakes

ABSTRACT Investigating the interaction between slow-slip events (SSEs) and large earthquakes provides insights into earthquake-triggering mechanisms and is crucial for earthquake hazard assessment. In this study, we used Sentinel-1 Interferometric Synthetic Aperture Radar and Global Positioning System (GPS) data to estimate the source parameters of the 2018 Mw 7.2 Pinotepa, Mexico, earthquake. The results show that the earthquake ruptured both the seismogenic zone and a long-term SSE area, with two asperities ruptured during the event. GPS time-series data indicate that an SSE was initiated approximately during March 2017 below Oaxaca; the SSE ruptured an area below the source region of the Pinotepa earthquake and intruded into the seismogenic zone. The spatiotemporal proximity may suggest that the SSE triggered the Pinotepa earthquake. We propose that the triggering mechanism may either have been Coulomb stress loading or weakening of the source area by fluid migration. Furthermore, we calculated the seismic moment deficit and Coulomb failure stress changes and conclude that the Oaxaca area still has the potential for large earthquakes.

scholarly journals Decades of Ground Deformation in the Weihe Graben, Shaanxi Province, China, in Response to Various Land Processes, Observed by Radar Interferometry and Levelling

2021 ◽  
Vol 13 (12) ◽  
pp. 2374
Author(s):  
Jianlong Chen ◽  
Yu Zhou ◽  
Gan Chen ◽  
Ming Hao
Keyword(s):  
Ground Deformation ◽  
Average Rate ◽  
Anthropogenic Activities ◽  
Active Faults ◽  
Shaanxi Province ◽  
Tectonic Deformation ◽  
Coulomb Stress ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
Weihe Graben

Ground deformation is usually used as direct evidence for early warning of geological hazards. The Weihe Graben, located in the southern margin of the Ordos Plateau, is surrounded by many active faults. Earthquakes (e.g., the 1556 Huaxian M 8 earthquake), mine accidents and ground fissures are the major hazards that pose great threats to this densely populated region. In order to characterise both tectonic and anthropogenic activities in the Weihe Graben, we use Envisat data from 2003 to 2010 and Sentinel-1 data from 2014 to 2021, combined with levelling data from 1970 to 2014, to investigate the long-term ground deformation. We generate four InSAR rate maps using the small-baseline subset (SBAS) algorithm. The uncertainties of the InSAR rates are 1–2 mm/year by calculating the differences between the InSAR and levelling measurements. From the deformation time series, we found that most of the faults surrounding the Weihe Graben move at a relatively slow rate (<3 mm/year). Elastic dislocation modelling based on the InSAR and levelling data yields a slip rate of 2.3 ± 0.3 mm/year for the Huashan Fault, the seismogenic fault for the 1556 Huaxian earthquake. Anthropogenic deformation is much stronger than the tectonic deformation. We identified localised subsidence of 12 mines with a deformation rate ranging from 5 to 17 mm/year. The cities of Xi’an and Xianyang also show evident subsidence, which is likely to be caused by groundwater extraction. Land subsidence in Xi’an has slowed down from an average rate of 10–20 mm/year between 2003 and 2010 to about 5–10 mm/year between 2017 and 2020, but in Xianyang, subsidence has increased dramatically in the past five years from 1 mm/year to 7 mm/year. This is because new industrial and urban development centres have gradually moved from Xi’an to Xianyang. We identified a region bounded by the Kouzhen-Guanshan and Fufeng-Liquan Faults with strong subsidence, as a result of excessive extraction of groundwater. To quantify the effects of crustal groundwater unloading on faults, we calculated the static Coulomb stress changes on the two faults and found that Coulomb stress changes are localised in the upper 5 km with a magnitude of 0.01–0.02 bar/year. The Coulomb stress changes might be large enough (0.1 bar) to affect local seismicity if such excessive extraction of groundwater continued for 10 years.

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