Seismic Microzonation and Site Effects Detection Through Microtremors Measures

2018 ◽  
pp. 326-349
Author(s):  
Francisco Alberto Calderon ◽  
Emilce Gisela Giolo ◽  
Carlos Daniel Frau ◽  
Marcelo Gerardo Jesús Guevara Rengel ◽  
Hernan Rodriguez ◽  
...  
Keyword(s):  
Site Effects ◽  
Amplification Factor ◽  
Seismic Microzonation ◽  
Poor Countries ◽  
Advantages And Disadvantages ◽  
Cheap Method ◽  
Hvsr Method ◽  
Seismic Amplification ◽  
Fundamental Reason ◽  
Well Correlation

Seismic microzonation of a city can be a difficult and expensive undertaking depending on the method used. In the last years, the HVSR method has been one of the most popular ways to define the natural frequency of the soil and seismic amplification factor in order to make quick microzonations due to that it is an expeditious and cheap method. This is very important in developing countries and poor countries. The fundamental reason to use this method is the fact that the amplification factor has well correlation with damage distribution. Additionally with the help of another methods it is possible obtain the structure of the superficial soil strata. In this chapter, an introduction with seismic microzonation, site effects concepts, microtremors, description of the HVSR method, advantages and disadvantages of this method, limitations and comparison with other methods, are presented. Finally, highlight of the importance of the method in order to identify site effects are displayed as examples and the incorporation of these data to Geographic Information Systems is also shown.

scholarly journals MzS Tools: GIS Methods and Tools for Seismic Microzonation Mapping

2021 ◽  
Author(s):  
Giuseppe Cosentino ◽  
Francesco Pennica ◽  
Emanuele Tarquini ◽  
Giuseppe Cavuoto ◽  
Francesco Stigliano
Keyword(s):  
Amplification Factor ◽  
Data Entry ◽  
National Research Council ◽  
Seismic Microzonation ◽  
Database Management System ◽  
Structural Elements ◽  
Software Environment ◽  
Seismic Amplification ◽  
Gis Methods ◽  
Relational Database Management

MzSTools is a plugin for QGIS developed by the National Research Council (CNR) as part of the activities concerning the coordination of seismic microzonation studies in Italy. It train from the need to create a practical and easy-to-use tool to carry out seismic microzonation (SM) studies by producing standards compliant geographic database and maps, thus making them accurate, homogeneous and uniform for all municipalities in Italy. A geodatabase based on SQLite/SpatiaLite Relational Database Management System (RDBMS). It has been designed to collect and store data related to elements such as: geognostic surveys; bedrocks and cover terrains; superficial and buried geomorphological elements; tectonic-structural elements; elements of geological instability such as landslide zones, liquefaction zones and zones affected by active and capable faults; homogeneous microzones in seismic perspective, microzones characterized by a seismic amplification factor. The QGIS plugin provides tools such as data entry forms designed with Qt Designer; a QGIS project template with layers, symbol libraries and graphic styles; layouts for the SM Maps. MzSTools assembles in a single software environment a set of useful tools for those who work in. The plugin is open source, whose code hosted on the GitHub platform, and is published via the official QGIS plugins repository (https://plugins.qgis.org/plugins/MzSTools/).

SEISMIC MICROZONATION AND SITE EFFECTS AT AL HOCEIMA CITY, MOROCCO

2004 ◽  
Vol 8 (4) ◽  
pp. 585-596 ◽  
Author(s):  
ABDELOUAHID TALHAOUI ◽  
AOMAR IBEN BRAHIM ◽  
M'HAMED ABERKAN ◽  
MOHAMED KASMI ◽  
AZELARAB EL MOURAOUAH
Keyword(s):  
Site Effects ◽  
Seismic Microzonation ◽  
Al Hoceima

scholarly journals Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

2017 ◽  
Vol 17 (6) ◽  
pp. 925-937 ◽  
Author(s):  
Andrej Gosar
Keyword(s):  
Seismic Hazard ◽  
Resonance Frequency ◽  
Complex Geometry ◽  
Free Field ◽  
Seismic Microzonation ◽  
Clear Correlation ◽  
S Wave ◽  
Resonance Frequencies ◽  
Hvsr Method ◽  
The Town

Abstract. The town of Idrija is located in an area with an increased seismic hazard in W Slovenia and is partly built on alluvial sediments or artificial mining and smelting deposits which can amplify seismic ground motion. There is a need to prepare a comprehensive seismic microzonation in the near future to support seismic hazard and risk assessment. To study the applicability of the microtremor horizontal-to-vertical spectral ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in a town area of 0.8 km2 with 50–200 m spacing between the points. The HVSR analysis has shown that it is possible to derive the sediments' resonance frequency at 48 points. With the remaining one third of the measurements, nearly flat HVSR curves were obtained, indicating a small or negligible impedance contrast with the seismological bedrock. The isofrequency (a range of 2.5–19.5 Hz) and the HVSR peak amplitude (a range of 3–6, with a few larger values) maps were prepared using the natural neighbor interpolation algorithm and compared with the geological map and the map of artificial deposits. Surprisingly no clear correlation was found between the distribution of resonance frequencies or peak amplitudes and the known extent of the supposed soft sediments or deposits. This can be explained by relatively well-compacted and rather stiff deposits and the complex geometry of sedimentary bodies. However, at several individual locations it was possible to correlate the shape and amplitude of the HVSR curve with the known geological structure and prominent site effects were established in different places. In given conditions (very limited free space and a high level of noise) it would be difficult to perform an active seismic refraction or MASW measurements to investigate the S-wave velocity profiles and the thickness of sediments in detail, which would be representative enough for microzonation purposes. The importance of the microtremor method is therefore even greater, because it enables a direct estimation of the resonance frequency without knowing the internal structure and physical properties of the shallow subsurface. The results of this study can be directly used in analyses of the possible occurrence of soil–structure resonance of individual buildings, including important cultural heritage mining and other structures protected by UNESCO. Another application of the derived free-field isofrequency map is to support soil classification according to the recent trends in building codes and to calibrate Vs profiles obtained from the microtremor array or geophysical measurements.

scholarly journals Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects

2018 ◽  
Vol 7 (9) ◽  
pp. 375 ◽  
Author(s):  
Han-Saem Kim ◽  
Chang-Guk Sun ◽  
Hyung-Ik Cho
Keyword(s):  
Site Effects ◽  
Focal Depth ◽  
Earthquake Hazard ◽  
Earthquake Damage ◽  
Site Classification ◽  
Topographical Effects ◽  
Seismic Site Effects ◽  
Moderate Earthquake ◽  
Seismic Amplification ◽  
Earthquake Moment

The 2017 Pohang earthquake (moment magnitude scale: 5.4) was South Korea’s second strongest earthquake in decades, and caused the maximum amount of damage in terms of infrastructure and human injuries. As the epicenters were located in regions with Quaternary sediments, which involve distributions of thick fill and alluvial geo-layers, the induced damages were more severe owing to seismic amplification and liquefaction. Thus, to identify the influence of site-specific seismic effects, a post-earthquake survey framework for rapid earthquake damage estimation, correlated with seismic site effects, was proposed and applied in the region of the Pohang earthquake epicenter. Seismic zones were determined on the basis of ground motion by classifying sites using the multivariate site classification system. Low-rise structures with slight and moderate earthquake damage were noted to be concentrated in softer sites owing to the low focal depth of the site, topographical effects, and high frequency range of the mainshocks.

scholarly journals Analisis Shear Strain dan Kerusakan Bangunan Akibat Gempa Bumi di Kecamatan Gading Cempaka dan Ratu Agung Kota Bengkulu

2018 ◽  
Vol 2 (2) ◽  
pp. 222-226
Author(s):  
Kurnia Lestari ◽  
Muchammad Farid ◽  
Afrizal Mayub
Keyword(s):  
Shear Strain ◽  
Land Surface ◽  
Amplification Factor ◽  
Dominant Frequency ◽  
Building Damage ◽  
Entire Area ◽  
Hvsr Method ◽  
Geological Formation ◽  
Formation Type ◽  
The Relationship

ABSTRACT  [The Analysis of Shear Strain and Building Damage due to Earthquake at Gading Cempaka and Ratu Agung District in Bengkulu City]. The aims of this research are to: (1) determine and mapping the distribution of shear strain values, (2) correlate between shear strains with building damage Gading Cempaka and Ratu Agung caused by earthwuake at sub district in Bengkulu city. Microtremor data were taken at 108 observation points then analyzed using HVSR method to obtain amplification factor and dominant frequency values..The result showed that shear strain value of Gading Cempaka and Ratu Agung sub district in Bengkulu city are relatively heterogeneous although in the same geological formation type. The earthquake in 2007 is estimated to be 3.38% potential to deform the land surface in the form of fractures and settlements and 96, 62% potentially experience shocks due to waves and vibrations due to earthquake. The earthquake of 2000 estimated that almost the entire area of Gading Cempaka and Ratu Agung has the potential to experience shocks due to waves and vibrations due to earthquake that is equal to 97% while potentially liquefaction (ambles) occurs by 3%. The correlation between shear strain with the damage of buildings due to earthquake shows the relationship is directly proportional to the function y = 15267x + 26.219 with the coefficient of resgression of    = 0.671. Keywords:  Earthquake;  HVSR method;  microtremor;  shear strain.

Assessment of seismic amplification factor of excavation with support system

2019 ◽  
Vol 18 (3) ◽  
pp. 555-566 ◽  
Author(s):  
Hamidreza Tavakoli ◽  
Saman Soleimani Kutanaei ◽  
Seyed Hossein Hosseini
Keyword(s):  
Support System ◽  
Amplification Factor ◽  
Seismic Amplification

scholarly journals The slope seismic response monitoring of Wenchuan aftershocks in Qingchuan

2014 ◽  
Vol 2 (6) ◽  
pp. 4135-4161
Author(s):  
Y. H. Luo ◽  
R. Huang ◽  
Y. Wang
Keyword(s):  
Seismic Response ◽  
Amplification Factor ◽  
Epicentral Distance ◽  
Spectral Ratio ◽  
Response Monitoring ◽  
Sufficient Evidence ◽  
2008 Wenchuan Earthquake ◽  
Amplification Effect ◽  
Acceleration Amplification ◽  
Seismic Amplification

Abstract. This work reports some new progress of rock slope inside seismic response monitoring results in the area of Mountain Dong and Mountain Shizi (Qingchuan county), located more than 250 km NE of Yingxiu epicenter (2008 Wenchuan earthquake), Sichuan province. Five adits with the maximum depth of 15 m had been excavated in different elevation on both sides slope. Stations were emplaced at middle of the adits, from September 2009 to May 2010 more than 60 Wenchuan aftershocks had been monitored, 22 typical aftershocks had been analysis, whose magnitude varied between 2.3 ~ 5.2 and epicentral distance was from a few to 45 km. A comparison analysis of recordings provided evidence of the presence amplification effect at the Q4 station of Mt. Dong, which the peak horizontal acceleration amplification factor is between 1.0 ~ 2.5. But this amplification effect had no stronger at other stations. Comprehensive studies show that the relative height to riverbed is an important factor of Q4 seismic amplification effect. Otherwise the topography of Q4 site is conducive to horizontal amplification, not the vertical amplification. Moreover the calculation of Arias intensity (Ia) had the same amplification effect as the PGA, only the amplification factor is between 1.0 ~ 3.47 much bigger than the latter. On the other hand, the calculation of horizontal to vertical spectral ratio (HVSR) at Q4 shows the curves have multiple peaks corresponding with different dominant frequencies, which the amplification factor is always bigger than other stations at Mt. Dong. Sufficient evidence indicates that the Mt. Dong amplification effect is stronger than Mt. Shizi.

scholarly journals Microzonation of Cisarua District Using Horizontal Vertical Spectral Ratio

2021 ◽  
Vol 5 (2) ◽  
pp. 88-94
Author(s):  
Elrangga Ibrahim Fattah ◽  
Keyword(s):  
Amplification Factor ◽  
Active Faults ◽  
Spectral Ratio ◽  
Dominant Frequency ◽  
Research Area ◽  
Geological Structure ◽  
Eurasian Plate ◽  
Hvsr Method ◽  
Microtremor Measurement ◽  
Tectonic System

The Bandung region is part of the framework of the Indonesian tectonic system, namely the tectonic plate meeting zone, where the Indo Autralia plate is infiltrated under the Eurasian plate in a convergent manner. The subduction process produces an effect in the form of an active fault geological structure in the Bandung area. One of these active faults is the Lembang Fault, which has a length of ± 29 kilometers and a shear acceleration of 3 to 5.5 millimeters per year. The microtremor measurement method is a passive geophysical method that utilizes natural subsurface vibrations so that it can provide dominant frequency data and amplification factors for soil layers. Based on the results of seismic susceptibility research using microtremor measurements using the HVSR method in the Lembang Fault zone in Cisarua Sub-District, it can be seen that the distribution of the dominant frequency values tends to be influenced by lithology and topography. In the research area, it is known to have a dominant frequency value that varies due to the different types of lithological units. In general, the dominant frequency ranges from 1-3 Hz because it is dominated by tuff sand and tuff pumice, and areas composed of volcanic breccias have a dominant frequency value between 3-6 Hz. Meanwhile, the amplification factor value will be influenced by rock deformation and weathering. The area that has a very high amplification factor value is in the southeast of the study area with an A0 value greater than 5. This indicates that the area is composed of a layer of thick and not dense tuff sand

Sign in / Sign up

Export Citation Format

Share Document