Động đất xảy ra hằng ngày trên trái đất, nhưng hầu hết không đáng chú ý và không gây ra thiệt hại. Động đất lớn có thể gây thiệt hại trầm trọng và gây tử vong bằng nhiều cách. Động đất có thể gây ra đất lở, đất nứt, sóng thần, nước triều giả, đê vỡ, và hỏa hoạn. | 22 Basic Geotechnical Earthquake Engineering a left-lateral fault. The way to keep these terms straight is to imagine that we are standing on one side of the fault and an earthquake occurs. If objects on the other side of the fault move to our left it s a left-lateral fault if they move to our right it s a right-lateral fault. When the hanging wall motion is neither dominantly vertical nor horizontal the motion is called oblique-slip. Although oblique faulting isn t unusual it is less common than the normal reverse and strike-slip movement. Fig. explains about different fault classifications. Left-lateral Right-lateral Oblique Fig. Different fault classifications Courtesy http Normal faulting is indicative of a region that is stretching and on the continents normal faulting usually occurs in regions with relatively high elevation such as plateaus. Reverse faulting reflects compressive forces squeezing a region and they are common in uplifting mountain ranges and along the coast of many regions bordering the Pacific Ocean. The largest earthquakes are generally low-angle shallow dipping reverse faults associated with subduction plate boundaries. Strike-slip faulting indicates neither extension nor compression but identifies regions where rocks are sliding past each other. The San Andreas fault system is a famous example of strike-slip deformation-part of coastal California is sliding to the northwest relative to the rest of North America-Los Angeles is slowly moving towards San Francisco. EARTHQUAKE MAGNITUDE AND INTENSITY Magnitude of earthquake measures amount of energy released from the earthquake. Intensity of earthquake is based on damage to building as well as reactions of people. There are three commonly used magnitude scales to measure magnitude of earthquake. These have been explained below. Local Magnitude Scale ML This scale is also called Richter scale. This scale is calculated as follows Ml log A - log A log A A0
