scholarly journals THE SEPTEMBER 2, 2015, КR=14.0, Mw=5.1, I0=7–8 TALLAY EARTHQUAKE at the NORTH-EASTERN FLANK of the BAIKAL RIFT

2021 ◽  
pp. 305-313
Author(s):  
V. Melnikova ◽  
N. Gileva ◽  
Ya. Radziminovich ◽  
A. Filippova
Keyword(s):  
Seismic Event ◽  
Ground Motions ◽  
Moment Tensor ◽  
Seismic Moment Tensor ◽  
Macroseismic Data ◽  
Eastern Flank ◽  
The North ◽  
North Eastern ◽  
Amplitude Spectra ◽  
Strong Ground

We consider September 2, 2015, Mw=5.1 Tallay earthquake occurred in the previously aseismic area of the North-Muya Ridge adjoining to the Muya-Kuanda basin from the north. Instrumental and macroseismic data on this seismic event are presented. Its seismic moment tensor is calculated from surface wave amplitude spectra. New data on strong ground motions are obtained within the north-eastern flank of the Baikal rift. The Tallay earthquake is found to be connected with seismogenic renewal of the second-order multidirectional faults activated in the rift stress field.

scholarly journals BOGUCHAN EARTHQUAKE on JANUARY 17, 2014 with КР=13.3, Mw=4.3, I0=7 (Siberian Platform)

2020 ◽  
pp. 278-287
Author(s):  
A. Seredkina ◽  
V. Melnikova ◽  
N. Gileva ◽  
Ya Radziminovich
Keyword(s):  
Siberian Platform ◽  
Seismic Event ◽  
Deep Structure ◽  
Moment Tensor ◽  
Source Area ◽  
Tectonic Stress ◽  
Seismic Moment Tensor ◽  
Macroseismic Data ◽  
Amplitude Spectra ◽  
Tectonic Features

We consider the Boguchan January 17, 2014 earthquake(Mw=4.3) occurred on the Siberian Platform in the area of the sublongitudinal part of the Angara River. Instrumental and macroseismic data on this seismic event, tectonic features and deep structure of the crust within its source area are analyzed. Seismic moment tensor and hypocentral depth of the earthquake are calculated from its surface wave amplitude spectra. It has been shown that the concentration and relaxation of the tectonic stress in the source area are likely to be conditioned by velocity heterogeneities in the upper and middle crust. The obtained facts evidence that the study earthquake, most probably, is not connected with filling of the Angara cascade of water reservoirs.

scholarly journals STRONG EARTHQUAKES in the NORTH of the LAKE BAIKAL REGION (Mw=4.6–4.7) in 2015

2021 ◽  
pp. 276-290
Author(s):  
Ya. Radziminovich ◽  
V. Melnikova ◽  
N. Gileva ◽  
A. Filippova
Keyword(s):  
Lake Baikal ◽  
Baikal Region ◽  
Moment Tensor ◽  
Seismic Hazard Assessment ◽  
Normal Fault ◽  
Seismic Moment Tensor ◽  
Macroseismic Data ◽  
Strong Earthquakes ◽  
The North ◽  
Lake Baikal Region

The paper considers three relatively strong earthquakes that occurred in 2015 in the northern Lake Baikal region: July 7 Upper Akuli earthquake (Mw=4.6) with the epicenter at the headwaters of the Akuli River, and September 25 Gulonga-I (Mw=4.7) and December 13 Gulonga-II earthquakes (Mw=4.6) with the epicenters near the mountain lakes Gulonga. Instrumental and macroseismic data on these seismic events are reported. A seismic moment tensor, calculated from surface wave records, shows normal fault focal mechanisms for Upper Akuli and Gulonga-II earthquakes and strike-slip movements in the source of the Gulonga-I seismic event. The results obtained could be used in further studies of seismic zoning and seismic hazard assessment in the northern Lake Baikal region.

Seismology and Strong Ground Motions in the 2004 Niigata Ken Chuetsu, Japan, Earthquake

2006 ◽  
Vol 22 (1_suppl) ◽  
pp. 9-21 ◽  
Author(s):  
Jim Mori ◽  
Paul Somerville
Keyword(s):  
Main Shock ◽  
Ground Motions ◽  
Moment Tensor ◽  
Hanging Wall ◽  
Active Faults ◽  
Field Investigation ◽  
Extensive Field ◽  
Reverse Faulting ◽  
Significant Region ◽  
Strong Ground

The Niigata Ken Chuetsu earthquake was a shallow, moderate-sized event producing strong shaking and considerable land failure damage across a significant region of Niigata Prefecture in central Japan. Moment tensor solutions indicate the main shock as being pure reverse faulting on a fault striking 30° east of north, roughly parallel to the mapped active faults and to the structural trends of the region, with nodal planes that dip down to the west at about 50° and down to the east at about 40°. The main shock was followed by an unusual number of large aftershocks. An extensive field investigation identified only minor surface faulting. Hanging wall effects accompanied by unusually high accelerations were observed, with peak horizontal accelerations of 1.75 g recorded at Tohkamachi and 1.33 g recorded at Ojiya.

scholarly journals The Quaternary Active El Arrayan Fault, Santiago, Chile

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Jose Araya ◽  
Gregory P. De Pascale ◽  
Sergio Sepúlveda
Keyword(s):  
Active Fault ◽  
Ground Motions ◽  
Hanging Wall ◽  
Local Source ◽  
Fault Rupture ◽  
Fault Rocks ◽  
Strong Ground Motions ◽  
The North ◽  
The City ◽  
Strong Ground

Understanding the location and nature of Quaternary active crustal faults is critical to the reduction of both fault rupture and strong ground motions hazards in the built environment. Recent work along the San Ramon Fault in Santiago, Chile demonstrates that crustal seismic sources are important hazards. We present the results of a second likely Quaternary active fault (the El Arrayan Fault, EAF) that runs through the City of Santiago. The EAF was discovered at an outcrop in El Arrayan (Lo Barnechea) with up to the North reverse motion and sinistral (left-lateral) motion clearly visible and coincident with fault rocks (gouge, cataclasite, and breccia) and higher topography (i.e. uplift) in the hanging wall. The EAF is at least 12 km long, strikes North-Northwest to South-Southeast, and is steeply dipping (mean dip 77º NE). Clear geomorphic expression with sinistral displaced streams (up to ~210 m) suggest that this fault is Quaternary active and an important local source of fault rupture and crustal strong ground motions. Because no fault zone avoidance criteria in Chile, there is need for enhanced fault mapping, legislation, implementation of active fault rupture avoidance areas in Chile to reduce the risk posed by active crustal structures.

scholarly journals MUYAKAN EARTHQUAKE SEQUENCE in 2015 (Northern Baikal Region)

2021 ◽  
pp. 245-257
Author(s):  
N. Gileva ◽  
V. Melnikova ◽  
A. Filippova ◽  
Ya. Radziminovich ◽  
E. Kobeleva
Keyword(s):  
Baikal Region ◽  
Seismic Station ◽  
Local Stress ◽  
Baikal Rift Zone ◽  
Focal Mechanisms ◽  
Macroseismic Data ◽  
The North ◽  
Macroseismic Effects ◽  
North Eastern ◽  
Spatio Temporal

We present the results of studies of the seismic regime, focal mechanisms, and macroseismic data in the area of the largest Muyakan activation in 2015 (northern Baikal region). Due to the deployment of a network of temporary seismic stations, the number of registered earthquakes (KR≥3) increased significantly in 2015 and reached  30 thousand. Spatio-temporal development of the considered activation is characterized by stable low values of earthquake hypocenters and dividing the epicentral field into two clusters – eastern and north-western ones. Both clusters are connected with local stress-strain field (rift type and strike-slip, respectively), while the general regime of seismotectonic deformations of the crust in the activation area, calculated from the statistical analysis of 77 focal mechanisms of Muyakan earthquakes (KR≥9.2), demonstrates the predominance of submeri-dional horizontal extension. Macroseismic effects from the largest earthquakes of the Muyakan sequence were felt, predominantly, in Severomuysk settlement (=10–15 km, I=5). New data on strong motions, obtained from the records of the seismic station with the same name, have significantly complemented the database for the territory of the north-eastern flank of the Baikal rift zone. In general, the obtained results could be used to clarify the seismic hazard of the considered area and to improve the instrumental part of seismic scales.

scholarly journals MUYAKAN-II EARTHQUAKE on MAY 23, 2014 with КР=14.3, Mw=5.5, I0=7–8 (Northern Baikal region)

2020 ◽  
pp. 323-333
Author(s):  
N. Gileva ◽  
V. Melnikova ◽  
A. Seredkina ◽  
Ya. Radziminovich
Keyword(s):  
Seismic Moment ◽  
Main Shock ◽  
Moment Tensor ◽  
Seismic Hazard Assessment ◽  
Baikal Rift Zone ◽  
Temporal Analysis ◽  
Seismic Moment Tensor ◽  
Depth Range ◽  
North East ◽  
The North

We consider the May 23, 2014 Muyakan earthquake (Mw=5.5) occurred in the Muyakan Range at the north-east of the Baikal rift zone near the eastern tunnel portal of the Baikal-Amur Mainline. This event was followed by numerous aftershocks (КР=5.6–9.9) which number exceeded 2000 by the end of the year. Spatio-temporal analysis of the Muyakan seismic sequence shows that its epicentral field consists of two isolated clusters: eastern and western ones. All the main events including the foreshocks, main shock and the strongest aftershocks (Mw=4.4; 4.5) occurred in the eastern cluster while only small seismic events (КР<10.0) were recorded in the western one. Seismic moment tensor was calculated for the Muyakan earthquake from surface wave amplitude spectra. As a result, we obtained information about the rift type focal mechanism, scalar seismic moment (M0=1.9•1017 Nm), moment magnitude (Mw=5.5) and hypocentral depth (h=24 km). From regional data, hypocentral depths of the main shock and the major number of the following earthquakes (80 %) were distributed in the depth range h=3–11 km. Maximum intensity of the main shock (4–5 according to MSK-64) was felt in Severomuysk urban village (=29 km). The obtained results could be used for seismic hazard assessment of the crucial part of the Baikal-Amur Mainline.

scholarly journals Moment tensor inversion of early instrumental data: application to the 1917 High Tiber Valley, Monterchi earthquake

2016 ◽  
Vol 59 (3) ◽  
Author(s):  
Fabrizio Bernardi ◽  
Maria Grazia Ciaccio ◽  
Barbara Palombo ◽  
Graziano Ferrari
Keyword(s):  
Focal Mechanism ◽  
Moment Tensor ◽  
Source Parameters ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Moment Magnitude ◽  
Macroseismic Data ◽  
Natural Period ◽  
Amplitude Spectra ◽  
Tiber Valley

<p>In this paper we present a new study on the High Tiber Valley earthquake occurred on April 26, 1917. Using the digitized data from mechanical seismograph records, we computed the source parameters like focal mechanism and moment magnitude from moment tensor (MT). The study of historical earthquakes from an instrumental perspective is crucial because of the complexity of problems associated with the study of seismograms of moderate to large earthquakes occurred from the late 19th century until the early 1960s. Since historical earthquake records show significant uncertainties in phase arrival times and have been recorded by seismograph generally with short natural period, we developed a code to compute the MT based on a forward modeling technique, which uses the amplitude spectra of the full waveform length and the first P-arrival polarities to constrain the P- and T-axes. The best solution is determined by the best fit between the observed and synthetic amplitude spectra and from the coherency between the observed and the theoretical first P-arrival polarities. The 1917 High Tiber Valley earthquake is one of the most important 20th century earthquake occurred in the Italian Peninsula for which the focal mechanism and moment magnitude from seismic records are not available. Additionally, we apply a multidisciplinary approach to characterize the source of this earthquake, combining instrumental, macroseismic, geological and tectonic data and investigations. The computed MT results in a north-south normal fault mechanism (strike: 147°, dip: 29°, slip: −94°), which is consistent with the strike estimated from the macroseismic data (157°). The moment magnitude calculated from the MT and that derived from the macroseismic data are M<span><sub>w</sub></span>=5.5±0.2 and M<span><sub>w</sub></span>=5.9±0.1, respectively.</p>

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