DOGAMI Coastal Science in Action —
DOGAMI teamed with the Civil Air Patrol (CAP) and the U.S. Coast Guard to to simulate response to a major Cascadia subduction zone earthquake along the Oregon Coast.
Soils buried by tsunami and dune sand at Bahia Cocotué on Isla Chiloé, evidence of centuries of great subduction earthquakes in south-central Chile.
DOGAMI Coastal Science Professional Outreach —
As part of a 2009 GSA field trip Rob Witter discussed research findings on tsunamis and the effects of coastal subduction caused by great earthquakes on the Cascadia Subduction Zone.
Stratigraphic evidence of the 1960 Chile earthquake and tsunami and their predecessors at Maullín, Chile.
Tsunami Hazard Zone sign in Maullin, Chile.
Taking sediment core samples near Nehalem to look for evidence of tsunami deposits. Evidence of the frequency of past tsunamis helps assess future risk.
Workers paint a line in a city street marking the edge of the tsunami evacuation zone in Valparaiso, Chile.
Vibracoring on Cox Island in June 2007. DOGAMI geologists use vibracores to examine tsunami deposits and study stratigraphic evidence of coastal subsidence caused by Cascadia earthquakes.
Field work at Yaquina Bay in June 2010.
The Oregon coast has a justly deserved, worldwide reputation for its spectacular scenery. Because the coast lies at the interface between land and the Pacific Ocean, it is a zone of great instability and vulnerability, creating geologic hazards that can put people and property at risk. DOGAMI scientists work with coastal communities to identify these coastal hazards. In 2000, DOGAMI opened a Coastal Field Office in Newport to expand on the important ongoing research and mitigation efforts that will help minimize the effects of coastal geologic hazards.
This program provides the next generation of tsunami inundation maps along the state’s 362-mile-long Pacific coastline. The primary goal of Oregon’s five-year plan (2009 to 2013) is to reduce loss of life and property damage from tsunamis. Two other components of the program involve development of mitigation products that promote community preparedness and implementation of a coast-wide, volunteer-driven education and outreach initiative to support the National Weather Service’s TsunamiReady™ program.
Differences in earthquake rupture scenarios for the Cascadia subduction zone contribute large uncertainties for simulations of tsunami inundation used to mitigate risk along the U.S. Pacific Northwest coast. Marine and coastal paleoseismic evidence now offer rare insight into rupture variability over multiple Cascadia earthquake cycles.
Marine and coastal paleoseismic evidence for Cascadia subduction earthquakes imply a range of rupture scenarios that provide model inputs for tsunami simulations. Coastal paleoseismic records spanning the past ~7000 yr include 13 tsunami deposits archived in Bradley Lake in southern Oregon. We test the smallest Cascadia tsunami scenarios capable of reaching the lake for consistency with paleoseismic data.
This study applies a simple sediment transport model, TsuSedMod (Jaffe and Gelfenbaum, 2007), to reconstruct the flow speed of the most recent Cascadia tsunami that flooded the region in 1700 using the thickness and grain size of sand layers deposited by the waves.
Three tsunamis triggered by great earthquakes on the Cascadia subduction zone have inundated Nestucca Bay, Oregon over the past 2000 years. The primary evidence includes layers of sandy sediment that bury tidal marshes submerged by earthquake-related subsidence.
The 2004 Indian Ocean magnitude 9.3 Sumatra-Andaman Islands earthquake and subsequent tsunami led to a re-evaluation of DOGAMI's tsunami hazard mapping approach. DOGAMI is leading a technical team of researchers and scientists using the latest technology in terrain mapping (lidar) and computer simulation to produce new tsunami inundation and evacuation maps for the entire Oregon coast. Cannon Beach served as the initial test site for this effort.
Last DOGAMI inundation map using the 1997 approach.
First DOGAMI tsunami inundation map project.