State Department of Geology and Mineral Industries releases coastal maps showing tsunami inundation line

The Oregon Department of Geology and Mineral Industries (DOGAMI) has just released 58 maps showing the tsunami inundation zone along the Oregon coast. Each map has a line that shows how far inland and uphill a tsunami caused by a magnitude 8.8 undersea earthquake is expected to go. The new maps were developed to implement Oregon Revised Statutes 455.446 and 455.447, a law passed by the 1995 Legislature to restrict construction of certain types of essential facilities and special occupancy structures within the tsunami inundation zone. The line was developed from studies of prehistoric tsunami deposits found along the coast, computer modeling by Dr. George Priest of DOGAMI and Dr. Antonio Baptista of the Oregon Graduate Institute of Science & Technology, and scientific studies of other tsunamis that occurred in Nicaragua and Japan.

Each of the blueline diazo maps is on a US Geological Survey 7-minute topographic map base and is at a scale of 1:24,000. Each map is printed as a separate open-file report, with an individual number. On the reverse side of this sheet is an index map showing the names and locations of each of the tsunami maps. Cost of each map is $3. A complete set of all 58 maps costs $160. Included with each map is a copy of Oregon Revised Statutes 455.446 and 455.447, Oregon Administrative Rules 632-05 that implement the maps, and a map index.

The method used to develop the inundation line is explained in a newly released DOGAMI open-file report entitled Explanation of Mapping Methods and Use of the Tsunami Maps of the Oregon Coast. This new report, numbered Open-File Report O-95-67, has 100 pages and contains an explanation of the methodology used to develop the tsunami inundation line, detailed graphs showing tsunami run-up for areas along the open coast, and the sequence and timing of tsunami waves (time histories) at selected coastal population centers. The cost of this report is $9.

These maps and open-file report may be purchased over the counter or by mail, fax, or phone from the Nature of the Northwest Information Center, Suite 177, 800 NE Oregon Street #5, Portland, OR 97232-2162, phone 503-872-2750, fax (971) 673-1562. Orders may be charged to Visa or Mastercard. Orders under $50 require prepayment except for credit card orders.