The 1992 Cape Mendocino earthquake raised a twelve mile stretch of the coast near Cape Mendocino as much as four feet. Photo by Ron LeValley
The 1992 Cape Mendocino earthquake raised a twelve mile stretch of the coast near Cape Mendocino as much as four feet. Photo by Ron LeValley
Will California fall into the ocean? California cannot fall into the ocean because it is firmly attached to the earth's crust. A big earthquake however, could produce landslides on cliffs and unstable ground. Very big subduction zone earthquakes can change the shape of the coastline by uplifting and downdropping different areas by a number of feet. Speculating on future coastline property in Nevada or Arizona is a very poor bet!
Big earthquakes always happen in the early morning. Earthquakes can happen at any time of the day or year. A number of notable earthquakes have occurred in the early hours including Northridge, Kobe, and the 1906 San Francisco earthquake. Just as many have occurred at other times including Loma Prieta (5:04 p.m.), Cape Mendocino (11:06 a.m.) and the Great Alaskan quake of 1964 (5:36 p.m.).
It is warm and dry - earthquake weather! Many people are convinced certain kinds of weather precede strong earthquakes. Scientists have looked for linkages between daily weather, time of day and time of year but no correlation has been found. Daily temperature fluctuations caused by weather only penetrate a few tens of feet into the ground. Earthquakes are generated miles beneath the surface where temperatures are governed by the heat coming from within the earth, not the outside.
Can explosions cause earthquakes? Some people are afraid setting off explosions underground may trigger large earthquakes. There is no evidence to support this idea. Explosions are frequently used to quarry rocks, to explore subsurface geology, and to locate earthquakes more accurately. These explosions may release the energy equivalent to a magnitude 2 earthquake. Waves hitting the coast in a big storm put more energy into the ground than these explosions.
I have just heard that someone has predicted an earthquake for next week.... Within a few days after every significant earthquake, rumors will begin to circulate about someone predicting a major earthquake in the near future. The State Office of Emergency Services may issue probability estimates for aftershocks based on information from the U.S. Geological Survey. These should not be confused with the prediction of a particular event.
Small earthquakes prevent big ones from happening. Not true. Earthquakes are natures way of releasing energy. Each magnitude level represents about 30 times more energy released. It takes 30 magnitude 3 earthquakes to release the energy of a magnitude 4 earthquake, 900 magnitude 3s to equal a magnitude 5, 27,000 magnitude 3s to equal a 6 and so forth. This requires 10,000 magnitude 3 earthquakes every year for 300 years to release the energy of a single magnitude 9!
The safest place to be in an earthquake is under a doorway. Doorways in homes and modern buildings are no stronger than the rest of the structure and usually have a door which can swing and injure you. In a public building, you may also be injured by people crowding into a doorway or trying to get outside.
The safest place to be in an earthquake is under a doorway. Doorways in homes and modern buildings are no stronger than the rest of the structure and usually have a door which can swing and injure you. In a public building, you may also be injured by people crowding into a doorway or trying to get outside.
Disaster assistance depends on the magnitude of the earthquake. When a disaster occurs, the local jurisdiction makes an initial damage assessment and may request state assistance. If state resources are insufficient, the Governor requests the President to declare a major disaster and the Federal Emergency Management Agency becomes involved. It is the magnitude of the damage, not the earthquake, which determines the level of response. Once a major disaster is declared, the type and level of federal assistance are the same regardless if the earthquake had a magnitude of 6.2 or 8.2.
Federal Emergency Management Agency, (FEMA), Building 105, The Presidio, San Francisco, CA 94129, (415) 923-7100. Information and publications on earthquake preparedness. Documents should be ordered from FEMA, P.O. Box 70274, Washington, D.C. 20024.
U.S. Geological Survey (USGS), Earth Science Information Center Menlo Park, CA 94025, 345 Middlefield Road, (415) 329-4390. Publications and maps concerning earthquake hazards. Mail orders to USGS Books and Report Sales, P.O. Box 25425, Denver, CO 80225. For orders less than $10.00, include $1.00 P&H.
Governors Office of Emergency Services, Coastal Region, Earthquake Program, 1300 Clay Street, Suite 400, Oakland, CA 94612-1425, (510) 286-0873. Publications, videotapes, and scripted slide shows on earthquake preparedness. Free catalog.
California Department of Conservation, Division of Mines and Geology (CDMG), P.O. Box 2980, Sacramento, CA 95812-2980, (916) 445-5716. Publications and maps concerning faults. Scenarios describing the likely effects of future earthquakes.
California Seismic Safety Commission, 1900 K Street, Suite 100, Sacramento, CA 95814-4186. Information about legislation, state agency programs and unreinforced masonry building programs. Additional information on residential and commercial building hazard mitigation.
Oregon Department of Geology and Mineral Industries (DOGAMI), 800 NE Oregon Street #28 suite 965, Portland, OR 97232, (503) 731-4100. For information on earthquakes and tsunamis in Oregon.
Department of State Police, Oregon Emergency Management, 595 Cottager Street, NE, Salem, OR 97310, (505) 378-2911. For information about emergency preparedness. International Tsunami Information Center, Box 50027, Honolulu, HI, 96850-4993, (808) 541-1658. For information on tsunamis.
Humboldt Earthquake Education Center, Humboldt State University, Arcata, CA 95521, (707) 826-6019. For information on north coast earthquakes, tsunamis and preparedness.
The Humboldt Earthquake Education Center is a non-profit organization operating within the Department of Geology, Humboldt State University. The primary purpose of the Center is to provide information on North Coast earthquakes, California seismicity and to foster earthquake awareness, preparedness and education programs in elementary, Jr. High and Sr. High Schools, and for the general public. Activities of the Center include:
See our page on the World Wide Web - http://www.humboldt.edu/~geology/earthquake/eqk_info.html
Humboldt County ARC, P.O. Box 3402, Eureka, CA 95502 (707) 443-4521.
Lake County ARC, P.O. Box 3132, Clear Lake, CA 95422 (707) 994-0640.
Mendocino County ARC, P.O. Box 953, Ukiah, CA 95482 (707) 463-0112.
Siskiyou County ARC, P.O. Box 252, Yreka, CA 96097 (916) 842-4476.
Shasta Area (includes Trinity and Lassen Counties) ARC, 2280 Benton Drive, Redding, CA 96003 (916) 243-3021.
Curry County ARC, 850 Chetco Avenue, Brookings, OR 97415 (503) 469-0552.
Del Norte County OES, 450 H Street, Room 208, Crescent City, CA 95531 (707) 464-7213.
Humboldt County OES, 825 5th Street Eureka, CA 95501 (707) 445-7395.
Lake County OES, 375 3rd Street, Lakeport, CA 95490, (707) 263-2201.
Mendocino County OES, 17501 N. Hwy. 101, Willits, CA 95490 (707) 459-7469.
Siskiyou County OES, 800 S. Main, Yreka, CA 96097 (916) 842-8011.
Trinity County OES, P.O. Box 1228, Weaverville, CA 96093 (916) 623-1227.
Curry County OES, P.O. Box 746 Gold Beach, OR 97444 (503) 247-7011 ext. 208.
This publication is meant to be instructional and to provide information that will help you understand and reduce the risk from earthquakes and tsunamis. The information in this publication is believed to be accurate at the time of publication. The agencies and individuals involved in the preparation, printing, and distribution of this publication assume no responsibility for any action that is based on the information found in this publication.
Prepared by the Humboldt Earthquake Education Center, Humboldt State University in cooperation with the Federal Emergency Management Agency and the California Office of Emergency Services.
Written and compiled by Lori Dengler and Kathy Moley; art direction and design by Jay Brown, all of Humboldt State University.
Tsunami inundation zones shown on page 9 are based on National Oceanic and Atmospheric Administration Technical Memorandum ERL PMEL-103, Tsunami Inundation Model Study of Eureka and Crescent City
Additional contributions: Linda Nellist and Denise Schanbeck, Humboldt County OES; Sarah Nathe, State OES Earthquake Program; Sean Kearns, Gary Carver, both of Humboldt State University, NOAA and Oregon DOGAMI provided information on tsunamis. Deborah Carver and Jean Perry assisted with native stories. Mike Pasyanos, Seismographic station U.C. Berkeley provided seismograms. Jim Dewey, U.S. Geological Survey, Denver CO compiled seismicity map. Yurok legend from Yurok Myths, A. L. Kroeber, 1976, University of California Press, Berkeley.
Photo Services: Cheryl Easter and Dar Spain both at Humboldt State University.
Photos supplied by: Lori Dengler, Kevin Bayless, Lindie Brewer, Carol Prentise, Andrew Larson, Henry Helbush, Del Norte Historical Society, Ron LeValley, California Office of Emergence Services, California Division of Mines and Geology, U.S.G.S. and the National Geophysical Data Center.
Printing by Humboldt Printing Company.
Much of the text was reprinted from On Shaky Ground: Living with Earthquakes on the North Coast, Humboldt Sate University, 1993. The concept came from The Next Big Earthquake in the Bay Area May Come Sooner than You Think, by Peter Ward, USGS.
Lori Dengler (lad1@axe.humboldt.edu) Kathy Moley (km2@axe.humboldt.edu)
