IS THERE A NEAR-FIELD FOR SMALL-TO-MODERATE MAGNITUDE EARTHQUAKES?

The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be unconservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater.     

Here Lies the Supreme Court: Revisited

相似文献   

Textual Corruption in the Civil Rights Cases

The Civil Rights Cases ¹ do not quite rival Plessy v. Ferguson ² for notoriety as the decision that most clearly confirmed the failure of Reconstruction and the rise of Jim Crow. Yet the Civil Rights Cases did far more than Plessy to limit federal power to address the continuing consequences of slavery. They declared unconstitutional the Civil Rights Act of 1875 insofar as it prohibited discrimination in public accommodations operated by private parties. Congress passed that act under its powers to enforce the Thirteenth and Fourteenth Amendments, but the Court held the act unconstitutional on the ground that private discrimination was neither a badge or incident of slavery under the Thirteenth Amendment nor a manifestation of state action under the Fourteenth. Although the Court's holding under the Thirteenth Amendment was effectively overruled by the Warren Court, ³ its holding under the Fourteenth Amendment continues to be influential, supporting a decision of the Rehnquist Court striking down the Violence Against Women Act. ⁴