Identification of the seismogenic source of the 1875 Cucuta earthquake on the basis of a combination of neotectonic, paleoseismologic and historic seismicity studies

2018 ◽  
Vol 82 ◽  
pp. 274-291 ◽  
Author(s):  
Luz Rodríguez ◽  
Hans Diederix ◽  
Eliana Torres ◽  
Franck Audemard ◽  
Catalina Hernández ◽  
...  
Keyword(s):  
Seismogenic Source ◽  
Historic Seismicity

scholarly journals Liquefaction phenomena associated with the Emilia earthquake sequence of May–June 2012 (Northern Italy)

2013 ◽  
Vol 13 (4) ◽  
pp. 935-947 ◽  
Author(s):  
Keyword(s):  
Structural Characteristics ◽  
High Water ◽  
Web Based ◽  
Geological Evidence ◽  
Po Plain ◽  
Emilia Earthquake ◽  
Blind Thrust ◽  
Empirical Relations ◽  
Seismogenic Source ◽  
Deformation Area

Abstract. In this paper we present the geological effects induced by the 2012 Emilia seismic sequence in the Po Plain. Extensive liquefaction phenomena were observed over an area of ~ 1200 km2 following the 20 May, ML 5.9 and 29 May, ML 5.8 mainshocks; both occurred on about E–W trending, S dipping blind thrust faults. We collected the coseismic geological evidence through field and aerial surveys, reports from local people and Web-based survey. On the basis of their morphologic and structural characteristics, we grouped the 1362 effects surveyed into three main categories: liquefaction (485), fractures with liquefaction (768), and fractures (109). We show that the quite uneven distribution of liquefaction effects, which appear concentrated and aligned, is mostly controlled by the presence of paleo-riverbeds, out-flow channels and fans of the main rivers crossing the area; these terrains are characterised by the pervasive presence of sandy layers in the uppermost 5 m, a local feature that, along with the presence of a high water table, greatly favours liquefaction. We also find that the maximum distance of observed liquefaction from the earthquake epicentre is ~ 30 km, in agreement with the regional empirical relations available for the Italian Peninsula. Finally, we observe that the contour of the liquefaction observations has an elongated shape almost coinciding with the aftershock area, the InSAR deformation area, and the I ≥ 6 EMS area. This observation confirms the control of the earthquake source on the liquefaction distribution, and provides useful hints in the characterisation of the seismogenic source responsible for historical and pre-historical liquefactions.

scholarly journals Time independent seismic hazard analysis of Greece deduced from Bayesian statistics

2003 ◽  
Vol 3 (1/2) ◽  
pp. 129-134 ◽  
Author(s):  
T. M. Tsapanos ◽  
G. A. Papadopoulos ◽  
O. Ch. Galanis
Keyword(s):  
Seismic Hazard ◽  
Bayesian Statistics ◽  
Hazard Analysis ◽  
Earthquake Occurrence ◽  
Time Intervals ◽  
Seismogenic Sources ◽  
Earthquake Resistant Design ◽  
Seismogenic Source ◽  
Earthquake Resistant ◽  
Of Greece

Abstract. A Bayesian statistics approach is applied in the seismogenic sources of Greece and the surrounding area in order to assess seismic hazard, assuming that the earthquake occurrence follows the Poisson process. The Bayesian approach applied supplies the probability that a certain cut-off magnitude of Ms = 6.0 will be exceeded in time intervals of 10, 20 and 75 years. We also produced graphs which present the different seismic hazard in the seismogenic sources examined in terms of varying probability which is useful for engineering and civil protection purposes, allowing the designation of priority sources for earthquake-resistant design. It is shown that within the above time intervals the seismogenic source (4) called Igoumenitsa (in NW Greece and west Albania) has the highest probability to experience an earthquake with magnitude M > 6.0. High probabilities are found also for Ochrida (source 22), Samos (source 53) and Chios (source 56).

Seismogenic source model of the 2019 Mw 5.9 East-Azerbaijan earthquake (NW Iran) through Sentinel-1 DInSAR measurements

2020 ◽  
Author(s):  
Emanuela Valerio ◽  
Francesco Casu ◽  
Vincenzo Convertito ◽  
Claudio De Luca ◽  
Vincenzo De Novellis ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Seismic Source ◽  
Source Model ◽  
Fault Model ◽  
Strike Slip ◽  
Coseismic Deformation ◽  
Lateral Strike Slip ◽  
Nw Iran ◽  
Seismogenic Source ◽  
East Azerbaijan

<p>On 7 November 2019 (22:47 UTC) a M<sub>w</sub> 5.9 earthquake struck the East-Azerbaijan region, in the north-western Iran, about 100 km east of Tabriz, the fourth largest city of Iran with a population of over two million. This seismic event caused both widespread damage to the surrounding villages and casualties, killing about 5 people and injuring hundreds. The occurrence of this earthquake is related to the main geodynamic regime controlled by the oblique Arabia-Eurasia convergence and, in particular, this event is inserted in the tectonic context of the East-Azerbaijan Plateau, a complex mountain belt that contains internal major fold-and-thrust belts.</p><p>In this work, we first generate the coseismic deformation maps by applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to SAR data collected along ascending and descending orbits by the Sentinel-1 constellation of the European Copernicus Programme. Then, we invert them through analytical modeling in order to better constrain the geometry and characteristics of the main source. The retrieved fault model revealed a shallow seismic source approximately NE–SW-striking and characterized by a left-lateral strike-slip, southeast-dipping faulting mechanism. Our retrieved solution reveals a new minor fault never mapped in geological maps before, whose kinematics is compatible with that of the surrounding structures and with the local and regional stress states. Moreover, we also use the preferred fault model to calculate the Coulomb Failure Function at the nearby receiver faults; taking into account the surrounding geological structures reported in literature, we show that all the considered receiver faults have been positively stressed by the main event. This is also confirmed by the distribution of the aftershocks that occurred near the considered faults. The analysis of the earthquake nucleated along these left-lateral strike-slip minor fault is essential to improve our knowledge of the East-Azerbaijan Plateau; therefore, further studies are required to evaluate their role in seismic hazard definition of northwest of Iran, in order to help in the mitigation of the seismic hazard in seismogenic regions unprepared for the occurrence of seismic events.</p><p><em>This work is supported by: the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement, H2020 EPOS-SP (GA 871121), ENVRI-FAIR (GA 824068) projects, and the I-AMICA (PONa3_00363) project.</em></p>

scholarly journals Relationship between seismicity and active faults in Thanh Hoa province detected by local seismic network

2021 ◽  
Vol 43 (2) ◽  
pp. 199-219
Author(s):  
Duong T. N. ◽  
Lai Hop Phong ◽  
Pham D. N. ◽  
Chen C. H. ◽  
Dinh V. T.
Keyword(s):  
Seismic Activity ◽  
Active Faults ◽  
Seismic Network ◽  
Local Network ◽  
Ground Acceleration ◽  
Magnetotelluric Data ◽  
Seismogenic Source ◽  
Tectonically Active ◽  
Relationship Of ◽  
The Relationship

Thanh Hoa province belongs to the southwest part of Northwest Vietnam, which is considered a tectonically active region. In the area of Thanh Hoa province, there are three deep-seated tectonic faults, namely Son La-Bim Son, Song Ma, and Sop Cop. As predicted by scientists, these faults are capable of producing credible earthquakes that might be the strongest in the territory of Vietnam. Besides the three main seismogenic sources, in the province, there are other smaller active faults such as Thuong Xuan-Ba Thuoc and Thuong Xuan-Vinh Loc but the relationship of these faults with seismic activity is still rather blurred. This may due to the sparseness of the Vietnamese National Seismic Network which can not record adequately small earthquakes in the area. This paper presents new results of additional monitoring from a local seismic network using 12 Guralp - 6TD broadband seismometers that have been deployed in Thanh Hoa province since November 2009. We found that the Thanh Hoa area is not seismically quiet. The average number of earthquakes recorded by the network has reached 80 - 90 events per year and some of them have magnitude from ML 3.0 to 4.0.By integration of the earthquake epicenters derived from the local network and distribution of active faults, we can detect several earthquakes locating near the three active faults, not only along the main faults but also along its subsidiary faults. We focused on the active faults of Thuong Xuan-Ba Thuoc and Thuong Xuan-Vinh Loc by using the recent results of the gravity, seismic, and magnetotelluric data analyses. Several recorded earthquakes distribute along the two small faults and some of them reach magnitude 3.0 or greater on the ML scale. In this study, the Thuong Xuan-Vinh Loc is recognized as a seismogenic source. To identify seismic hazard potential caused by earthquakes generated from the active faults, segmentation of the Thuong Xuan - Ba Thuoc fault had been done based on geological and geomorphological indications and seismic activity, and then the peak ground acceleration was determined for each fault segment. Besides, a large number of earthquake epicenters do not have a good correlation with a specific fault, especially in the area of Thanh Hoa coastal plain, which is covered by thick layers of Neogene - Quaternary sediment. This shows that there may be hidden active faults in the area which are needed to study further.

scholarly journals Multiple Lines of Evidence for a Potentially Seismogenic Fault Along the Central-Apennine (Italy) Active Extensional Belt–An Unexpected Outcome of the MW6.5 Norcia 2016 Earthquake

2021 ◽  
Vol 9 ◽  
Author(s):  
Federica Ferrarini ◽  
Rita de Nardis ◽  
Francesco Brozzetti ◽  
Daniele Cirillo ◽  
J Ramón Arrowsmith ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Tectonic Setting ◽  
Central Italy ◽  
Stress Transfer ◽  
Normal Fault ◽  
Normal Faults ◽  
Coulomb Stress ◽  
Seismic Sequence ◽  
Seismogenic Fault ◽  
Seismogenic Source

The Apenninic chain, in central Italy, has been recently struck by the Norcia 2016 seismic sequence. Three mainshocks, in 2016, occurred on August 24 (MW6.0), October 26 (MW 5.9) and October 30 (MW6.5) along well-known late Quaternary active WSW-dipping normal faults. Coseismic fractures and hypocentral seismicity distribution are mostly associated with failure along the Mt Vettore-Mt Bove (VBF) fault. Nevertheless, following the October 26 shock, the aftershock spatial distribution suggests the activation of a source not previously mapped beyond the northern tip of the VBF system. In this area, a remarkable seismicity rate was observed also during 2017 and 2018, the most energetic event being the April 10, 2018 (MW4.6) normal fault earthquake. In this paper, we advance the hypothesis that the Norcia seismic sequence activated a previously unknown seismogenic source. We constrain its geometry and seismogenic behavior by exploiting: 1) morphometric analysis of high-resolution topographic data; 2) field geologic- and morphotectonic evidence within the context of long-term deformation constraints; 3) 3D seismological validation of fault activity, and 4) Coulomb stress transfer modeling. Our results support the existence of distributed and subtle deformation along normal fault segments related to an immature structure, the Pievebovigliana fault (PBF). The fault strikes in NNW-SSE direction, dips to SW and is in right-lateral en echelon setting with the VBF system. Its activation has been highlighted by most of the seismicity observed in the sector. The geometry and location are compatible with volumes of enhanced stress identified by Coulomb stress-transfer computations. Its reconstructed length (at least 13 km) is compatible with the occurrence of MW≥6.0 earthquakes in a sector heretofore characterized by low seismic activity. The evidence for PBF is a new observation associated with the Norcia 2016 seismic sequence and is consistent with the overall tectonic setting of the area. Its existence implies a northward extent of the intra-Apennine extensional domain and should be considered to address seismic hazard assessments in central Italy.

scholarly journals Earthquakes of 1838 and 1839 in the Slovene Hills (Slovenia)-Međimurje (Croatia) area

Geofizika ◽  
2021 ◽  
Vol 38 (1) ◽  
pp. 37-59
Author(s):  
Marijan Herak ◽  
Davorka Herak ◽  
Iva Vrkić ◽  
Mladen Živčić
Keyword(s):  
Moment Magnitude ◽  
Sources Of Information ◽  
Research Papers ◽  
Seismogenic Source ◽  
Seismicity Rates ◽  
Travel Books ◽  
North Eastern ◽  
The Town ◽  
Macroseismic Parameters ◽  
North Western

Analyses of available data (newspaper reports, historical and church chronicles, chronical earthquake overviews, travel books, monographies, research papers, etc.) on effects of the earthquakes that shook the greater Ormož area at the Slovenian-Croatian border in the 1838 and 1839 revealed that one of them, recorded in a number of regional and global catalogues, is in fact a fake - the earthquake of 26 August 1838 never happened. This error creeped into various reports and studies, and then into many relevant catalogues, so this event should by systematically erased from the catalogues used to estimate seismicity rates in the neighbourhoods of north-western Croatia, north-eastern Slovenia, and south-western Hungary.Regarding the earthquake of 31 July 1838, we used important new sources of information that have not been consulted in any previous study. This made inversion of macroseismic parameters more robust. Our estimates of the macroseismic moment magnitude (Mwm = 4.8) is mostly higher than the values reported in the available catalogues. Reliable information on the effects of the smaller event of 22 March 1839 were found for two localities only, so its epicentre was placed into the town of Ormož where the maximum intensity was observed. Its estimated moment magnitude (Mwm) is close to the median of values found in the six consulted catalogues that listed this event.The macroseismic epicentre of the 1838 earthquake lies close to the junction of surface traces of the Donat strike-slip fault and the reverse Čakovec fault. Based on their assumed geometry and the location of the macroseismic hypocentre, we give slight preference to the Donat fault as the seismogenic source.

scholarly journals Clues to the identification of a seismogenic source from environmental effects: the case of the 1905 Calabria (Southern Italy) earthquake

2009 ◽  
Vol 9 (6) ◽  
pp. 1787-1803 ◽  
Author(s):  
A. Tertulliani ◽  
L. Cucci
Keyword(s):  
Environmental Effects ◽  
Southern Italy ◽  
Environmental Changes ◽  
Source Parameters ◽  
Normal Fault ◽  
Rock Falls ◽  
Offshore Area ◽  
Hydrological Changes ◽  
Seismogenic Source ◽  
Ground Effects

Abstract. The 8 September 1905 Calabria (Southern Italy) earthquake belongs to a peculiar family of highly destructive (I0=XI) seismic events, occurred at the dawning of the instrumental seismology, for which the location, geometry and size of the causative source are still substantially unconstrained. During the century elapsed since the earthquake, previous Authors identified three different epicenters that are more than 50 km apart and proposed magnitudes ranging from M≤6.2 to M=7.9. Even larger uncertainties were found when the geometry of the earthquake source was estimated. In this study, we constrain the magnitude, location and kinematics of the 1905 earthquake through the analysis of the remarkable environmental effects produced by the event (117 reviewed observations at 73 different localities throughout Calabria). The data used in our analysis include ground effects (landslides, rock falls and lateral spreads) and hydrological changes (streamflow variations, liquefaction, rise of water temperature and turbidity). To better define the magnitude of the event we use a number of empirical relations between seismic source parameters and distribution of ground effects and hydrological changes. In order to provide constraints to the location of the event and to the geometry of the source, we reproduce the coseismic static strain associated with different possible 1905 causative faults and compare its pattern to the documented streamflow changes. From the analysis of the seismically-induced environmental changes we find that: 1) the 1905 earthquake had a minimum magnitude M=6.7; 2) the event occurred in an offshore area west of the epicenters proposed by the historical seismic Catalogs; 3) it most likely occurred along a 100° N oriented normal fault with a left-lateral component, consistently with the seismotectonic setting of the area.

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