This morning, representatives of the team met with engineers from the Irrigation Unit from Public Works Department. Some productive discussions were had, with Irrigation Unit sharing information very generously, and EEFIT/TDMRC discussing our preliminary thoughts in return. Some members then met with BMKG (Institute of Geophysics, Meteorology and Climatology), who presented some of the useful maps they had prepared.
In the afternoon, the Geo team traced the fault rupture south from its emergence at Palu Bay, where the left lateral strike slip fault had displaced by approximately 4m at the coast, clearly visible across a major road, now partly submerged. Back from the coast, the fault was visible across road crossings heading southwards. About 600m back from the shore and crossing the fault, a field of liquefaction sand ejecta was seen, with clear displacements of 300 mm relative to nearby intact ground. The fault then led the team to further liquefaction sites in Lasoso area, with housing and Majid Iqra Mosque affected, the latter exhibiting spectacular tilting of minarets and extensive sand ejecta. The team then followed the fault rupture as far south as daylight permitted, measuring reducing slip displacements down to 2.5m in increasingly rural environments.
Another part of the EEFIT-TDMRC was joined by Indra from Save the Children to conduct structural surveys of representative school complexes affected by the earthquake ground shaking. Overall, 4 schools compounds with more than thirty school buildings were surveyed. These structures were mainly confined masonry and reinforced concrete brick-infilled frame buildings and showed a variety of damage levels and mechanisms. The latter included damage from ground settlement and out of plane collapse of confined masonry walls.
In addition, a small team left to survey inundation and tsunami damage starting at Mamboro on the east coast, working around to end at the mouth of the Palu river in Palu Bay. The team interviewed several residents along the way who lived in houses close to the coastline. One interview was particularly remarkable as the man recounted that he had been swimming in the sea at the time of the earthquake. He left the water after the earthquake and persuaded his family to run up the nearby hill, but he remained to watch the wave. Waiting near his house, he noticed a child by the shoreline who was in the path of the oncoming wave. He dashed forward, grabbed the child but could not run back to safety quickly enough and both were engulfed by the wave. Thankfully, both survived though the child couldn’t walk for 2 weeks due to injuries he sustained.