EERI Washington Chapter Meeting: September 9th



Dr. Ben Mason
Associate Professor, Oregon State University

Monday, September 9, 2019

5:30 PM Reception (Drinks and appetizers will be served)
6:15 PM EERI WA Board Welcome
6:30 PM Lecture

Seattle Public Library
Washington Mutual Foundation Meeting Room 
1000 Fourth Ave.
Seattle, WA 98104-1109

FREE Admission – RSVP HERE

Flowslides Initiated by the 28 September 2018 MW7.5 Palu-Donggala Earthquake
The MW7.5 Palu-Donggala earthquake occurred on 28 September 2018 in Sulawesi, Indonesia. The strike-slip earthquake rupture occurred on the Palu-Koro fault, which runs north-south through Central Sulawesi. The Palu-Donggala earthquake triggered a series of large landslides (or flowslides) throughout the Palu Basin. In general, the large flowslides initiated beneath moderate slopes (i.e., grades between 2 to 6 percent) and significant liquefaction, as evidenced by numerous sand boils, occurred within the flowslides’ footprints. Given the large footprints of the flowslides as well as the population density of the Palu Basin, the flowslides claimed lives, destroyed hundreds of houses, and left a heavily-used irrigation canal inoperable. A National Science Foundation funded Geotechnical Extreme Events Reconnaissance (GEER) team traveled to Palu to conduct post-earthquake field reconnaissance from 11 November to 17 November 2018. We documented the geologic setting, collected perishable field data, and obtained eyewitness accounts to understand the mechanisms responsible for initiation and progression of the large flowslides. To assist the post-earthquake reconnaissance, we performed high-resolution mapping using a DJI Inspire 2 unmanned aerial vehicle (UAV, or “drone”) mated with a Zenmuse X4S camera (1-inch sensor, with 20 MP resolution). We used Pix4D mapper to process the ground-controlled unmanned aerial vehicle photographs, and we developed high-resolution orthomosaic images and digital elevation models. Within this talk, I will report the findings of our post-earthquake reconnaissance efforts and propose hypothesized mechanisms responsible for flowslide initiation and progression. Our interpretations are aided by cone penetration tests performed after our initial reconnaissance effort.

Ben Mason, Ph.D.
Associate Professor, College of Engineering
Oregon State University

  Ben’s primary field of research interest is natural hazards engineering. Within this broad field, he has interests in geotechnical earthquake engineering, including soil-structure interaction and residual soil liquefaction as well as coastal geotechnical engineering, including fluid-soil-structure interaction, momentary soil liquefaction, and tsunami-induced scour. He has a particular interest in how a combined earthquake and tsunami event affects coastal soil instability and ultimately the stability of coastal buildings and infrastructure. He uses physical modeling techniques coupled with numerical and analytical modeling to investigate his aforementioned research interests. He is also interested in the fields of sustainable geotechnical engineering and geotechnical engineering education. He participates in post-earthquake reconnaissance events to motivate and strengthen his research and teaching interests.