What is seismic hazard analysis?
Based on geological and seismological studies, probabilistic seismic hazard analysis (PSHA) estimates the likelihood of a hazard, considering the uncertainties in magnitude and the location of earthquakes and their resulting ground motions that are likely to affect a particular site.
What are the four types of earthquake hazards?
Primary earthquake hazards are:
- ground shaking.
- surface rupture.
Why do we do seismic hazard analysis?
It is an accepted trend in engineering practice to develop design response spectrum for different types of foundation materials such as rock, hard soil and weak soils. Analysis of lineaments and faults helps in understanding the regional seismotectonic activity of the area.
How do you manage seismic hazards?
We cannot prevent natural earthquakes from occurring but we can significantly mitigate their effects by identifying hazards, building safer structures, and providing education on earthquake safety. By preparing for natural earthquakes we can also reduce the risk from human induced earthquakes.
How is seismic risk calculated?
A simplified method of calculating seismic risk for a given city, involves the use of a street survey. If you know the level of seismic hazard, the damage generally follows established patterns.
What are the 5 earthquake related hazards?
Earthquake hazard is anything associated with an earthquake that may affect the normal activities of people. This includes surface faulting, ground shaking, landslide, liquefaction, tectonic deformation, tsunamis, and seiches.
What are the major geotechnical seismic hazards?
the principal geotechnical hazards associated with earthquakes are: 1 fault rupture 2 ground shaking 3 liquefaction and lateral spreading 4 landslides and rockfalls 5 tsunami. Each of these hazards is described in more detail below.
What is structural and nonstructural mitigation?
Non-structural mitigation differs most significantly from that of structural mitigation in that it reduces risk (likelihood and consequences) without requiring the use of engineered structures. Nonstructural mitigation techniques are often considered mechanisms where “man adapts to nature.”
How does building design reduce the impact of earthquakes?
Base isolation involves constructing a building on top of flexible pads made of steel, rubber, and lead. When the base moves during the earthquake, the isolators vibrate while the structure itself remains steady. This effectively helps to absorb seismic waves and prevent them from traveling through a building.
What are the two basic approaches to seismic hazard analysis?
There are two basic approaches to seismic hazard analysis. Both use the same basic body of information to determine what the “design earthquake” should be. The main difference is that the probabilistic approach systematically examines the uncertainties and includes the likelihood of an actual earthquake exceeding the design ground motion.
How do seismic hazard maps work for soft soil?
All of the previous developments (e.g., seismic hazard maps) were for sites on very firm soil. For sites on softer soil, the ground motions will be amplified. This slide shows ground motion occurring in rock (lower time history) and in a softer material such as a clay.
What is seseismic hazard analysis?
SEISMIC HAZARD ANALYSIS This topic addresses deterministic and probabilistic seismic hazard analysis, ground motion attenuation relationships, the U.S. Geological Survey (USGS) seismic hazard maps, the NEHRP Recommended Provisionsseismic design maps, site effects, directionality effects, and the NEHRP Recommended Provisionsresponse spectrum.
How is USGS earthquake hazard information applied in seismic design practice?
The design code developers first decide how USGS earthquake hazard information should be applied in design practice. Then, the USGS calculates values of seismic design parameters based on USGS hazard values and in accordance with design code procedures.