Archived Articles

Past Quakes Raise Future Concerns

FEMA Study

In a study released in September, 2000, the Federal Emergency Management Administration (FEMA) warned of annual bills of $4.4 billion for damage to cities across the nation at risk from earthquakes. The FEMA researchers used U. S. Geological Survey data on the earthquake hazard of about 150,000 points across the country and added information about local building inventories, economic data and other details to estimate potential losses. The damage estimates include only damage to buildings, not bridges, roads, or other infrastructure. Of the $4.4 billion in annual damage, about $3.26 billion is attributed to California. In addition to California metropolitan areas, cities facing the highest potential losses include Seattle, Portland, OR, New York, Salt Lake City, St. Louis, Tacoma, WA, Las Vegas, Anchorage, Boston, Reno, NV, Memphis, Charleston, SC, Albuquerque, Newark, NJ, and Atlanta For New York City, the damage, averaged over the next 2,500 years, would be only 5 percent of that confronting Los Angeles. Additional non-FEMA research (see below) adds to the information on seismic risks in these cities, and in cities not covered by the FEMA study.

Central and Eastern North America

In 1982 the U.S. Geological Survey (USGS) told the Nuclear Regulatory Commission that an 1886 Charleston, S.C.-size earthquake (M 7.5) could occur anywhere along the eastern seaboard where geological conditions are similar to those near Charleston. As of September 1997, the USGS position had not been successfully rebutted (EOS, 9/2/97, p. 369). Although the USGS study was done to analyze seismic safety issues related to nuclear power plants, it has repercussions for a number of cities from Maine to Florida. Information on some specific eastern and central U.S. cities appears in the abstract volume for the American Geophysical Union's 1998 spring meeting [EOS Trans. AGU 79 (17), Supplement]. (Note: Identifiers like “T36C-2” in the following footnotes refer to numbers assigned to the various abstracts cited from the Transactions volume.)

Boston. This city lies within a region of possible strong seismotectonic effects, as depicted on William Hutton's map of predicted Earth changes. Seismologists1 recently studied patterns of amplification of earthquake ground-motion in the Boston area for nine historical “felt”-earthquake reports in newspapers. They assigned to each report a modified-Mercalli, earthquake-intensity value (see Hutton's "Coming Earth Changes," Table 1, for sale on the Home Page). Ground-shaking was found to be amplified by two or more intensity units over the mean values of the Boston area, mostly in the downtown Boston landfill and Back Bay areas. This is unwelcome news for the many buildings and their occupants in these areas.

New York City. Historically, in most years there are no earthquakes of importance in the New York City area. Three moderate earthquakes (around M5.0) have struck nearby in the last 300 years, and an earthquake that size today would probably cause several billion dollars of damage. Dr. Klaus Jacob, a research scientist at the Lamont-Doherty Earth observatory of Columbia University, is an executive committee member of the New York City Consortium for Earthquake Loss Mitigation. He has estimated that a magnitude 5 quake would cause about $5 billion of damage. But, he has said, when it gets to M6, "that's when it gets nasty. A quake that size would cause about $30 billion of damage."

East-Central U.S. In a similar study of newspaper quake reports, geologists found 240 previously undocumented, historical mainshocks in an area extending from the Midwest to the East Coast. (A mainshock is the largest quake in a series.) “Preliminary results suggest a possible decrease in the overall level of seismicity in the [east-]central U.S. since the mid-19th century and is consistent with the hypothesis that the New Madrid seismic zone [activity] is an aftermath of the 1811-'12 mainshocks.”2 While it's good to find decreasing seismicity, it's also important to remember that when Earth's lithospheric plates begin to move again–in response to a readings'–style pole shift–we may expect sensitive seismic zones like the New Madrid, Mo., zone to be among the first to generate major and great earthquakes. As stated in reading 1152-11:

. . . many portions of the east coast will be disturbed, as well as many portions of the west coast, as well as the central portion of the U.S.

Eastern Kansas. The Nemaha Ridge and Humbolt fault (NRHF) continue to display weak seismicity, particularly near Wamego where a strong 1867 shock occurred.3 The NRHF is discussed in my book, Coming Earth Changes(CEC, pp. 91 and 280), and is shown as an area of potentially strong seismotectonics on the map on p. 291). Topeka and Emporia lie within this area.

Southeastern Arkansas. Six new faults have been located along the Saline River lineament and associated seismicity alignment in the Ouachita Mountain earthquake source zone (see Fig. 14 in CEC).4 The faults lie within an area of projected strong seismotectonic effects on the Earth-changes map. Little Rock, Pine Bluff, and Hot Springs are in this area.

St. Louis and Vincennes. Geologists dig trenches to search for evidence of earthquake-induced soil liquefaction. They can obtain organic material from features like sand dikes that cut clay beds, and from soil slumps to determine by carbon-14 dating just when a quake occurred. The size of liquefaction features can be used to estimate the strength of each quake. Important soil-liquefaction evidence has been reported5 from trenches and outcrops east of St. Louis, Mo., along Shoal Creek and the Kaskaskia River in Illinois. The data suggest that a very large earthquake struck the St. Louis area about 6,500 years ago. The quake's epicenter may have been near Germantown, Ill., and the earthquake itself could have been an M 7.2. Other soil-liquefaction evidence in southeastern Illinois and southwestern Indiana are attributed to another very large earthquake (M 7.5?) centered near Vincennes, Ind., about 6,100 years ago.

Richmond, Va. USGS geologists searched for ancient liquefaction evidence in the Richmond area. They concluded6 that although historical earthquakes as large as M 5.0 or so have struck central Virginia, the “paucity of liquefaction features there makes it seem unlikely that any quakes in excess of about M 7.0 have struck there for at least 2-3,000 years.” The relatively low-seismicity Richmond area lies just beyond the western edge of our revised safety-land boundary for the Earth-changes map.

Los Angeles Basin

Early scenarios for seismic hazards facing urban Los Angeles focused mainly on the effects of a major (M 7.0-7.9) quake generated along the San Andreas fault, located more than 31 miles northeast of central Los Angeles. But in the mid-1980s attention turned to hazards posed by potential earthquakes from faults directly beneath the metropolitan area. Descriptions of two such seismic, fault-hazard zones have just been documented.

Hollywood. The Hollywood fault extends for about 8.5 miles along the southern margin of the eastern Santa Monica Mountains, from the Los Angeles River westward through downtown Hollywood to northeastern Beverly Hills. According to a recent article7, “rupture of the entire Hollywood fault, by itself, could produce an M 6.6 earthquake, similar in size to the highly destructive 1994 Northridge earthquake, but even closer to more densely urbanized areas.”

Santa Monica/Malibu. The 25-mile-long Santa Monica fault lies just to the southwest of the Hollywood fault. It extends through the densely urbanized northwestern Los Angeles area and offshore parallel to the Malibu coast. A recent study8 of this fault shows that multiple earthquakes have recurred along the fault within the last 50,000 years. Six have ruptured the surface. The latest quake, caused by thrusting along the fault, occurred 1-3,000 years ago. This fault is similar to many others in the Los Angeles Basin. Indeed, it has been estimated that six major faults running beneath the basin hold enough accumulated stress to produce seventeen Northridge-size earthquakes.

San Francisco Bay Area

The April 22, 1998, San Francisco Chronicle carries an article by C. Burress about the hazards to the University of California at Berkeley from the next earthquake along the dangerous Hayward fault. “Campus officials have disclosed. . . that the number of buildings rated unsafe in a major quake is now more than 100, almost double the number last fall when UC Berkeley launched a major seismic safety plan.” This total includes the university's 75,000-seat Memorial Stadium, which lies directly on top of the fault and is being torn slowly in half by fault creep. “The northern segment of the Hayward fault is overdue for a major earthquake and could represent the greatest quake-related loss of life in the United States,” writes Burress.

The cost of seismic-safety repairs to the fifty-seven unsafe UC buildings identified last fall exceeds $1 billion–and that does not cover more than fifty offâ��campus structures that fail to meet new earthquake safety standards.

Now, broaden your vision from the UC Berkeley campus to the entire region. The last major quake on the southern Hayward fault, in 1868, knocked down buildings in San Francisco. Mr. Burress quotes UC Berkeley research geologist Patrick Williams as saying, “I shudder to think that even a moderately large earthquake [on the Hayward fault] is the most hazardous earthquake expected in the United States because of the urban development along the fault.” A preview of the destruction that could be expected can be had from the material damage that occurred in the 1995 Kobe, Japan, quake. It amounted to $100 billion.

Now further broaden your vision to accommodate reading 3976-15, which says thatThe early portion [of the coming Earth changes] will see a change in the physical aspect of the west coast of America,” or reading 1152-11 that says,Los Angeles, San Francisco, most all of these will be among those that will be destroyed before New York even.” Have we not by now given enough “loving warnings” to our friends of like mind who dwell on the West Coast? But, you say, what precedent is there for large earthquakes occurring in a coordinated fashion, perhaps all along the West Coast in response to plate movements there? None, I respond, at least not based upon the relatively short historical record of seismotectonics for California. Is it really possible, then, that Cayce-readings'-style upheavals might happen there?

With plenty of stress stored in the fault zones of the Los Angeles Basin, the San Francisco Bay Area, and elsewhere along the U.S. Pacific coast, it is theoretically possible for the entire West Coast to experience breaking-up (3976-15) if the Pacific and/or the North American plates were suddenly to experience modestly accelerated movement. But it would probably require the beginning of a pole shift for this to happen.


  1. Hart, K., and J. Ebel, T32C-2 <back>
  2. Armbruster, J., et al., T32C-4 <back>
  3. Neimi, T., T32C-11 <back>
  4. Cox, R., et al, T41A-2 <back>
  5. Tuttle, M., et al, T41A-10 <back>
  6. Obermeir, S., and McNulty, W., T41A-9 <back>
  7. Dolan, J., et al., "Active Tectonics, Paleoseismology, and Seismic Hazards of the Hollywood Fault, Northern Los Angeles Basin, California." Geological Soc. Amer. Bull., v. 109, no. 12, 1997 <back>
  8. Pratt, T., etg al. "Multiscale Seismic Imaging of Active Fault Zones for the Santa Monica Fault Zone." Geophysics, v. 63, no. 2, 1998. <back>