Answer:

Earthquake:

• An earthquake is a series of vibrations on the earth’s surface caused by the generation of seismic waves due to sudden rupture within the earth during release of accumulated strain energy. Due to constant movement of continental plates, deformation is caused which results to generations of strain energy.
• Indian plate is moving in north-north east direction and colliding with Eurasian plate along the Himalayas. All earthquakes, let it be the Arunachal Pradesh China Earthquake (1950), Gujarat Earthquake, Bhuj (26 Jan 2001, Magnitude 7.7), Sumatra Earthquake (2004, Magnitude 9.3), Kashmir Earthquake (2005) have same story to tell.
• Severity of an Earthquake is measured on Richter scale in following terms:

1. Slight - Magnitude up to 4.9 in a Richter Scale
2. Moderate - Magnitude up to 5 to 6.9 in a Richter Scale
3. Great - Magnitude up to 7.0 to 7.9 in a Richter Scale
4. Very Great - Magnitude up to 8.0 and more

• Because of earthquake humanity suffers a lot. That’s why management of earthquake has become very crucial in this trouble times. But before we make any plan we need to focus on some critical areas that need attention for effective Earthquake Management are:

1. Lack of awareness among various stakeholders about the seismic risk;
2. Inadequate attention to structural mitigation measures in the engineering education syllabus;
3. Inadequate monitoring and enforcement of earthquake-resistant building codes and town planning bye-laws
4. Absence of earthquake-resistant features in non-engineered construction in suburban and rural areas;
5. Lack of formal training among professionals in earthquake-resistant construction practices; and
6. Lack of adequate preparedness and response capacity among various stakeholder groups.

Tsunami:

• A tsunami earthquake triggers a tsunami of a magnitude that is very much larger than the magnitude of the earthquake as measured by shorter-period seismic waves.
• The term was introduced by Hiroo Kanamori in 1972. Such events are a result of relatively slow rupture velocities. They are particularly dangerous as a large tsunami may arrive at a neighbouring coast with little or no warning.
• The distinguishing feature for a tsunami earthquake is that the release of seismic energy occurs at long periods (low frequencies) relative to typical tsunamigenic earthquakes. Earthquakes of this type do not generally show the peaks of seismic wave activity associated with ordinary events.
• A tsunami earthquake can be defined as an undersea earthquake for which the surface wave magnitude Ms differs markedly from the moment magnitude Mw, because the former is calculated from surface waves with a period of about 20 seconds, whereas the latter is a measure of the total energy release at all frequencies.
• The displacements associated with tsunami earthquakes are consistently greater than those associated with ordinary tsunamigenic earthquakes of the same moment magnitude, typically more than double. Rupture velocities for tsunami earthquakes are typically about 1.0 km per second, compared to the more normal 2.5–3.5 km per second for other megathrust earthquakes.
• These slow rupture speeds lead to greater directivity, with the potential to cause higher run-ups on short coastal sections. Tsunami earthquakes mainly occur at subduction zones where there is a large accretionary wedge or where sediments are being subducted, as this weaker material leads to the slower rupture velocities