Microzonation of Earthquake Hazards

Introduction

Many earthquakes in the past have left many lessons to be learned which are very essential to plan infrastructure and even to mitigate such calamities in the future. The hazards associated with earthquakes are referred to as seismic hazards. The practise of earthquake engineering involves the identification and mitigation of seismic hazards. Microzonation has generally been recognized as the most accepted tool in seismic hazard assessment and risk evaluation. It is defined as the zonation concerning ground-motion characteristics taking into account source and site conditions. Making improvements on the conventional macrozonation maps and regional hazard maps, the micro zonation of the ar region generates detailed maps that predict the hazard at much smaller scales. Seismic microzonation is the generic name for subdividing a region into individual areas having different potentials hazardous earthquake effects, defining their specific seismic behaviour for engineering design and land-use planning.

Fundamentals

The basis of microzonation is to model the rupture mechanism at the source of an earthquake, evaluate the propagation of waves through the earth to the top of bedrock, determine the effect of the local soil profile and thus develop a hazard map indicating the vulnerability of the area to potential seismic hazard. Seismic microzonation will also help in designing buried lifelines such as tunnels, water and sewage lines, gas and oil lines, and power and communication lines.
Seismic microzonation is defined as the process of subdividing a potential earthquake-prone area into zones concerning some geological and geophysical characteristics of the sites such as ground shaking, liquefaction susceptibility, landslide and rockfall hazard, earthquake-related flooding so that seismic hazards at different locations within the area can correctly be identified. Microzonation provides the basis for site-specific risk analysis, which can assist in the mitigation of earthquake damage.

Effect of Site Conditions on Earthquake Ground Motion

It has long been recognized that the intensity of ground shaking during earthquakes and the associated damage to structures are significantly influenced by local geologic and soil conditions. Unconsolidated sediments are found to amplify ground motion during earthquakes and are hence more prone to earthquake damage than ground with hard strata. Modern cities built on soft sediments are especially vulnerable to damage caused by amplified ground motions.

Conclusion:

Dynamic characteristics of the site such as predominant period, amplification factor, shear wave velocity, standard penetration test values can be used for seismic microzonation purpose. Microtremor observations are easy to perform, inexpensive and can be applied to places with low seismicity as well; hence, microtremor measurements can be used conveniently for microzonation.In a nutshell, microzonation is the need of the hour to deal with such terrible and devastating disasters.


WRITTEN BY: Biswajit Sahoo and Debasish Beria


Comments

Post a Comment

Popular posts from this blog

The Venice Tide Barrier System - MOSE Project

Image
Introduction: The city Venice located on the east coast of Italy, is a world-famous tourist spot. It was hit by several floods and massive waves from the Adriatic Sea in the past few decades. Many experts claim that the water level in the sea is rising day by day. In 1966, it became a significant concern as the tides rose to an enormous height of more than 7 feet above the seawater level. This project consists of 78 gigantic steel panels across the three inlets that allow water to surge from the Adriatic Sea into the Venice lagoon. The MOSE System: The Venice city lagoon has three main water inlets at Malamocco, Chioggia, and Lido. To protect the city from flooding, the government planned to temporarily close these three water inlets. In 2003, the approval for MOSE, an Italian acronym for Experimental Electromechanical Module, was passed to construct an artificial barrier that would protect the city from any future floods. Its fundamental idea was to engage a series of oscillating infl
Read more

Lasers: A Revolution in Highway Engineerin

Image
Introduction: - The advancement of new technology has been taking place since the beginning of human history. However, it has been exceptionally fast and changing the engineering world in recent decades at a record pace. One such technology, lasers, is used in highway engineering for various purposes like road profiling, pavement surface redirection, bridge deflection, speed checkers, accident spot analysis etc. These laser techniques have greater accuracy as everything is automated with faster data collection and less human involvement. Applications: - Road Profiling The profile of a path is calculated around some in-existent line or point which is permanent. Besides the rutting and the other issues, the profile of a path which is taken along a lateral line shows over the altitude and crown of the route outline. The longitudinal profile displays the ruggedness, hardness, and grade of the material. It is used for tracking the status of a pavement management system road network (PMS) ne
Read more

Placement Talks with Ayush Prasad Kasar

Image
Mr. AYUSH PRASAD KASAR     Thinking is the hardest work there is, which is probably the reason so few engage in it.  ~ Henry Ford     Getting an “on-campus” core job may seem like a “next to impossible” task for many, but it may not be the reality for a true aspiring individual. CEST club in association with ICE UK- NIT Rourkela chapter brings you an encouraging conversation with Mr.  Ayush  (from the batch of 2021) who has been a “near to perfect” example of patience, hard work and dedication.  Due to his perseverance and continuous efforts, he   got placed in  GAIL. His journey may become the blue print for all those who are aiming to be placed on-campus in core engineering companies.       Enlighten us about your life before joining NIT Rourkela.     I was born in  Rajnandgaon  in Chhattisgarh. I did my schooling from Nursery to the fifth standard in Bal  Bharti  Public School. Due to my parent’s continuous effort to help me in my studies from the beginning, I  secured good marks in
Read more