Publications
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Instrumental intensity distribution for the Hector Mine, California, and the Chi-Chi, Taiwan, earthquakes: Comparison of two methods
We compare two methods of seismic-intensity estimation from ground-motion records for the two recent strong earthquakes: the 1999 (M 7.1) Hector Mine, California, and the 1999 (M 7.6) Chi-Chi, Taiwan. The first technique utilizes the peak ground acceleration (PGA) and velocity (PGV), and it is used for rapid generation of the instrumental intensity map in California. The other method is based on t
Authors
V. Sokolov, D. J. Wald
Fault structure and mechanics of the Hayward Fault, California from double-difference earthquake locations
The relationship between small-magnitude seismicity and large-scale crustal faulting along the Hayward Fault, California, is investigated using a double-difference (DD) earthquake location algorithm. We used the DD method to determine high-resolution hypocenter locations of the seismicity that occurred between 1967 and 1998. The DD technique incorporates catalog travel time data and relative P and
Authors
Felix Waldhause, William L. Ellsworth
Fault structure and kinematics of the Long Valley Caldera region, California, revealed by high-accuracy earthquake hypocenters and focal mechanism stress inversions
We have determined high-resolution hypocenters for 45,000+ earthquakes that occurred between 1980 and 2000 in the Long Valley caldera area using a double-difference earthquake location algorithm and routinely determined arrival times. The locations reveal numerous discrete fault planes in the southern caldera and adjacent Sierra Nevada block (SNB). Intracaldera faults include a series of east/west
Authors
Stephanie Prejean, William L. Ellsworth, Mark Zoback, Felix Waldhauser
Paleoseismic event dating and the conditional probability of large earthquakes on the southern San Andreas fault, California
We introduce a quantitative approach to paleoearthquake dating and apply it to paleoseismic data from the Wrightwood and Pallett Creek sites on the southern San Andreas fault. We illustrate how stratigraphic ordering, sedimentological, and historical data can be used quantitatively in the process of estimating earthquake ages. Calibrated radiocarbon age distributions are used directly from layer d
Authors
G. P. Biasi, R.J. Weldon, T. E. Fumal, G. G. Seitz
A record of large earthquakes on the southern Hayward fault for the past 500 years
The Hayward fault, a major branch of the right-lateral San Andreas fault system, traverses the densely populated eastern San Francisco Bay region, California. We conducted a paleoseismic investigation to better understand the Hayward fault's past earthquake behavior. The site is near the south end of Tyson's Lagoon, a sag pond formed in a right step of the fault in Fremont. Because the Hayward fau
Authors
J. J. Lienkaemper, T. E. Dawson, S. F. Personius, G. G. Seitz, L.M. Reidy, D. P. Schwartz
Spatial and temporal deformation along the northern San Jacinto fault, southern California: Implications for slip rates
The San Timoteo badlands is an area of uplift and erosional dissection that has formed as a result of late Quaternary uplift along a restraining bend in the San Jacinto fault, of the San Andreas fault system in southern California. This bend currently is located in a region where late Quaternary deposits and associated surfaces have formed in lower San Timoteo Canyon. We have used morphometric ana
Authors
K.J. Kendrick, D. M. Morton, S. G. Wells, R. W. Simpson
Geomorphic studies of landslides in the Tully Valley, New York: Implications for public policy and planning
On April 27, 1993, a large landslide in the Tully Valley, Onondaga County, NY, destroyed three houses and resulted in the evacuation of four others; it also triggered a loss of potable drinking water for about 15 homes north of the slide area and affected a total of 20 ha of land. In the 7 years following this slide, several studies have been conducted by federal and state environmental agencies a
Authors
D. L. Pair, W. M. Kappel
High-resolution image of Calaveras Fault seismicity
By measuring relative earthquake arrival times using waveform cross correlation and locating earthquakes using the double difference technique, we are able to reduce hypocentral errors by 1 to 2 orders of magnitude over routine locations for nearly 8000 events along a 35-km section of the Calaveras Fault. This represents ∼92% of all seismicity since 1984 and includes the rupture zone of the M 6.2
Authors
D. P. Schaff, G. H. R. Bokelmann, G. C. Beroza, Felix Waldhause, William L. Ellsworth
Comparing landslide inventories: The map depends on the method
Landslide inventory maps are generally prepared by interpreting the geomorphic expression of landsliding on aerial photos, topographic maps, or on the ground. Distinctive landslide geomorphology allows the recognition and mapping of landslides, although there are always landslides that have very subtle expression and are not identified. The difficulties of mapping landslides based on their geomorp
Authors
C.J. Wills, T.P. McCrink
Remotely sensed geology from lander-based to orbital perspectives: Results of FIDO rover May 2000 field tests
Blind field tests of the Field Integration Design and Operations (FIDO) prototype Mars rover were carried out 7-16 May 2000. A Core Operations Team (COT), sequestered at the Jet Propulsion Laboratory without knowledge of test site location, prepared command sequences and interpreted data acquired by the rover. Instrument sensors included a stereo panoramic camera, navigational and hazard-avoidance
Authors
B. Jolliff, A. Knoll, R.V. Morris, J. Moersch, H. McSween, M. Gilmore, R. Arvidson, R. Greeley, Kenneth E. Herkenhoff, S. Squyres
Revised ages for tuffs of the Yellowstone Plateau volcanic field: Assignment of the Huckleberry Ridge Tuff to a new geomagnetic polarity event
40Ar/39Ar ages were determined on the three major ash-flow tuffs of the Yellowstone Plateau volcanic field in the region of Yellowstone National Park in order to improve the precision of previously determined ages. Total-fusion and incremental- heating ages of sanidine yielded the following mean ages: Huckleberry Ridge Tuff—2.059 ± 0.004 Ma; Mesa Falls Tuff— 1.285 ± 0.004 Ma; and Lava Creek Tuff—
Authors
M. A. Lanphere, D. E. Champion, R. L. Christiansen, G. A. Izett, J.D. Obradovich
Study on 3-D velocity structure of crust and upper mantle in Sichuan-yunnan region, China
Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone ex
Authors
C. Wang, Walter D. Mooney, X. Wang, J. Wu, H. Lou, F. Wang