The Aceh earthquake in December 26, 2004 had a magnitude of 9.3 and resulted a huge tsunami in Indian ocean and killed more than 200000 people. The great Nias earthquake of March 28, 2005 ruptured another segment next to the Aceh earthquake segment. The South Sumatra earthquake occurred on September 12, 2007 and had a magnitude of 8.4. The estimated rupture length is about 270-300 km long. Now there is an unbroken segment facing Padang City of West Sumatra Province of Indonesia (Figure 2.7). The unbroken part is more than 400km and it may result in mega-thrust earthquake with a magnitude greater than 8.7.
Results of geotechnical drilling and cone penetration tests to the depth 30 m in Padang City indicated that the soil layers consist of mainly loosely to densely-packed sand and soft silty clay layers. The liquefaction susceptibility analyses show that the soil layer is potentially prone to liquefaction.
Padang city is located on a very flat land. It is about 3km to reach the altitude of 5m from the coast, In case of Tsunami with a height of more than 5m, it may be quite disastrous.
A Reconnaissance Report on The Pariaman-Padang Earthquake