DOE 2000. - Waste Isolation Pilot Plant - U.S. Department of Energy

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 2
2.5 Vibratory Ground Motion
This section is directed towards establishing the seismic design basis for vibratory ground motion
directly applicable to Design Class I and II confinement structures and components at the WIPP facility.
The application of the results contained in this section to seismic design of plant facilities is discussed in
Section 3.2.7. This presentation is aimed at conservatively estimating the Design Basis Earthquake
(DBE) for the WIPP site facility.
The approach used in this analysis is to develop a probabilistic peak acceleration to be used in design.
This peak acceleration is derived from a correlation between historical earthquake activity and various
active geologic structures and tectonic provinces. These results are used to establish the site’s DBE in
Section 2.5.5.
2.5.1 Seismicity
In this section, data are presented for earthquakes within 180 mi (290 km) of the WIPP facility. This area
is defined as the WIPP facility region for this discussion. The information for the WIPP facility region
earthquakes before 1962 is based on chronicles of the effects of those tremors on people, structures and
land forms (called macroseismic evidence). Virtually all information on earthquakes occurring after the
beginning of 1962 in the WIPP facility region is derived from instrumental data recorded at various
seismograph stations.
2.5.1.1 Pre-1962 Earthquake Data
Most earthquakes reported in New Mexico before 1962 occurred in the Rio Grande Valley area between
Albuquerque and Socorro, a distance of more than 186 mi (300 km) from the WIPP site. About half of
the earthquakes of Modified Mercalli Intensity (MMI) V or greater in New Mexico between 1868 and
1973 were in this region. In conformity with previous studies, 1,2,3 those events are not of immediate
concern to this study. There has been one earthquake associated with moderate to considerable damage
(intensity VIII) prior to 1962 within the WIPP facility region. The Valentine, Texas earthquake of 1931,
occurred about 120 mi (193 km) south-southwest of the location of the WIPP facility. The area within
120 mi (193 km) of the WIPP facility has experienced only
low-intensity earthquakes (intensity V or less).
Figure 2.5-1 shows locations of earthquakes occurring before 1962 within 186 mi (300 km) of the WIPP
site. These epicenters were assigned on the basis of macroseismic evidence and are also listed in Table
2.5-1. Supplemental descriptive material for most of those events is provided primarily by Sanford and
Toppozada 1 and other sources. 4,7 All intensities listed in Table 2.5-1 are Modified Mercalli Intensities. 7
An abridged version of this scale is presented in Table 2.5-2.
The Valentine, Texas earthquake of August 16, 1931 was large enough to generate significant interest so
that much more data are available for that event. A number of isoseismal maps were compiled soon after
its occurrence. 5,7 Recently, Sanford and Toppozada assigned MMI on the basis of descriptions of the
effects of this event and plotted the resulting isoseismal map reproduced in Figure 2.5-2. Several features
of this plot are noteworthy. First, according to Figure 2.5-2, the intensity location of the WIPP facility
from this earthquake was V. Second, isoseismal lines close to the zone of the highest intensity are
elongated northwest-southeast conforming to the structural integrity of the region.
2.5-1 January 24, 2003