Nepal Hazard Risk Assessment - Asia-Pacific Gateway for Disaster ...

Nepal Hazard Risk Assessment
3.2.5 HOW TO READ THE MAPS
If the return period is higher, the scenario will be more critical. Based on MMI distribution, the hazard
zones are calibrated. Table 3.1 shows the relationship between intensity and severity zones. Very high
seismic risk has been demarcated by red colour, followed by orange, light brown-yellow and yellow
colour representing high, medium and low seismic zone respectively. The map further shows
geographical coverage of low, medium and high seismic zones.
Table 3.1. Earthquake hazard zone scale
Zone MMI range Color
Low < VI Yellow
Medium VI Light brown‐yellow
High VII Orange
Very
high > VII Red
3.2.6 ANALYSIS OF HAZARD ASSESSMENT
Figure 3.7 - Figure 3.10 show seismic hazard zoning maps for various return periods of 500 years, 250
Years, 100 years and 50 years respectively. Table 3.2 - Table 3.5 shows corresponding districts coverage
of various zones for stated return periods. As the return period increases, the risk zone increases
accordingly. Following paragraph explains the earthquake hazard assessment outcomes.
Figure 3.3 shows scatter plot of percentage hazard area to total area. Very high hazard points tend to
cluster near top (100%). A lot of districts area completely falling within very high earthquake risk.
Under 500 Years return period earthquake hazard mapping, 29 districts including Sankhuasabha,
Bhojpur, Khotang, Okhaldhunga, Siraha, Dhanusha, Mahottari, Sindhuli, Ramechhap, Kabhrepalanchok,
Lalitpur, Bhaktapur, Kathmandu, Nuwakot, Dhading, Lamjung, Kaski, Tanahu, Syangja, Parbat,
Baglung, Myagdi, Gulmi, Rukum, Jajarkot, Dailekh, Kalikot, Accham, Baitadi are completely falling
under very high earthquake risk.
Result maps (Figure 3.7 - Figure 3.10) are presented for different earthquake return years periods. Each
map is accompanied with tables (Table 3.2 - Table 3.5) showing zone area distribution within each
district as per format given in Figure 3.2. The maps contain country wise distribution of each hazard
zone class in graphical format, and geo development regions area distribution.
Figure 3.2. Visualization guideline.
Figure 3.3. Hazard vs total area cross plot for 500 year return period.
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