Velocities at Nevada Network Stations

2 PROPOSAL INFORMATION SUMMARY

1. Regional Panel Destinations: NI 2. Project Title: Shear Velocities and Site Amplifications at Nevada and Eastern California Stations Needed for Instrumental Acceleration Mapping 3. Principal Investigator(s): John N. Louie Tel.: (775) 784-4219, Email: [email protected]

John G. Anderson Tel.: (775) 784-4265, Email: [email protected]

Seismological Laboratory MS 174 University of Nevada, Reno, NV 89557 Fax: 775-784-1833 4. Authorized Institutional Dr. Richard Bjur Representative: Acting Director, Office of Sponsored Project Admin. University of Nevada, Reno, NV 89557 Tel.: (775)784-4040, Fax (775)784-6064 Email: [email protected] 6. Element Designation I, II 7. Key Words Site effects, Amplification, Engineering seismology, Real-time earthquake information 8. Amount Requested $56,378 9. Proposed start date January 1, 2002 10. Proposed Duration 1 year 11. New Proposal Yes 12. Active Earthquake-related USGS/NEHRP, Seismic hazard in the vicinity of Las Vegas and Research: Grants, and Level of Reno, $100,000-Anderson, Zeng, Su, and Louie. Support NSF-SCEC, NSF-SCEC, Site Response Investigations at Critical Precarious Rocks Near the San Andreas Fault, $20,000- Louie, Anderson, Brune, and Anooshehpoor NSF/SCEC: Simulation of Ground Motion in the Los Angeles Basin, Zeng, Anderson, $134,000. NSF: Kobe Ground Motions: Anderson, Zeng, Su, $134,600. NSF/SCEC: High Frequency Ground Motion, Anderson, Su, Zeng, $50,000. NSF/SCEC: Constraints on Source Parameters for Great Earthquakes Provided by Precarious Rocks Mojave Desert, Brune, Zeng, Anderson, $24,788.

13. Has this proposal been No submitted to any other agency for funding?

3 4 TABLE OF CONTENTS

Application for Federal Assistance, Standard Form (SF) 424...... 1 Proposal Information Summary...... 2 Table of Contents...... 3 Abstract...... 4 Budget Summary...... 5 Budget Explanation...... 6 Significance of Project...... 7 Introduction: Need for Site Characterization at Regional Network Stations...... 7 Proposed Work: Refraction Microtremor Array Studies of WGBSN Stations...... 9 References...... 11 Figures...... 12 Final Report and Dissemination of Results...... 15 Related Efforts...... 15 Project Personnel...... 15 Institutional Qualifications...... 19 Project Management Plan...... 20 Current Support and Pending Applications...... 20

5 ABSTRACT

This proposal is part of a systematic long-range vision that we have to develop a thorough understanding of the amplitudes of ground motions for the western Great Basin. Over the long range, our goal is the construction of a thoroughly justified model for strong motion, in which careful modeling of the physical phenomena compensates for the absence of abundant strong- motion data. The proposed work for this year deals with understanding the site response of our weak ground motion records. A weak-motion amplification model for each station will be one outcome, in addition to our major proposed emphasis on calibrating the site conditions at which the weak motion records are observed through measurement of the velocity of the rock beneath the station.

We propose to carry out shallow refraction and surface-wave microtremor studies at about two dozen high-dynamic range seismic network stations in the Western Great Basin Seismic Network (WGBSN) in Nevada and eastern California. The WGBSN includes the Reno and Las Vegas metropolitan areas, both of which are planned for intensive strong-motion recording efforts under the ANSS. This effort will help develop general characterization of rock sites, improved magnitude estimates, a regional attenuation relation, and "shake map" predicted instrumental acceleration capabilities for the Western Great Basin Seismic Network. With this project we will begin to calibrate site conditions for comparison with the standard NEHRP B-C boundary and other rock-site velocity models. We will employ a new and inexpensive method of deriving shear velocities to 100 m depths, that requires no seismic survey energy source or drilling, and only 2- 3 hours fieldwork at each site. The "refraction microtremor" method has proven to yield velocity profiles producing spectral amplifications that very closely matched amplifications predicted from a Rosrine borehole log in southern California. For greater efficiency, we propose to acquire a new seismic recording cable and lower-frequency geophones to increase survey efficiency and depth coverage. At hard-rock sites the method has also produced amplifications matching those of recorded weak motions. The proposed studies will improve our understanding of: (1) site conditions for rock sites in the Great Basin and perhaps in general; (2) the site conditions at seismic stations that will be needed to generate strength-of-shaking products in our network area; and (3) the accuracy and usability (by the public and public agencies) of earthquake magnitudes and "shake map" hazard notification products.

6 BUDGET SUMMARY

Project Title: Shear Velocities and Site Amplifications at Nevada and Eastern California Stations Needed for Instrumental Acceleration Mapping

Principal Investigators: John N. Louie, John G. Anderson

Proposed Start Date : Jan 1, 2002 Proposed Completion Date: Dec 31, 2002

COST CATEGORY Federal Federal Total First Year Second Year Both Years 1. Salaries and Wages $ 25,620 $ $

Total Salaries and Wages $ 25,620 2. Fringe Benefits/Labor Overhead $ 746 $ $

3. Equipment $ 4,600 $ $

4. Supplies $ 800 $ $

5. Services or Consultants $ $ $

6. Radiocarbon Dating Services $ $ $

7. Travel $ 5,500 $ $

8. Publication Costs $ 1000 $ $

9. Other Direct Costs $ 2755 $ $ 10. Total Direct Costs (items 1-9) $ 41,021 $ $ 11. Indirect cost / General and $ 15,357 $ $ Administrative (G&A) cost

12. Amount Proposed (items 10 & 11) $ 56,378 $ $

13. Total Project Cost (total of Federal $ 56,378 $ $ and non-Federal amounts)

7 BUDGET EXPLANATION 1/1/2002-12/31/2002 1. Salaries and Wages Principal Investigators: John N. Louie , 10 days @ $430/day $4,300 John G. Anderson , 5 days @ $700/day 3,500 Graduate Student Stipend Support: One summer term (3.0 mos. @ $2200/mo), 40 hrs/week 6,600 Two academic semesters (9.0 mos. @ $1100/mo), 20 hrs/week 9,900 Student Field Assistant Wages: 120 hours @ $11/hr (one for 15 days field assistance, 24 sites) 1,320

2. Fringe Benefits Louie @ 5% 215 Anderson @ 5% 175 Students @ 2% 356

3. Equipment: 200-meter 24-takeout refraction cable and 26 4.5-Hz geophones 4,600

4. Supplies: Miscellaneous field supplies, batteries, diskettes 800

5. Services or Consultants 0

6. Radiocarbon Age Dating 0

7. Travel Transportation Costs: 25 days University or commercial truck rental @ $70/day 1,750 25 days per diem for two @ $75/day/person 3,750

8. Publication Costs 10 pages in Seismological Research Letters (or similar journal) @ $100/page 1000

9. Other Direct Costs Misc. computer supplies and fees, for data analysis, modeling, and reporting 1000 Graduate student course fees (18 credits/year @ $97.50/credit) 1755

10. Total Direct Costs 41,021

8 11. Indirect Cost (44.3% of total direct costs less equipment and course fees: $34,666) 15,357

12. Amount Proposed $56,378

9 SIGNIFICANCE OF THE PROJECT

Introduction: Need for Site Characterization at Regional Network Stations

This proposal is part of a systematic long-range vision that we have to develop a thorough understanding of the amplitudes of ground motions for the western Great Basin. Over the long range, our goal is the construction of a thoroughly justified model for strong motion, in which careful modeling of the physical phenomena compensates for the absence of abundant strong-motion data. The proposed work for this year deals with understanding the site response of our weak ground motion records. A weak-motion amplification model for each station will be one outcome, in addition to our major proposed emphasis on calibrating the site conditions at which the weak motion records are observed through measurement of the velocity of the rock beneath the station.

We propose to measure shear velocities to 100 meters depth at two dozen sites of high-dynamic-range recording within the Western Great Basin Seismic Network (WGBSN), and to use these results together with records of small earthquakes from those stations to improve our understanding of site amplifications and attenuation in the western Great Basin. A new "refraction microtremor" technique (Louie, 2001) has proved through comparisons against borehole and microtremor array work to efficiently yield velocities with 85% accuracy. Applying this technique at newly upgraded stations within the WGBSN will address NEHRP elements I and II:

 ELEMENT I requests, for our region, Products for Earthquake Loss Reduction- "Compile new and upgrade existing data that provide input information for seismic hazard maps. Examples of the types of data include: moment-magnitude-based earthquake catalogs from regional network data… for earthquakes of magnitude 4 and greater in western North America… and regional or local information on attenuation properties or ground-motion amplification that would impact hazard assessments."

 ELEMENT II. A general theme is Research on Earthquake Occurrence and Effects– "Using data from our regional seismic networks, research in this area will address how complexities in the earthquake source, wave propagation effects, and near-surface geological deposits control the strong shaking." A specific element for our region is to “Develop regionally specific ground-motion time histories and validate them against observed ground-motion records.”

This project contributes to these elements by starting to deal with the issue of ground-motion amplification in a systematic way, and will lay the groundwork for future studies of detailed ground motion prediction including amplification in the heavily populated sedimentary basins. The ground motions at regional broadband stations will serve as our reference ground motions on “rock” when basin sites are observed. Ground-motion amplification due to shallow shear-velocity variations below the stations has an unknown effect on the seismograms, with the largest impact being at frequencies of ~1Hz and above (i.e. frequencies where magnitude is determined and where site response is important for engineering applications). It is well known that the general geology at a site is correlated with the response (e.g., Phillips and Aki, 1986; Su and Aki, 1995), but these studies were not able to use observed velocity structure at the stations. Indeed, in general and certainly in Nevada, the shallow velocity structure at network stations is not known. A sampling of such sites in southern California have shown 30-m- averaged shear velocities ranging from 462 to 1465 m/s (Louie, 2001; Abbott and Louie, 2000a; Abbott et al., 2001). Our objective is to understand the site conditions at the critical reference stations in western Nevada. The cost per site of this project is extremely low, about $2400.

10 The WGBSN is now recording calibrated seismograms from about two dozen high-dynamic-range network stations throughout western Nevada and eastern California (figure 1). These stations have been established or upgraded within the last four years to CMG-40 seismometers, recorded in real-time by on- site 24-bit RefTek acquisition systems. BRTT Antelope software in Reno merges these data with those from other instruments, picks, associates, distributes real-time event notices, archives seismograms and trades them with other networks, and facilitates off-line catalog development (figure 2). Although further improvements are eventually anticipated under the auspices of the Advanced National Seismic System (ANSS), the information to be collected under this project can thus be put to immediate use within the context of the present software and hardware.

We anticipate the following benefits of this project:

Earthquake-loss reduction– Prediction of strong shaking from our regional-network data requires the site characterization we propose here. In the western Great Basin, where damaging events are less frequent than in California, accurate prediction of possible shaking is key in convincing stakeholders to take action to reduce earthquake vulnerabilities. Spectral-ratio methods (Nakamura, 1989; Field and Jacob, 1995) applied to WGBSN records could begin to reveal the effects of near-surface deposits at the stations, and eventually at new urban ANSS strong-motion stations. However, the numbers of stations and events in the WGBSN is too small, and propagation distances are too great, to allow differentiation of site effects from source and path effects. Direct constraint of the site effects through velocity measurements will also allow comparison of "rock" versus "soil" sites later when we expect to be operating hundreds of urban strong-motion stations in Reno and Las Vegas. The station site characterizations proposed here will form an essential calibration, facilitating estimates of shaking and potential losses throughout our region.

Attenuation relations for the western Great Basin– There is very little constraint on amplitudes of strong ground motions in the western Great Basin. Thus it is difficult to directly determine an attenuation relation for our region. Spudich et al. (1999) have generated a relation for extensional regions worldwide that we can apply in our area. However, we believe that making use of the high-quality stations of the WGBSN that have now been available for a few years will allow, with the completion of several steps, a physics-based improvement over that method. We believe this will be helpful for effective promotion of earthquake-loss reduction measures in the region.

The velocity measurements proposed here, amounting to the site calibration of the WGBSN, will enable the construction of an attenuation curve for our region, from our own data. With calibration of site effects from this project, seismograms recorded from fewer, smaller, and more distant earthquakes may yield a more coherent attenuation curve than without calibration. Station site effects can be corrected, instead of having to be averaged over.

Characterization of rock-site response in Nevada and eastern California– Site classification from geological maps can yield large inconsistencies, especially in identifying "rock" or reference sites. In southern California, the refraction microtremor method has shown that supposed rock sites had 30-m- average shear velocities as low as 462 m/s in a tectonically shattered Precambrian anorthosite, and as high as 1465 m/s in a sparsely jointed Cretaceous granite (Louie, 2001; Abbott et al., 2001). This illustrates why there is only weak correlation of rock-site velocity to geologic age or rock type.

Spectral amplifications at "rock" sites can also be highly variable. Abbott and Louie (2000a) and Abbott et al. (2001) identified low-velocity surface soil layers only 5-10 m thick as the source of 4-8 Hz peaks in rock-site amplifications found from weak motion data. The only way to reliably control the spectral site 11 effect is thus to obtain a velocity profile (Steidl et al., 1996), as is proposed here. The refraction microtremor method (Louie, 2001) is well suited to the identification of shallow low-velocity layers.

Effect of unknown station site conditions on TriNet ShakeMaps– The instrumental acceleration maps currently being computed for southern California point out the need for site characterization at network stations. Figure 3a shows the TriNet peak instrumental-acceleration ShakeMap of southern California for the Oct. 1999 M7 Hector Mine earthquake. The white acceleration contours are extremely complex through the Mojave Desert region. The complexity reflects in large part the variations in predicted accelerations between rock in the mountain ranges and soil in the valleys.

Contours in figure 3a closing around stations, or forming "bulls-eye" patterns, point out unexpected variations in the measured instrumental accelerations among the stations. These variations are not predicted by a station's classification as a rock or soil site, nor by the attenuation relation used. Such problems are most apparent in the Mojave Desert region, where TriNet stations are relatively sparse. A Mojave location on the map cannot be influenced by the averaged data from several stations, but is dominated by the effect of one station. The simplest explanation for these variations in instrumental acceleration it a variation in site effects among the stations. We propose to measure these variations for the stations in the WGBSN that we plan to use in preparing ShakeMap-type notification products for Nevada and eastern California.

The fact that such variations appear most clearly on the peak acceleration ShakeMap, also suggests variations in shallow site shear velocities among the stations causes the complexity. The 3-second period spectral acceleration ShakeMap (figure 3b), however, also shows more unpredicted complexity than the other periods. We suggest for two TriNet stations that these errors are related to unaccounted velocity variations deeper than 30 m. The Indio station (A on figure 3b) sits atop very young and exceptionally deep sediments in Coachella Valley. The Baker station (B on figure 3b) may sit atop 30 m of soil, but is close to a high-velocity bedrock outcrop.

The refraction microtremor method used in the proposed project will be able to identify high-velocity rocks within 100 m of the surface (Louie, 2001). However, that method alone will not be able to assess the full depth of low-velocity deposits more than 100 m deep. For this reason, we restrict the proposed velocity measurements to WGBSN stations at known "rock" sites. Possible later measurements of strong- motion sites on deep soil in the region will have to take place in concert with gravity profiling and examination of borehole data, as Abbott and Louie (2000b) did for the Reno basin.

Proposed Work: Refraction Microtremor Array Studies of WGBSN Stations

We propose to measure shear velocity to 100 m depths at about two dozen stations of the Western Great Basin Seismic Network (WGBSN). The subject stations are the locations of high-dynamic-range real-time digital recording in our network area, covering much of Nevada, and parts of eastern California. We will make velocity measurements with a new "refraction microtremor" (ReMi) technique (Louie, 2001).

Refraction microtremor is a surface geophysical measurement of the apparent phase velocities of Rayleigh waves propagating along a linear, 200-m-long array of 24 compact geophones. The Rayleigh waves may arise locally or regionally from vehicle traffic, water waves, and wind shaking (Horike, 1985). Phase velocities are derived from multichannel microtremor records with the wavefield transformation of McMechan and Yedlin (1981). Analysis is rapid and automatic and does not require manual phase unwrapping as in SASW (Nazarian and Stokoe, 1984). The wavefield transformation does not involve

12 Fourier transforms in distance between array elements (as in Liu et al., 2000) and can recover very slow phase velocities from very shallow layers.

Relation to engineering standards– Because the ReMi technique can require as little as two person-hours to measure a site, and no active energy source, it offers a relatively inexpensive characterization of a large number of sites. Refraction microtremor can achieve the 85% velocity accuracy of surface shear-wave refraction surveys (when they are implemented according to ASTM standard D5777) at lower cost, Being a non-invasive surface technique, ReMi cannot achieve the depth resolution or 97% velocity accuracy of the ASTM standard for shear-velocity measurement, the crosshole seismic technique (ASTM D4428), of the OYO shear-velocity borehole logger (when implemented according to ASTM standard D5753), or of downhole shear-wave profiles. Only cone-penetrometer methods (ASTM D3441 and D5778) can match ReMi's low cost per site. Because cone penetrometers are limited to 20-m depths and relatively soft soil sites, they would not be appropriate for this project, to characterize rock sites.

Validation of the "refraction microtremor" characterization method– Figure 4 compares site characterizations at the Newhall Fire Station in southern California, a relatively deep soil site. The Rosrine project logged a borehole for P- and S-wave velocities to 107 m depth. Louie (2001) describes refraction-microtremor and P-wave refraction results from the site. The left side of figure 4 shows that a 4-layer shear-velocity model estimated from the microtremor Rayleigh phase-velocity data matches depth-averaged velocities from the borehole log to within 15% (85% accuracy).

The right side of figure 4 compares spectral amplifications of vertically propagating S waves at Newhall for the Rosrine downhole velocity log and for the results of the ReMi survey. The figure also shows the amplification predicted for the NEHRP B-C boundary model of Frankel et al. (1996). Amplifications were computed using a variation of the Haskell propagator matrix approach. The Rosrine log and the ReMi results predict similar spectral amplifications across the entire frequency band. Spectral peaks occur at similar frequencies, although the maximum values of the two highest peaks differ by about 10%. A mechanism contributing to the velocity and amplification differences is lateral heterogeneity. The borehole log is a point sample at one location, valid only within 2 m of the hole. The refraction microtremor survey was centered 3 m from the surface location of the borehole, but extended 100 m north and south from it. It thus produces more of a volume average of velocities across these relatively large distances. Despite the huge differences in subsurface volume sampling between the borehole log and the ReMi survey, the predicted amplifications of figure 4 do not differ substantially.

Figure 5 shows that the refraction microtremor technique has made shear-velocity measurements of similar 85% accuracy at many sites, across a huge range of velocities. The figure compares 30-m-depth- averaged shear velocities from ReMi against 30-m-averaged P-wave refraction velocities (adhering to ASTM D5777) at ten sites in Nevada, southern California, and New Zealand. The P- versus S-velocity comparison follows a 0.25 Poisson's ratio within 15% for all but one site, Seatoun (STN) in Wellington, New Zealand. The Seatoun site was a beach; none of the other sites were fully water-saturated to the surface.

Characterization of 24 sites of high-dynamic-range recording in Nevada and eastern California– We propose to carry out refraction microtremor surveys of shallow shear velocity at two dozen high-dynamic- range stations of the WGBSN. Figure 1 shows the locations in Nevada and eastern California of current stations with CMG-40 seismometers. At each of the two dozen sites we will record a 200-m-long ReMi array, and collect stacked hammer refraction records, as was done by Abbott et al. (2001) and Abbott and Louie (2000a) in southern California. In addition, we will record all data with not just one 24-channel linear array, but with two crossed arrays. The crossed arrays will allow better estimates of phase velocity from noise propagating in random directions across the arrays. Crossed-array recording will reign in the 13 high-velocity limits on the phase-velocity interpretations and more tightly constrain shear velocities, especially at 50-100 m depths. Experience at rural, very quiet rock sites in the Mojave Desert suggests that these additional constraints will be needed at many of the WGBSN CMG-40 sites, which are very isolated. The P-wave refraction velocity interpretations will also benefit from these minimal constraints on lateral velocity variations.

Increasing the efficiency of ReMi surveys– Measurements at each site will take about a half-day of field time by a crew of two people. (In this proposal’s budget, we are allowing one day per station to allow for travel times.) To reach this level of productivity, we propose to acquire $4,600 of new equipment for the project. The equipment includes a new set of lighter, more portable refraction cables suitable for deployment by one person. Our current refraction cables are not segmented, with one 24-channel cable being 360 m long and weighing more than 40 kg. It must be deployed by a crew of three, with layout and pickup occupying 3 person-hours. Acquiring a lighter, segmented 200-m-long 24-channel cable should reduce the need for cable handling to a total of one person-hour per array.

We propose 25 field days for measuring all two-dozen stations because of the large distances between most of them. The WGBSN is very sparse, and the high-dynamic-range stations are distributed around a huge region of Nevada and eastern California almost 1000 km across. Further, many stations are in extremely isolated locations, requiring hours of driving on jeep trails to reach them.

Louie (2001) showed that the depth coverage of the refraction microtremor technique is closely related to the low-frequency response capabilities of the geophones employed. Most of the sites described in Louie (2001) were measured with geophones having resonance at 8-12 Hz, and yielded velocities to 100-m depths. One site received a repeat survey with 4.5-Hz geophones, and yielded good velocity constraints to more than 150 m depth. We propose to acquire 25 4.5-Hz compact vertical geophones, thus extending the depth capabilities of this project. These geophones will not take any more field effort to install or pick up at each site.

Data analysis and modeling– We will analyze the refraction microtremor records from all sites with the wavefield transformation method as described in Louie (2001), combining the different array directions at each site into the interpretations. After picking phase velocities and their extreme limits, we will model both "best-fit" and high- and low-velocity extremal models as we did for Newhall in figure 4. The refraction times and P-wave velocities we will use for constraint on the shear-wave velocities and on modeling the Rayleigh-wave dispersion curves.

The range of velocity models developed in fitting dispersion curves we will complement by a simple quarter-wavelength travel-time velocity analysis, as in Brown (1998). At each site we will research other available information on site geological structure, e.g., talking with local landowners about water-well depths, and investigating any information available from local construction companies that may have done engineering studies near the sites. Some WGBSN stations are near extensively built-up radio tower sites or communications outpost buildings carefully engineered against poor mountaintop weather conditions. From all the velocity models we will then compute spectral amplifications at each site for comparison with the NEHRP B-C boundary model (Frankel et al., 1996) and the rock-site model of Steidl et al. (1996).

We propose as well to assemble seismograms from each site, out of our archives, to derive spectral amplification curves from weak-motion records. As done by Abbott and Louie (2000a) and Abbott et al. (2001) for southern California sites, we will estimate amplifications using both single-site (Nakamura, 1989; Field and Jacob, 1995) and multi-site (Steidl et al., 1996) spectral ratios. We will present to the seismological community at the end of the project a comparison of amplifications derived from site 14 characterizations against those from weak-motion spectral ratios. This comparison will also address the properties of rock sites in general, as we will be able to add results from the Mojave Desert rock sites characterized by Abbott et al. (2001), as well as on-going characterization work at sites such as the Piñon Flat Observatory funded by SCEC.

References

Abbott, R. E., and Louie, J. N., 2000a, High shear wave velocities under precarious rock sites might be enough to explain their existence near the San Andreas fault: presented at Amer. Geophys. Union Fall Mtg., Dec. 15-19, San Francisco. Abbott, R. E., and Louie, J. N., 2000b, Depth to bedrock using gravimetry in the Reno and Carson City, Nevada area basins: Geophysics, 65, 340-350. Abbott, R. E., Louie, J. N., Brune, J. N., and Anooshehpoor, R., 2001, Analysis of shallow site response to LARSE-2 blasts at precarious rock sites near the San Andreas fault: unpub. final project report to the Southern California Earthquake Center, March 10, 21 pp. (Available electronically from http://www.seismo.unr.edu/ftp/pub/louie/larse/final/louie-final00.htm). Boore, D. M., and L. T. Brown, 1998, Comparing shear-wave velocity profiles from inversion of surface- wave phase velocities with downhole measurements; systematic differences between the CXW method and downhole measurements at six USC strong-motion sites: Seismol. Res. Lett., 69, 222- 229. Brown, L. T., 1998, Comparison of Vs profiles from SASW and borehole measurements at strong motion sites in southern California: M.Sc. Eng. Thesis, University of Texas at Austin, 349 pp. Field, E. H., and Jacob, K. H., 1995, A comparison and test of various site-response estimation techniques, including three that are not reference-site dependent, Bull. Seismol. Soc. Amer., 85, 1127-1143. Frankel, A. D., C. S. Mueller, T. P. Barnhard, D. M. Perkins, E. V. Leyendecker, N. Dickman, S. L. Hanson, and M. G. Hopper, 1996, National seismic-hazard maps: documentation June 1996, pp. 110, U. S. Geological Survey, Reston. Horike, M., 1985, Inversion of phase velocity of long-period microtremors to the S-wave-velocity structure down to the basement in urbanized areas, J. Phys. Earth., 33, 59-96. Iwata, T., Kawase, H., Satoh, T., Kakehi, Y., Irikura, K., Louie, J. N., Abbott, R. E., and Anderson, J. G., 1998, Array Microtremor Measurements at Reno, Nevada, USA: presented at Amer. Geophys. Union. Fall Mtg., Dec. 6-10, San Francisco. Liu, H. P., Boore, D. M., Joyner, W. B., Oppenheimer, D. H., Warrick, R. E., Zhang, W., Hamilton, J. C., and Brown, L. T, 2000, Comparison of phase velocities from array measurements of Rayleigh waves associated with microtremor and results calculated from borehole shear-wave velocity profiles: Bull. Seismol. Soc. Amer., 90, 666-678. Louie, J. N., 2001, Faster, better: shear-wave velocity to 100 meters depth from refraction microtremor arrays: Bull. Seismol. Soc. Amer., 91, no. 2 (April), 347-364. (Available electronically from http://www.seismo.unr.edu/vs/refr.html). McMechan, G. A., and Yedlin, M. J., 1981, Analysis of dispersive waves by wave field transformation: Geophysics, 46, 869-874. Nakamura, Y., 1989, A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface, QR Railway Technical Research Institute, 30, 1. Nazarian, S., and Stokoe II, K. H., 1984, In situ shear wave velocities from spectral analysis of surface waves: Proceedings of the World Conference on Earthquake Engineering, 8, San Francisco, Calif., July 21-28.

15 Phillips, W. S., and Aki, K., 1986, Site amplification of coda waves from local earthquakes in central California: Bull. Seismol. Soc. Amer., 76, 627-648. Spudich, P., Joyner, W. B., Lindh, A. G., Boore, D. M., Margaris, B. M., and Fletcher, J. B., 1999, SEA99: a revised ground motion prediction relation for use in extensional tectonic regimes: Bull. Seismol. Soc. Amer., 89, 1156-1170. Steidl, J. H., A. G. Tumarkin, and R. J. Archuleta, 1996, What is a reference site?: Bull. Seismol. Soc. Amer., 86, 1733-1748. Su, F., and Aki, K., 1995, Site amplification factors in central and southern California determined from coda waves: Bull. Seismol. Soc. Amer., 85, 452-465.

16 17 18 19 FINAL REPORT AND DISSEMINATION OF RESULTS

All reports requested and required by the USGS will be submitted in a prompt and timely manner and the results of the research will be published in a professional journal.

RELATED EFFORTS

Dr. Louie has extensive experience with multi-channel seismic analysis methods (see vita) and is currently involved in research projects to study shallow site response at precarious rock sites near the San Andreas fault, and seismic hazard in the vicinity of Las Vegas and Reno (see current support). Dr. Anderson has extensive experience in the analysis of site response and the computation of synthetic time- histories (see vita), and is currently involved in research projects similar to this in California, Nevada, Mexico, Turkey, and Taiwan (see current support).

PROJECT PERSONNEL

This study will be conducted jointly by principal investigator John Louie, Associate Professor of Seismology, and co-investigator John G. Anderson, Professor of Geophysics, at the Nevada Seismological Laboratory.

20 John N. Louie

Seismological Laboratory 174, Mackay School of Mines The University of Nevada, Reno, NV 89557-0141 (775) 784-4219; fax (775) 784-1833; [email protected]

Professional Experience Associate Professor of Seismology, Seismological Laboratory, The University of Nevada, Reno; since January 1992. Responsibilities include undergraduate and graduate instruction, supervision of M.S. and Ph.D. degree candidates, and conducting a research program in seismology. Assistant Professor of Geosciences, The Pennsylvania State University, University Park, Pennsylvania; Sept. 1987 to Jan. 1992. Responsibilities included undergraduate and graduate instruction, supervision of M.S. and Ph.D. degree candidates, and research in high-resolution seismology.

Relevant Publications J. N. Louie, 2001, Faster, better: shear-wave velocity to 100 meters depth from refraction microtremor arrays: Bull. Seismol. Soc. Amer., 91, no. 2 (April), 347-364. (Available electronically from http://www.seismo.unr.edu/vs/refr.html). R. E. Abbott, J. N. Louie, S. J. Caskey, and S. Pullammanappallil, 2001, Geophysical confirmation of low-angle normal slip on the historically active Dixie Valley fault, Nevada: Jour. Geophys. Res., 106, 4169-4181. R. E. Abbott and J. N. Louie, 2000, Depth to bedrock using gravimetry in the Reno and Carson City, Nevada basins: Geophysics, 65, 340-350. A. M. Asad, S. K. Pullammanappallil, A. Anooshehpoor, and J. N. Louie, 1999, Inversion of travel data for earthquake locations and three-dimensional velocity structure in the Eureka Valley area, eastern California: Bull. Seismol. Soc. Amer., 89, 796-810. G. Shields, K. Allander, R. Brigham, R. Crosbie, L. Trimble, M. Sleeman, R. Tucker, H. Zhan and J. N. Louie, 1998, Geophysical surveys of an active fault: results from Pahrump Valley, California- Nevada border: Bull. Seismol. Soc. Amer., 88, 270-275.

Other Important Publications S. K. Pullammanappallil and J. N. Louie, 1994, A generalized simulated-annealing optimization for inversion of first-arrival times: Bull. Seismol. Soc. Amer., 84, 1397-1409. J. N. Louie, S. K. Pullammanappallil, and W. Honjas, 1997, Velocity models for the highly extended crust of Death Valley, California: Geophys. Res. Lett., 24, 735-738. S. Chavez-Perez and J. N. Louie, 1998, Crustal imaging in southern California using earthquake sequences: Tectonophysics, 286 (March 15), 223-236. S. Chavez-Perez, J. N. Louie, and S. K. Pullammanappallil, 1998, Seismic depth imaging of normal faulting in the southern Death Valley basin: Geophysics, 63, 223-230. Z. Kanbur, J. N. Louie, S. Chavez-Perez, G. Plank, and D. Morey, 2000, Seismic reflection study of Upheaval Dome, Canyonlands National Park, Utah: Jour. Geophys. Res. (Planets), 105, 9489- 9505.

Graduate Education California Institute of Technology, Pasadena, California. Degrees: Ph.D. Geophysics, June, 1987; M.S. Geophysics, June, 1983.

21 John G. Anderson Seismological Laboratory, MS 174, University of Nevada, Reno, Nevada 89557 Phone: (702) 784-4265 Fax: (702) 784-1833 Email: [email protected]

Education Ph.D. Geophysics, 1976 Columbia University, New York City, New York B. S. Physics, 1970 Michigan State University, East Lansing, Michigan Diploma 1966 LaSalle High School, Niagara Falls, New York

Professional Experience University of Nevada, Reno - Mackay School of Mines Department of Geological Sciences Professor of Geophysics: July 1992 - present Associate Professor of Geophysics: Sept. 1988 - June 1992 Seismological Laboratory Associate Director: Sept. 1989 - present Acting Director: June 1994 - Dec. 1995 University of California, San Diego Institute of Geophysics and Planetary Physics Associate Research Geophysicist and Lecturer: July 1984 to 30 June 1990 Assistant Research Geophysicist: August 1980 to 1984 Department of Applied Mechanics and Engineering Sciences Associate Research Engineer: July 1984 to 30 June 1988 Assistant Research Engineer: August 1980 to 1984 University of Southern California, Los Angeles Senior Research Associate: Oct. 1978 to 1980 Research Associate: October 1976 to 1978 California Institute of Technology, Pasadena, California Research Fellow: November 1975 to 1976. Lamont Doherty Geological Observatory of Columbia University, Palisades, N. Y. Research Assistant: July 1970 to 1975.

Other Experience Nevada Seismic Safety Council Chairman, November 1992 - November, 1997 Member, May 1992 - present Bulletin of the Seismological Society of America Associate Editor, Sept 1992 - 1994 National Academy of Sciences Committee on Seismic Base Isolation 1989-1993 Committee on Probabilistic Seismic Hazard Analysis 1984-1988

Major Research Interests Engineering seismology: all aspects , including applications of geological and seismological information to estimate seismicity and seismic hazards; recording strong ground motions; understanding the physics of near-source ground motions; applications to engineering problems.

Anderson, J. G. and S. Hough (1984). A Model for the shape of the Fourier amplitude spectrum of acceleration at high frequencies: Bull. Seism. Soc. Am. 74, 1969-1994. Anderson, J. G., P. Bodin, J. Brune, J. Prince, S. Singh, R. Quaas, M. Onate, and E. Mena, (1986). Strong ground motion and source mechanism of the Mexico earthquake of Sept. 19, 1985, Science 233, 1043-1049. Anderson, J. G. (1991). Strong Motion Seismology, Reviews of Geophysics, Seismology Supplement, U. S. National Report to the International Union of Geology and Geophysics 1987-1990, 700-720. 22 Yu, G., J. G. Anderson and R. Siddharthan (1993). On the characteristics of nonlinear soil response, Bull. Seism. Soc. Am. 83, 218-244. Zeng, Y., J. G. Anderson and G. Yu (1994). A composite source model for computing realistic synthetic strong ground motions, Geophysical Research Letters 21, 725-728. Anderson, J. G. and G. Yu (1996). Predictability of strong motions from the Northridge, California, earthquake, BSSA 86, S100-S114. Anderson, J. G., S. G. Wesnousky, and M. W. Stirling (1996). Earthquake size as a function of fault slip rate, Bull. Seism. Soc. Am. 86, 683-690. Anderson, J. G. (1997). Benefits of scenario ground motion maps, Engineering Geology 48, 43-57. Anderson, J. G. (1997). Seismic energy and stress drop parameters for a composite source model, Bulletin of the Seismological Society of America 87, 85-96. Anderson, J. G. and J. N. Brune (1999). Methodology for using precarious rocks in Nevada to test seismic hazard models, Bull. Seism. Soc. Am 89, 456-467. Anderson, J. G. and J. N. Brune (1999). Probabilistic seismic hazard analysis without the ergodic assumption, Seismological Research Letters 70, 19-28.

Major Synergistic Activities Director of Nevada Seismological Laboratory, studies on related types of projects in the Great Basin of the United States.

Collaborators for the Past Four Years The following is a list of coauthors on papers with John Anderson since 1996.

L. Alcantara, S. Alcocer, R. Anooshehpoor, J. D. Bray, L. F. Bonilla, J. N. Brune, C. Cramer, J. Cuenca, S. Day, C. dePolo, D. dePolo, P. P. Dimitriu, W. Elgemal, J. M. Espinosa, E. H. Field, G. A. Ichinose, P. A. Johnson, A. Jimenez, C. Javier, J. Keaton, S. Kramer, M. Lahren, Y. Lee, J. Lermo, B. Lopez, N. Matasovic, R. Meli, E. Mena, S.-D. Ni, M. Ordaz, J. Price, C. Roblee, R. Quaas, M. Rodriguez, Kenji Satake, R. Schweickert, F. Sanchez-Sesma, M. W. Stirling, R. Siddharthan, S. K. Singh, Kenneth D. Smith, Feng Su, Haluk Sucuoglu, D. J. Wald, S. G. Wesnousky, G. Yu, Y. Zeng

Students and Post-Docs S. Hough, R. Castro, C. dePolo, Gene A. Ichinose, Y. Lee, S.-D. Ni, M. W. Stirling, Feng Su, G. Yu, Y. Zeng

Graduate and Post-Doctoral Advisor PhD. Advisor: Paul Richards Postdoctoral Advisor: M. D. Trifunac

23 INSTITUTIONAL QUALIFICATIONS

As one of the statewide research agencies of the University of Nevada, the Seismological Research Laboratory is headed by a Director (J. Anderson) who reports to the Dean, Mackay School of Mines. The current research staff consists of ten professional seismologists. Other professionals include a Research and Design Engineer. Technical staff members include two seismographic technicians, one record analyst, 1.5 FTE of computer support personnel, and five graduate research assistants. The Seismological Laboratory operates the Western Great Basin Seismic Network (USGS Funding; digital upgrades provided by the W.M. Keck Foundation), the Yucca Mountain Digital Seismic Network (DOE- HRC Funding). These networks now include more than three dozen state-of-the-art high-dynamic-range real-time digital stations. After twelve years of operation of computer-based digital seismic acquisition, over 50,000 local events have been located, and these and many more regional and teleseismic events and blasts have been archived, leading to over 600,000 digital seismograms archived on magnetic tape and CD-ROM. Data bases from paper records and other analog sources extend back to 1916 (e.g. a collection of Wiechert smoked-paper recordings). Earthquake data are now manipulated using the Antelope and CSS database systems developed by BRTT, allowing us to interchange both real-time and archived catalog and seismogram data with the SCSN, NCSN, Oregon, Arizona, and Utah seismic network through data centers at Caltech, Menlo Park, and Salt Lake City. Computer hardware consists of four Sun servers and twenty Sun workstations with speeds up to 400 MHz, eight Pentium II and III UNIX workstations, and numerous PCs and Macintoshes. These processors are used mainly for research applications and provide a basis for analysis of the accumulating network data base. One of the servers hosts the Lab's web site at www.seismo.unr.edu, which at 30,000- 80,000 hits per week is one of the University's most popular public outreach programs. Seismic reflection data sets are processed both with John Louie's ``Resource Geology'' UNIX system for research, and with the industry-standard Halliburton ProMAX system. In partnership with the Nevada Applied Research Initiative and OptimSoftware.com, the Lab operates a 16 Gflop Beowulf parallel processor. Additional equipment is available for field work and special investigations. The seismology group has 15 portable Reftek seismographs and 8 PRS-4 portable digital seismographs. We have 18 Mark Products L-4 1-second, three sets of Kinemetrics 5-second, 10 sets of 1-Hz S13 and several Guralp CMG- 5 and CMG-4 broadband seismometers. The W. M. Keck Foundation donated to the Mackay School of Mines (of which the Seismological Lab is a part) a 48-channel, Pentium-based Bison Galileo-21 reflection-refraction recording system, with 700 m cables for 8-Hz refraction geophones; and a high- resolution 210 m segmented roll-along cable with 48 groups of six 100-Hz geophones each. The School maintains as well a Lacoste and Romberg Model G gravimeter with 0.04 mGal demonstrated precision, and three Trimble 4000SSi, dual-frequency, carrier-phase, geodetic GPS receivers. A grant from the W. M. Keck Foundation also established four years ago the Mapping, Modeling, and Visualization (MMV) Laboratory in the Mackay School of Mines. It consists of 10 PCs and workstations served by a Silicon Graphics multiprocessing supercomputer, with every major GIS, image- processing, geophysical, and geological software package available on multiple platforms. The School is wired for 100 Mbps full-duplex ethernet, with high-speed isolated connections available to all servers. All buildings on campus connect via a 100 Mbps campus fiber network, which has a fiber connection at 155 Mbps to the nearest CALREN/vBNS/Abilene gigaPoP at U.C. Davis.

24 PROJECT MANAGEMENT PLAN

The project is projected to last one year. Dr. John Louie will be supervising the refraction and noise experiments, in close consultation with Dr. John Anderson. All Pis are at the Seismological Laboratory, University of Nevada, Reno. They will be responsible for the completion of the project and submittal of required reports.

CURRENT AND PENDING GRANT SUPPORT

John N. Louie

Current: U.S. Geological Survey/NEHRP: Seismic Hazards in the Vicinity of Las Vegas and Reno, $100,000, 4/1/1999 - 9/30/2001, Anderson, Zeng, Su, and Louie (0.5 summer month). National Science Foundation/SCEC: Analysis of Shallow Site Response to LARSE-2 Blasts at Precarious Rock Sites Near the San Andreas Fault, $10,270, 4/01/2000 - 3/31/2001, Louie (0.15 summer month), Brune, Anooshehpoor. National Science Foundation/Tectonics: Evolution of the Sierra Nevada - Basin and Range Boundary — Tephrochronologic and Gravity Constraints on the Record in Neogene Basin Deposits, $55,182, 6/1/2000 - 5/30/2002, Cashman, Louie (0.25 summer month), Trexler. National Science Foundation/SCEC: Site Response Investigations at Critical Precarious Rocks Near the San Andreas Fault, $20,000, 4/01/2001 - 3/31/2002, Louie (0.5 summer month), Anderson, Brune, Anooshehpoor.

Pending: National Science Foundation: ITR/AP(Geo): Speed and accuracy of 3-d traveltime computation on Beowulf supercomputers: adaptive parallelization and tomographic applications, $480,585 9/1/2001 - 8/31/2003, Louie (1.0 summer month/year), Kongmunvattana. National Science Foundation: ITR/AP(Geo): Factual Geologic Mapping: The development of field tools using GIS and remote sensing to produce quantified geological maps, $371,178 9/1/2001 - 8/31/2003, Sawatzky, Taranik, Louie (0.5 summer month/year). U.S. Geological Survey/NEHRP: Shear Velocities and Site Amplifications at Nevada and Eastern California Stations Needed for Instrumental Acceleration Mapping, $56,378 1/1/2002- 12/31/2002, Louie (0.5 month), Anderson. U.S. Geological Survey/NEHRP: Shallow Velocity Structures and Site Effects at Precarious Rock Sites Critical to Southern California Seismic Hazard, $49,403 1/1/2002-12/31/2002, Louie (0.5 month), Brune, Anooshehpoor.

25 CURRENT AND PENDING GRANT SUPPORT John G. Anderson

CURRENT: NSF/SCEC: Simulation of Ground Motion in the Los Angeles Basin, Zeng, Anderson, 2/1/95-1/31/02, $134,000, 0 days. NSF: Kobe Ground Motions: Anderson, Zeng, Su, 8/15/97-7/31/01, $134,600, 10 days, none in 2001. NSF/SCEC: High Frequency Ground Motion, Anderson, Su, Zeng, 2/1/98-1/31/02, $50,000, 5 days. NSF/SCEC: Constraints on Source Parameters for Great Earthquakes Provided by Precarious Rocks Mojave Desert, Brune, Zeng, Anderson, 2/1/99-1/31/02, $24,788, 5 days. Berkeley: Joint UNR-UC Berkeley Proposal to Cal Trans, Anderson, Smith, Louie, 1/1/00-12/31/02, $27,273, 0 days. NSF/USC: Stochastic Broadband Ground Motion Estimation Workshop and Legacy Document Development, Zeng, Anderson, 7/1/00-1/31/02, $25,000. Berkeley: Validation of 1-D Numerical Simulation Procedures, Zeng, Anderson, 5/1/00-8/30/01, $50,000, 5 days. UCB/PEER/PG&E: Input Motions for Earthquake Simulator Testing of Electric Substation Equipment, Anderson, Su, Zeng, 5/1/00-4/30/01, $40,000, 5 days. DOI/USGS: Earthquake Research n Eastern California and Western Nevada, Anderson, 11/1/00- 10/31/01, $45,000, 0 days. DOMVPS/EMD: Earthquake Risk Mitigation, C. dePolo, J. Price, J. Anderson, D. dePolo, 10/1/00- 9/30/01, no salary. DOI/USGS: Site Response of the Chi-Chi Taiwan Earthquake, Zeng, Su, Anderson, 2/1/01-1/31/02, $40,000, 2 days. North Atlantic Treaty Organization: Strong Motion and Seismic Network in Turkey, Anderson, 2/1/01- 1/31/04, $65,000, no salary.

PENDING: NSF: Continued Operation of the Guerrero Accelerograph, 1/1/01-1/1/04, $350,930, 1 month/year. NSF: Failure of the Seismic Moment vs. Fault Slip Formula for Thrust Earthquakes Study of Implications for Seismic Hazard and “Tsunami Earthquakes,” 6/1/01-5/31/02, USGS/DOI/NEHRP: Interpretation of Precarious Rock and Overturned Transformer Evidence for Ground Shaking in the M=7.6 Arvin-Tehachapi Earthquake, and Analog for Disastrous Shaking from a Major Thrust Fault in the Los Angeles Basin, J. Brune, R. Anooshehpoor, Y. Zeng, J. Anderson, 1/1/02-12/31/02, $81,631, 5 days. USGS/DOI/NEHRP: Development of Ground Motion Regression Relations for Eastern North America, Y. Zeng, F. Su, J. Anderson, 1/1/01-12/31/02, $56,584, 5 days. USGS/DOI/NEHRP: Seismic Hazard in the Vicinity of Reno, Nevada, J. Anderson, F. Su, 2/1/02- 1/31/03,$88,762, 20 days. USGS/DOI/NEHRP: Shear Velocities and Site Amplification at Nevada and Eastern California Stations Needed for Instrumental Acceleration Mapping, J. Louie, J. Anderson, 1/1/02- 12/31/02,$49,403, 5days.