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.

The 23 October 2011 MW7.0 Van (Eastern Turkey) Earthquake: Interpretations of Recorded Strong Ground Motions and Post-Earthquake Conditions of Nearby Structures

2014 ◽  
Vol 30 (2) ◽  
pp. 657-682 ◽  
Author(s):  
V. Akansel ◽  
G. Ameri ◽  
A. Askan ◽  
A. Caner ◽  
B. Erdil ◽  
...  
Keyword(s):  
Fault Plane ◽  
Ground Motions ◽  
Hanging Wall ◽  
Strong Motion ◽  
Thrust Fault ◽  
Building Structures ◽  
Epicentral Area ◽  
Historical Structures ◽  
Strict Compliance ◽  
Strong Ground

A major thrust-fault earthquake of MW = 7.0 occurred on 23 October 2011 at 10:41:21 UTC in the eastern Anatolian region of Turkey, severely affecting the nearby towns of Van and Erciş. In this study, a few strong-motion records from the epicentral area are analyzed in order to investigate the characteristics of the ground motions. Also reported are the post-earthquake field observations for various types of structures, such as buildings, bridges, historical structures, tunnels, and dams within the vicinity of the fault plane. The spatial distribution of damage indicates a noticeable hanging-wall effect. The special-type structures are observed to experience far less damage, as opposed to the building structures in the region pointing to the need for strict compliance to seismic building code and the corresponding construction requirements.

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 Clusty, the waveform-based network similarity clustering toolbox: concept and application to image complex faulting offshore Zakynthos (Greece)

2020 ◽  
Vol 224 (3) ◽  
pp. 2044-2059
Author(s):  
G M Petersen ◽  
P Niemz ◽  
S Cesca ◽  
V Mouslopoulou ◽  
G M Bocchini
Keyword(s):  
Main Shock ◽  
Moment Tensor ◽  
Tectonic Setting ◽  
Active Faults ◽  
Aftershock Sequence ◽  
Strike Slip ◽  
Large Magnitude ◽  
Data Set ◽  
Network Similarity ◽  
Waveform Similarity

SUMMARY Clusty is a new open source toolbox dedicated to earthquake clustering based on waveforms recorded across a network of seismic stations. Its main application is the study of active faults and the detection and characterization of faults and fault networks. By using a density-based clustering approach, earthquakes pertaining to a common fault can be recognized even over long fault segments, and the first-order geometry and extent of active faults can be inferred. Clusty implements multiple techniques to compute a waveform based network similarity from maximum cross-correlation coefficients at multiple stations. The clustering procedure is designed to be transparent and parameters can be easily tuned. It is supported by a number of analysis visualization tools which help to assess the homogeneity within each cluster and the differences among distinct clusters. The toolbox returns graphical representations of the results. A list of representative events and stacked waveforms facilitate further analyses like moment tensor inversion. Results obtained in various frequency bands can be combined to account for large magnitude ranges. Thanks to the simple configuration, the toolbox is easily adaptable to new data sets and to large magnitude ranges. To show the potential of our new toolbox, we apply Clusty to the aftershock sequence of the Mw 6.9 25 October 2018 Zakynthos (Greece) Earthquake. Thanks to the complex tectonic setting at the western termination of the Hellenic Subduction System where multiple faults and faulting styles operate simultaneously, the Zakynthos data set provides an ideal case-study for our clustering analysis toolbox. Our results support the activation of several faults and provide insight into the geometry of faults or fault segments. We identify two large thrust faulting clusters in the vicinity of the main shock and multiple strike-slip clusters to the east, west and south of these clusters. Despite its location within the largest thrust cluster, the main shock does not show a high waveform similarity to any of the clusters. This is consistent with the results of other studies suggesting a complex failure mechanism for the main shock. We propose the existence of conjugated strike-slip faults in the south of the study area. Our waveform similarity based clustering toolbox is able to reveal distinct event clusters which cannot be discriminated based on locations and/or timing only. Additionally, the clustering results allows distinction between fault and auxiliary planes of focal mechanisms and to associate them to known active faults.

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 Broadband Strong-Motion Prediction for Future Nankai-Trough Earthquakes Using Statistical Green’s Function Method and Subsequent Building Damage Evaluation

2021 ◽  
Vol 11 (15) ◽  
pp. 7041
Author(s):  
Baoyintu Baoyintu ◽  
Naren Mandula ◽  
Hiroshi Kawase
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Nankai Trough ◽  
Ground Motions ◽  
Building Damage ◽  
Steel Buildings ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Strong Ground Motions ◽  
Strong Ground

We used the Green’s function summation method together with the randomly perturbed asperity sources to sum up broadband statistical Green’s functions of a moderate-size source and predict strong ground motions due to the expected M8.1 to 8.7 Nankai-Trough earthquakes along the southern coast of western Japan. We successfully simulated seismic intensity distributions similar to the past earthquakes and strong ground motions similar to the empirical attenuation relations of peak ground acceleration and velocity. Using these results, we predicted building damage by non-linear response analyses and find that at the regions close to the source, as well as regions with relatively thick, soft sediments such as the shoreline and alluvium valleys along the rivers, there is a possibility of severe damage regardless of the types of buildings. Moreover, the predicted damage ratios for buildings built before 1981 are much higher than those built after because of the significant code modifications in 1981. We also find that the damage ratio is highest for steel buildings, followed by wooden houses, and then reinforced concrete buildings.

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