Editing Portland, Oregon (section)

===Geology===
{{see also|Geology of the Pacific Northwest}}
Portland lies on top of a dormant volcanic field known as the [[Boring Lava Field]], named after the nearby [[commuter town|bedroom community]] of [[Boring, Oregon|Boring]].<ref name="volcano">{{cite web|title=The Boring Lava Field, Portland, Oregon|publisher=United States Geological Survey Cascades Volcano Observatory|url=http://vulcan.wr.usgs.gov/Volcanoes/Oregon/BoringLavaField/description_boring_lava.html|access-date=November 7, 2006|archive-date=July 1, 2011|archive-url=https://web.archive.org/web/20110701101745/http://vulcan.wr.usgs.gov/Volcanoes/Oregon/BoringLavaField/description_boring_lava.html|url-status=dead}}</ref> The Boring Lava Field has at least 32 cinder cones such as [[Mount Tabor, Portland, Oregon|Mount Tabor]],<ref>{{cite web|title=Mount Tabor Cinder Cone, Portland, Oregon|publisher=United States Geological Survey Cascades Volcano Observatory|url=http://vulcan.wr.usgs.gov/Volcanoes/Oregon/BoringLavaField/VisitVolcano/mount_tabor.html|access-date=April 20, 2007|archive-date=July 16, 2012|archive-url=https://web.archive.org/web/20120716231818/http://vulcan.wr.usgs.gov/Volcanoes/Oregon/BoringLavaField/VisitVolcano/mount_tabor.html|url-status=dead}}</ref> and its center lies in southeast Portland. [[Mount St. Helens]], a highly active volcano {{convert|50|mi|km}} northeast of the city in Washington state, is easily visible on clear days and is close enough to have dusted the city with volcanic ash after its [[1980 eruption of Mount St. Helens|eruption on May 18, 1980.]]<ref>{{Cite news|title=History, relived saved from St. Helens by a six-pack of Fresca|last=Nokes|first=R. Gregory|date=December 4, 2000|work=The Oregonian|page=17}}</ref> The rocks of the Portland area range in age from late [[Eocene]] to more recent eras.<ref>{{cite book|author=Trimble, Donald|title=Geology of Portland, Oregon and Adjacent Areas|pages=1–2|publisher=Geological Survey Bulletin|year=1963|url=https://pubs.usgs.gov/bul/1119/report.pdf}}</ref>

Multiple shallow, active [[Fault (geology)|fault lines]] traverse the Portland metropolitan area.<ref name=banse>{{cite web|work=Oregon Public Broadcasting|url=https://www.opb.org/news/series/unprepared/pacific-northwest-oregon-washington-earthquakes-faults-cascadia/|author=Banse, Tom|title=Geologists Keep Finding More Northwest Earthquake Faults|date=November 21, 2017|access-date=May 10, 2018|archive-date=May 10, 2018|archive-url=https://web.archive.org/web/20180510184616/https://www.opb.org/news/series/unprepared/pacific-northwest-oregon-washington-earthquakes-faults-cascadia/|url-status=dead}}</ref> Among them are the [[Portland Hills Fault]] on the city's west side,<ref>{{cite web|url=http://www.oregonlive.com/environment/index.ssf/2011/02/comparing_portlands_quake_risk.html|title=Comparing Portland's quake risk to that of devastated Christchurch, New Zealand|newspaper=The Oregonian|date=February 23, 2011|author=Rojas-Burke, Joe|access-date=May 9, 2018}}</ref> and the [[East Bank Fault]] on the east side.<ref>{{cite news|work=Willamette Week|url=http://www.wweek.com/news/2010/01/26/quake-up-call/|date=January 26, 2010|access-date=May 9, 2018|title=Quake-Up Call|author=Mesh, Aaron}}</ref> According to a 2017 survey, several of these faults were characterized as "probably more of a hazard" than the [[Cascadia subduction zone]] due to their proximities to population centers, with the potential of producing [[Richter magnitude scale|magnitude]] 7 [[earthquake]]s.<ref name=banse/> Notable earthquakes that have impacted the Portland area in recent history include the 6.8-magnitude [[2001 Nisqually earthquake|Nisqually earthquake]] in 2001, and a 5.6-magnitude earthquake that struck on March 25, 1993.<ref>{{cite journal|author1=Bott, Jacqueline D.J.|author2=Wong, Ivan G.|title=Historical Earthquakes in and around Portland, Oregon|date=September 1993|journal=Oregon Geology|volume=55|issue=5|page=116}}</ref><ref>{{cite book|title=The Nisqually, Washington, Earthquake of February 28, 2001|url=https://books.google.com/books?id=W5-B40vrljIC&pg=PA29|editor-first=P. W.|editor-last=McDonough|date=2002|series=Open-File Report 2002-346|publisher=[[American Society of Civil Engineers]]|pages=28, 29|isbn=978-0-7844-7516-4}}</ref>

Per a 2014 report, over 7,000 locations within the Portland area are at high risk for landslides and [[soil liquefaction]] in the event of a major earthquake, including much of the city's west side (such as [[Washington Park, Portland, Oregon|Washington Park]]) and sections of [[Clackamas County, Oregon|Clackamas County]].<ref name=seventh>{{cite web|publisher=KATU|url=http://katu.com/news/local/7000-high-risk-landslide-zones-in-portland-area-check-if-you-live-in-one|title=7,000 high-risk landslide zones in Portland area; check if you live in one|date=March 24, 2014|author=Cassuto, Dan|access-date=May 9, 2018|archive-url=https://web.archive.org/web/20170207113202/http://katu.com/news/local/7000-high-risk-landslide-zones-in-portland-area-check-if-you-live-in-one|archive-date=February 7, 2017}}</ref>