The Bystrinskoe Earthquake in the Southern Baikal Region (21 September 2020, M w = 5.4): Main Parameters, Precursors, and Accompanying Effects

2021 ◽  
Vol 62 (5) ◽  
pp. 589-603
Author(s):  
K.Zh. Seminsky ◽  
S.A. Bornyakov ◽  
A.A. Dobrynina ◽  
N.A. Radziminovich ◽  
S.V. Rasskazov ◽  
...  
Keyword(s):  
Baikal Region ◽  
Seismic Event ◽  
Strike Slip ◽  
Comprehensive Analysis ◽  
East Siberia ◽  
Epicentral Area ◽  
Strong Earthquakes ◽  
Large Cities ◽  
Strike Slip Movement ◽  
Natural Territory

Abstract ––We present the preliminary results of a study of the Bystrinskoe earthquake, which occurred in the southern Baikal region on 21 September 2020 and was accompanied by shaking with an intensity of VI–VII on the MSK-64 scale in the epicentral area and with an intensity of V in large cities of southern East Siberia (Irkutsk, Angarsk, Usolye-Sibirskoe, Zakamensk, etc.). A preliminary characteristic of the seismic event is given on the basis of a comprehensive analysis of seismological, structural-tectonic, strain, emanation, and hydrogeochemical data obtained during the monitoring of hazardous geologic processes in the Baikal natural territory. We have estimated the seismologic parameters of the Bystrinskoe earthquake, characterized the accompanying phenomena, and identified the effects that are of interest as probable precursors of future strong earthquakes in the Baikal region. The data obtained suggest that the earthquake occurred in the zone of the Main Sayan Fault as a result of strike-slip movement along the W–NW fault. The earthquake focus was apparently located at a shallow depth, as evidenced by the duration of the shocks, macroseismic manifestations, and the strong rumble heard at different directions from the epicenter.

The Quebec–Maine Border Earthquake, 15 June 1973

1975 ◽  
Vol 12 (11) ◽  
pp. 1917-1928 ◽  
Author(s):  
R. J. Wetmiller
Keyword(s):  
New England ◽  
Focal Mechanism ◽  
Appalachian Mountains ◽  
Strike Slip ◽  
Maximum Intensity ◽  
Focal Mechanism Solution ◽  
Epicentral Area ◽  
Eastern Ontario ◽  
Shallow Focus ◽  
Strike Slip Movement

On 15 June 1973, a shallow-focus earthquake with magnitude mb 4.8 occurred in southern Quebec, in an area that has a record of only a few minor earthquakes during the previous 200 years. This event was felt throughout southern Quebec, eastern Ontario, and the New England States, to a distance of 300 km from the epicenter. A small amount of minor damage to plaster and chimneys occurred in the immediate epicentral area, indicating a maximum intensity of VI. The focal mechanism solution suggests that the earthquake was the result of primarily strike-slip movement along a plane trending northeast or a plane trending northwest. Arguments are presented that this event is part of the seismicity associated with the northern Appalachian Mountains.

scholarly journals Atmospheric temperature coherent variations effects, preceding strong earthquakes

2020 ◽  
Vol 223 ◽  
pp. 03015
Author(s):  
Leonid Sverdlik ◽  
Sanjar Imashev
Keyword(s):  
Seismic Event ◽  
Atmospheric Temperature ◽  
Tien Shan ◽  
Abnormal Behavior ◽  
Satellite Measurements ◽  
Epicentral Area ◽  
Strong Earthquakes ◽  
Upper Troposphere ◽  
Short Period ◽  
Northern Tien Shan

We analyzed satellite measurements of temperature at upper troposphere/lower stratosphere (UTLS) levels separated by the tropopause above the epicentral area of a strong earthquake with a magnitude of M=7.3 in the Northern Tien-Shan (Kyrgyzstan) that took place on August 19, 1992. The developed algorithm and method of continuous wavelet transform allowed detecting of abnormal behavior, temporal, spatial and spectral coherence of short-period temperature variations, preceding the seismic event. The results show that the spatial structure and dynamics of temperature anomalies in the area of UTLS have a sufficiently stable relation to seismic activity.

scholarly journals ‘Conjugate’ coseismic surface faulting related with the 29 December 2020, Mw 6.4, Petrinja earthquake (Sisak-Moslavina, Croatia)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Emanuele Tondi ◽  
Anna Maria Blumetti ◽  
Mišo Čičak ◽  
Pio Di Manna ◽  
Paolo Galli ◽  
...  
Keyword(s):  
Relevant Information ◽  
Strike Slip ◽  
Secondary Effects ◽  
Epicentral Area ◽  
Field Surveys ◽  
Fundamental Information ◽  
Tension Cracks ◽  
Transcurrent Faults ◽  
Conjugate Fault ◽  
Geometry And Kinematics

AbstractWe provide here a first-hand description of the coseismic surface effects caused by the Mw 6.4 Petrinja earthquake that hit central Croatia on 29 December 2020. This was one of the strongest seismic events that occurred in Croatia in the last two centuries. Field surveys in the epicentral area allowed us to observe and map primary coseismic effects, including geometry and kinematics of surface faulting, as well as secondary effects, such as liquefaction, sinkholes and landslides. The resulting dataset consists of homogeneous georeferenced records identifying 222 observation points, each of which contains a minimum of 5 to a maximum of 14 numeric and string fields of relevant information. The earthquake caused surface faulting defining a typical ‘conjugate’ fault pattern characterized by Y and X shears, tension cracks (T fractures), and compression structures (P shears) within a ca. 10 km wide (across strike), NW–SE striking right-lateral strike-slip shear zone (i.e., the Petrinja Fault Zone, PFZ). We believe that the results of the field survey provide fundamental information to improve the interpretation of seismological, GPS and InSAR data of this earthquake. Moreover, the data related to the surface faulting may impact future studies focused on earthquake processes in active strike-slip settings, integrating the estimates of slip amount and distribution in assessing the hazard associated with capable transcurrent faults.

scholarly journals Analysis of the Impact of Fault Mechanism Radiation Patterns on Macroseismic Fields in the Epicentral Area of 1998 and 2004 Krn Mountains Earthquakes (NW Slovenia)

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Andrej Gosar
Keyword(s):  
Site Effects ◽  
Strike Slip ◽  
Radiation Patterns ◽  
Seismogenic Fault ◽  
Active Growth ◽  
Epicentral Area ◽  
Slip Mechanism ◽  
Radiation Amplitude ◽  
The Difference ◽  
The Impact

Two moderate magnitude (Mw = 5.6 and 5.2) earthquakes in Krn Mountains occurred in 1998 and 2004 which had maximum intensity VII-VIII and VI-VII EMS-98, respectively. Comparison of both macroseismic fields showed unexpected differences in the epicentral area which cannot be explained by site effects. Considerably, different distribution of the highest intensities can be noticed with respect to the strike of the seismogenic fault and in some localities even higher intensities have been estimated for the smaller earthquake. Although hypocentres of both earthquakes were only 2 km apart and were located on the same seismogenic Ravne fault, their focal mechanisms showed a slight difference: almost pure dextral strike-slip for the first event and a strike-slip with small reverse component on a steep fault plane for the second one. Seismotectonically the difference is explained as an active growth of the Ravne fault at its NW end. The radiation patterns of both events were studied to explain their possible impact on the observed variations in macroseismic fields and damage distribution. Radiation amplitude lobes were computed for three orthogonal directions: radial P, SV, and SH. The highest intensities of both earthquakes were systematically observed in directions of four (1998) or two (2004) large amplitude lobes in SH component (which corresponds mainly to Love waves), which have significantly different orientation for both events. On the other hand, radial P direction, which is almost purely symmetrical for the strike-slip mechanism of 1998 event, showed for the 2004 event that its small reverse component of movement has resulted in a very pronounced amplitude lobe in SW direction where two settlements are located which expressed higher intensities in the case of the 2004 event with respect to the 1998 one. Although both macroseismic fields are very complex due to influences of multiple earthquakes, retrofitting activity after 1998, site effects, and sparse distribution of settlements, unusual differences in observed intensities can be explained with different radiation patterns.

New Evidence of the Dextral Strike-Slip Movement in the Liaohe Basin, China: Results from Sem Experiments

2001 ◽  
Vol 44 (6) ◽  
pp. 779-784
Author(s):  
Jia-Zeng SHAN ◽  
Hong-Jun SUN ◽  
Qian-Hua XIAO ◽  
Dao-Jing WANG ◽  
Kun XU ◽  
...  
Keyword(s):  
Strike Slip ◽  
Liaohe Basin ◽  
New Evidence ◽  
Dextral Strike Slip ◽  
Strike Slip Movement

scholarly journals Technologies and new approaches used by the INGV EMERGEO Working Group for real-time data sourcing and processing during the Emilia Romagna (northern Italy) 2012 earthquake sequence

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Giuliana Alessio ◽  
Laura Alfonsi ◽  
Carlo Alberto Brunori ◽  
Pierfrancesco Burrato ◽  
Giuseppe Casula ◽  
...  
Keyword(s):  
Seismic Event ◽  
Main Shock ◽  
Northern Italy ◽  
Earthquake Activity ◽  
Seismic Sequence ◽  
Time Data ◽  
Broad Area ◽  
Epicentral Area ◽  
Po Plain ◽  
Real Time Data

<p>On May 20, 2012, a Ml 5.9 seismic event hit the Emilia Po Plain, triggering intense earthquake activity along a broad area of the Po Plain across the provinces of Modena, Ferrara, Rovigo and Mantova (Figure 1). Nine days later, on May 29, 2012, a Ml 5.8 event occurred roughly 10 km to the SW of the first main shock. These events caused widespread damage and resulted in 26 victims. The aftershock area extended over more than 50 km and was elongated in the WNW-ESE direction, and it included five major aftershocks with 5.1 ≤Ml ≤5.3, and more than 2000 minor events (Figure 1). In general, the seismic sequence was confined to the upper 10 km of the crust. Minor seismicity with depths ranging from 10 km to 30 km extended towards the southern sector of the epicentral area (ISIDe, http://iside.rm.ingv.it/). […]</p><br />

Aftershocks and surface faulting associated with the intraplate Guinea, West Africa, earthquake of 22 December 1983

1987 ◽  
Vol 77 (5) ◽  
pp. 1579-1601
Author(s):  
C. J. Langer ◽  
M. G. Bonilla ◽  
G. A. Bollinger
Keyword(s):  
West Africa ◽  
Focal Mechanism ◽  
Main Shock ◽  
Strike Slip ◽  
Fault System ◽  
Epicentral Area ◽  
Lateral Strike Slip ◽  
Focal Mechanism Solutions ◽  
Short Period ◽  
East West

Abstract This study reports on the results of geological and seismological field studies conducted following the rare occurrence of a moderate-sized West African earthquake (mb = 6.4) with associated ground breakage. The epicentral area of the northwestern Guinea earthquake of 22 December 1983 is a coastal margin, intraplate locale with a very low level of historical seismicity. The principal results include the observation that seismic faulting occurred on a preexisting fault system and that there is good agreement among the surface faulting, the spatial distribution of the aftershock hypocenters, and the composite focal mechanism solutions. We are not able, however, to shed any light on the reason(s) for the unexpected occurrence of this intraplate earthquake. Thus, the significance of this study is its contribution to the observational datum for such earthquakes and for the seismicity of West Africa. The main shock was associated with at least 9 km of surface fault-rupture. Trending east-southeast to east-west, measured fault displacements up to ∼13 cm were predominantly right-lateral strike slip and were accompanied by an additional component (5 to 7 cm) of vertical movement, southwest side down. The surface faulting occurred on a preexisting fault whose field characteristics suggest a low slip rate with very infrequent earthquakes. There were extensive rockfalls and minor liquefaction effects at distances less than 10 km from the surface faulting and main shock epicenter. Main shock focal mechanism solutions derived from teleseismic data by other workers show a strong component of normal faulting motion that was not observed in the ground ruptures. A 15-day period of aftershock monitoring, commencing 22 days after the main shock, was conducted. Eleven portable, analog short-period vertical seismographs were deployed in a network with an aperture of 25 km and an average station spacing of 7 km. Ninety-five aftershocks were located from the more than 200 recorded events with duration magnitudes of about 1.5 or greater. Analysis of a selected subset (91) of those events define a tabular aftershock volume (26 km long by 14 km wide by 4 km thick) trending east-southeast and dipping steeply (∼60°) to the south-southwest. Composite focal mechanisms for groups of events, distributed throughout the aftershock volume, exhibit right-lateral, strike-slip motion on subvertical planes that strike almost due east. Although the general agreement between the field geologic and seismologic results is good, our preferred interpretation is for three en-echelon faults striking almost due east-west.

Coseismic surface "conjugate" faulting of the 29 December 2020., MW 6.4, Petrinja earthquake (Sisak-Moslavina, Croatia)

2021 ◽  
Author(s):  
Emanuele Tondi ◽  
Anna Maria Blumetti
Keyword(s):  
Fault Zone ◽  
Relevant Information ◽  
Strike Slip ◽  
Secondary Effects ◽  
Epicentral Area ◽  
Field Surveys ◽  
Fundamental Information ◽  
Tension Cracks ◽  
Transcurrent Faults ◽  
Geometry And Kinematics

&lt;p&gt;We provide here a first-hand description of the coseismic surface effects caused by the Mw 6.4 Petrinja earthquake that hit central Croatia on 29 December 2020. This was one of the strongest seismic events that occurred in Croatia in the last two centuries. Field surveys in the epicentral area allowed us to observe and map primary coseismic effects, including geometry and kinematics of surface faulting, as well as secondary effects, such as liquefaction, sinkholes and landslides. The resulting dataset consists of homogeneous georeferenced records identifying 222 observation points, each of which contains a minimum of 5 to a maximum of 14 numeric and string fields of relevant information. The earthquake caused surface faulting defining a typical &amp;#8216;conjugate&amp;#8217; fault pattern characterized by Y and X shears, tension cracks (T fractures), and compression structures (P shears) within a ca. 10 km wide, right-lateral strike-slip fault zone (i.e. the Petrinja Fault Zone, PFZ). We believe that the results of the field survey provide fundamental information to improve the interpretation of seismological, GPS and InSAR data of this earthquake. Moreover, the data related to the surface faulting may impact future studies focused on earthquake processes in active strike-slip settings, integrating the estimates of slip amount and distribution in assessing the hazard associated with capable transcurrent faults.&lt;/p&gt;

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