Steven Neal Ward

Present Position:

Research Geophysicist

Institute of Geophysics and Planetary Physics

University of California

Santa Cruz, CA 95064

(831) 459-2480 email: ward@es.ucsc.edu

Education:

B.S., Physics, 1974 Bucknell University, Lewisburg, Pennsylvania

M.A., Geophysics, 1976 Princeton University, Princeton, New Jersey

Ph.D., Geophysics, 1978 Princeton University, Princeton, New Jersey

Experience:

7/86-Present Research Geophysicist

1/84-6/86 Associate Research Geophysicist

University of California, Santa Cruz

10/80-12/83 Associate Research Geophysicist

Harvard University

9/78-9/80 Postgraduate Research Geophysicist

Scripps Institution of Oceanography

9/74-8/78 Assistant in Research (Geophysics)

Assistant in Instruction (Oceanography)

Princeton University

Service:

1992-2003. Board of Editors Geophysical Journal International

1990. Guest Co-Editor for the Geophysical Research Letters special issue on the 1989, Loma Prieta Earthquake.

Research Interests:

-Theoretical Seismology/Seismic Sources

-Tsunami Wave Generation/ Asteroids, Landslides, Earthquakes

-Extraction of Earthquake Source Parameters from

Seismograms and Geodetic Data

-Plate Boundary Interactions

-Neotectonics

-Earthquake Hazard

-Impact Cratering

 

Publications:

Ward, S. N., 1978. Two studies of long period body waves. Ph.D. thesis, Princeton University.

Ward, S. N., 1979. Long period reflected and converted upper mantle phases. Bull. Seism. Soc. Am., 68, 133-153.

Ward, S. N., 1979. Ringing P waves and submarine faulting, J. Geophys. Res., 84, 3057-3062.

Ward, S. N., 1980. Body wave calculations using moment tensor sources in spherically symmetric, inhomogeneous media, Geophys. J. Roy. Astron. Soc., 60, 53-66.

Ward, S. N., 1980. A technique for the recovery of the seismic moment tensor applied to the Oaxaca, Mexico earthquake of November 1978, Bull. Seism. Soc. Am., 70, 717-734.

Ward, S. N., 1980. Relationships of tsunami generation and an earthquake source, J. Phys. Earth, 28, 441-474.

Ward, S. N., 1981. On elastic wave calculations in a sphere using moment tensor sources, Geophys. J. Roy. Astron. Soc., 66, 23-30.

Ward, S. N., 1981. On tsunami nucleation: I. A point source, J. Geophys. Res.,86, 7895-7900.

Ward, S. N., 1981. Simplified bodywave source terms with one application in moment tensor recovery, in Identification of seismic sources - Earthquakes or underground explosion, ed. E. S. Husebye and S. Mykkeltveit, p. 269-272, D. Reidel Publishers, Boston.

Ward, S. N., 1982. On tsunami nucleation: II. An instantaneous modulated line source, Phys. Earth Planet. Int., 27, 273-285.

Ward, S. N., 1982. Earthquake mechanisms and tsunami generation-- The Kurile Islands event of October 13, 1963, Bull. Seism. Soc. Am., 72, 759-777.

Ward, S. N., 1983. Body wave inversion: Moment tensors and depths of oceanic intraplate bending earthquakes, J. Geophys. Res., 88, 9315-9330.

Ward, S. N., 1984. A note on lithospheric bending calculations, Geophys. J. Roy. Astron. Soc., 78, 241-253.

Ward, S. N., 1985. Small scale mantle flow and induced lithospheric stress near island arcs, Geophys. J. Roy. Astron. Soc., 81, 409-428.

Ward, S. N., 1985. Quasi-static propagator matrices: creep on strike slip faults, Tectonophysics, 120, 83-106.

Ward, S. N., and S. E. Barrientos, 1986. An inversion for slip distribution and fault shape from geodetic observations of the 1983, Borah Peak, Idaho Earthquake, J. Geophys. Res., 91, 4909-4919.

Ward, S. N., 1986. A note on the surface volume change of shallow earthquakes, Geophys. J. Roy. Astron. Soc., 85, 461-466.

Barrientos, S. E., R. S. Stein and S. N. Ward, 1987. A comparison of the 1959 Hebgen Lake, Montana and the 1983 Borah Peak, Idaho earthquakes from geodetic data, Bull. Seism. Soc. Am., 77, 784-808.

Ward, S. N., 1988. The North America-Pacific Boundary, An Elastic-Plastic Megashear- Evidence from VLBI, J. Geophys. Res., 93, 7716-7728.

Ward, S. N. and G. Valensise, 1989. Fault Parameters and Slip Distribution of the 1915, Avezzano, Italy Earthquake derived from Geodetic Observations, Bull. Seism. Soc. Am., 79, 690-710.

Ward, S. N., 1989. Tsunamis, in Encyclopedia of Geophysics, ed. D. E. James, Van Nostrand Publishers, Stroudsburg Pennsylvania, 1279-1292.

Ward, S. N., 1990. North America-Pacific Plate Motions: New Results from Very Long Baseline Interferometry, J. Geophys. Res., 95, 21,965-21,981.

Barrientos, S. E. and S. N. Ward, 1990. The 1960 Chile Earthquake: Inversion for Slip Distribution from Surface Deformation, Geophys. J. Int., 103, 589-598.

McNally, K. and S. N. Ward, 1990. The Loma Prieta Earthquake of October 17, 1989: Introduction to the Special Issue, Geophys. Res. Lett., 17, 1177.

Valensise, G. and S. N. Ward, 1991. Long-Term Uplift of the Santa Cruz Coastline in Response to Repeated Earthquakes along the San Andreas Fault, Bull. Seism. Soc. Am., 81, 1694-1704.

Ward, S. N., 1991. Synthetic Seismicity Models for the Middle America Trench, J. Geophys. Res., 96, 19,800-19,810.

Ward. S. N., 1991. Geoculprit, Science, 254, 1822-1823.

Plafker, G. and S. N. Ward, 1992. Thrust Faulting and Tectonic Uplift Along the Caribbean Sea Coast During the April 22, 1991 Costa Rica Earthquake, Tectonics, 11, 709-718.

Ward, S. N., 1992. An Application of Synthetic Seismicity in Earthquake Statistics: The Middle America Trench, J. Geophys. Res., 97, 6675-6682.

Ward, S. N., 1992. Synthetic Quakes Model for Long Term Prediction, Geotimes, 37, 19-20.

Ward, S. N. and S. D. B. Goes, 1993. How Regularly do Earthquakes Recur? A Synthetic Seismicity Model for the San Andreas Fault, Geophysical Research Letters, 20, 2131- 2134.

Ward, S. N. and G. Valensise, 1994. The Palos Verdes Terraces, California: Bathtub Rings from a Buried Reverse Fault J. Geophys. Res., 11, 4485-4494.

Ward, S. N., 1994. Constraints on the seismotectonics of the Central Mediterranean from Very Long Baseline Interferometry, Geophys. Jour. Int., 117, 441-452.

Ward, S. N., 1994. A Multidisciplinary Approach to Seismic Hazard in Southern California, Bull. Seism. Soc. Am., 84, 1293-1309.

Goes, S. D. B. and S. N. Ward, 1994. Synthetic seismicity for the San Andreas Fault, Annali Di Geofisica, 37, 1495-1513.

Jackson, D. D., K. Aki, C. A. Cornell, J. H. Dieterich, T. L. Henyey, M. Mahdyiar, D. Schwartz, and S. N. Ward, 1995. Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024, Bull. Seism. Soc. Am., 85, 379-439.

Ritsema, J., S. N. Ward and F. Gonzalez, 1995. Inversion of Deep-Ocean Tsunami Records for 1987-1988 Gulf of Alaska Earthquake Parameters, Bull. Seism. Soc. Am., 85, 747-754.

Ward, S. N., 1995. Area-based tests of Long-term Seismic Hazard Predictions, Bull. Seism. Soc. Am., 85, 1285-1298.

Ward, S. N. and G. Valensise, 1996. Progressive growth of San Clemente Island, California, by blind thrust faulting: implications for fault slip partitioning in the California Continental Borderland, Geophys. Jour. Int., 126, 712-734.

Ward, S. N., 1996. A synthetic seismicity model for southern California: Cycles, Probabilities, Hazards, J. Geophys. Res., 101, 22,393-22,418.

Ward, S. N., 1997. More on Mmax, Bull. Seism. Soc. Am., 87, 1199-1208.

Ward, S. N., 1997. Dogtails versus Rainbows: Synthetic earthquake rupture models as an aid in interpreting geological data, Bull. Seism. Soc. Am., 87, 1422-1441.

Ward, S. N., 1998. On the consistency of earthquake rates, geological fault data, and space geodetic strain: The United States, Geophys. Jour. Int., 134, 172-186.

Ward, S. N., 1998. On the consistency of earthquake moment release and space geodetic strain rates: Europe, Geophys. Jour. Int., 135, 1011-1018.

Ward, S. N., 1998. A deficit vanished, Nature, 394, 829-830.

Sieh, K., S. N. Ward, D. Natawidjaja and B. W. Suwargadi, 1999. Crustal Deformation at the Sumatran Subduction Zone Revealed by Coral Rings, Geophys. Res. Lett., 26, 3141-3144.

Ward, S. N., 2000. San Francisco Bay Area Earthquake Simulations: A step toward a Standard Physical Earthquake Model, Bull. Seism. Soc. Am., 90, 370-386.

Ward, S. N. and E. Asphaug, 2000. Asteroid Impact Tsunami: A probabilistic hazard assessment, Icarus, 145, 64-78.

Ward, S. N., 2001. Landslide Tsunami, J. Geophys. Res., 106, B6, 11,201-11,216.

Ward, S. N. and S. Day 2001. Cumbre Vieja Volcano -- Potential Collapse and Tsunami at La Palma, Canary Islands, Geophys. Res. Lett., 28, 3397-3400.

Ward, S. N., 2002. "Tsunamis" in The Encyclopedia of Physical Science and Technology, ed. R. A. Meyers, Academic Press, Vol. 17, 175-191.

Ward, S. N. and E. Asphaug, 2002. Impact Tsunami - Eltanin, Deep-Sea Research Part II, Vol. 46, 6, 1073-1079.

Ward, S. N., 2002. Planetary Cratering: A Probabilistic Approach, J. Geophys. Res., 107, E4, 10.1029, p7-1 to 7-11.

Ward, S. N. and S. Day 2002. "Suboceanic Landslides" in 2002 Yearbook of Science and Technology, McGraw-Hill, 349-352.

Ward, S. N., 2002. Slip-Sliding Away, Nature, 415, 973-974.

Schnellmann, M., F. S. Anselmetti, D. Giardini, J. A. McKenzie, and S. N. Ward, 2002. Prehistoric earthquake history revealed by lacustrine slump deposits, Geology, 30, 1131-1134.

Ward, S. N. and E. Asphaug, 2003. Asteroid Impact Tsunami of 16 March, 2880, Geophys. J. Int., 153, F6-F10.

Ward, S. N. and S. Day, 2003. Ritter Island Volcano- Lateral collapse and tsunami of 1888, Geophys. J. Int., 154, 891-902.

Schnellmann, M., F. S. Anselmetti, and S. N. Ward, 2003. Sturm trotz Flaute: Tsunamis auf dem Vierwaldstrattersee, GAIA, 12(4), 13-18.

Chesley, S. R. and S. N. Ward, 2004. Impact-generated tsunami: A quantitative assessment of human and economic hazard, Environmental Hazards, accepted.

Schnellmann, M., F. S. Anselmetti, D. Giardini, J. A. McKenzie, and S. N. Ward, 2004. Ancient Earthquakes at Lake Lucern, American Scientist, 92, 38-45.

Natawidjaja, D. H., K. Sieh, S. N. Ward, H. Cheng, R. L. Edwards, J Galetzka, and B. W. Suwargadi, 2004. Paleogeodetic records of seismic and aseismic subduction from central Sumatran microatolls, Indonesia, J. Geophs. Res., Accepted and in Press.

Ward, S. N., 2004. Earthquake Simulation by Restricted Random Walks, Bull. Seism. Soc. Am., Accepted and in Press.

Ward, S. N. and S. Day, 2004. A particulate kinematic model for large debris avalanches: Interpretation of debris avalanche deposits and landslide seismic signals of Mount St. Helens, May 18th 1980. In Preparation

 

 

 

 

RECENT PUBLICATIONS with THUMBNAIL DESCRIPTION

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Jackson, D. D., K. Aki, C. A. Cornell, J. H. Dieterich, T. L. Henyey, M. Mahdyiar, D. Schwartz, and S. N. Ward, 1995. Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024., Bull. Seism. Soc. Am., 85, 379-439.

A hallmark product of the Southern California Earthquake Center, this work largely builds on Ward (1994, A Multidisciplinary Approach to Seismic Hazard in Southern California, Bull. Seism. Soc. Am., 84, 1293-1309) to develop a multidisciplinary seismic hazard assessment of southern California

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Ritsema, J., S. N. Ward and F. Gonzalez, 1995. Inversion of Deep-Ocean Tsunami Records for 1987-1988 Gulf of Alaska Earthquake Parameters, Bull. Seism. Soc. Am., 85, 747-754.

Written with graduate student J. Ritsema, this paper is one of the first quantitative examinations of a tsunami waveform observed in the deep ocean.

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Ward, S. N., 1995. Area-based tests of Long-term Seismic Hazard Predictions, Bull. Seism. Soc. Am., 85, 1285-1298.

Making earthquake hazard estimates is one thing, devising objective means to test them is another. This paper constructs such tests and applies them to the hazard maps of Ward (1994).

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Ward, S. N. and G. Valensise, 1996. Progressive growth of San Clemente Island, California, by blind thrust faulting: implications for fault slip partitioning in the California Continental Borderland, Geophys. Jour. Int., 126, 712-734.

Repetitive slip on blind faults parent many of California’s landforms, including the Santa Cruz Mountains. This paper quantifies the style and slip rate of the San Clemente blind thrust which is responsible for the creation of one of California’s Channel Islands.

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Ward, S. N., 1996. A synthetic seismicity model for southern California: Cycles, Probabilities, Hazards, J. Geophys. Res., 101, 22,393-22,418.

Physically based models of earthquake recurrence represent the future of hazard estimation. This paper simulates some 5000 years of earthquake history on the southern California fault system using computer models of stress build up and release.

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Ward, S. N., 1997. Dogtails versus Rainbows: Synthetic earthquake rupture models as an aid in interpreting geological data, Bull. Seism. Soc. Am., 87, 1422-1441.

Geological observations of large earthquakes are rare. This paper aims to extract the most information possible from these limited observations by means of carefully tailored computer models of dynamic rupture. Dogtails and Rainbows by the way, are two types of earthquake rupture terminations that can be observed in the field.

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Ward, S. N., 1997. More on Mmax, Bull. Seism. Soc. Am., 87, 1199-1208.

Mmax is the largest earthquake that a fault or set of faults could suffer. Whether Mmax should be based on fault length, or set automatically equal to 8 is controversial. The impact of the choice on hazard estimates is great, but historical data are insufficient favor either. To help, this paper develops computer models of Mmax earthquakes on a range of realistic fault geometries. I find that the Mmax equal to 8 assumption is unlikely.

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Ward, S. N., 1998. On the consistency of earthquake rates, geological fault data, and space geodetic strain: The United States, Geophys. Jour. Int., 134, 172-186.

There are three ways to estimate future earthquake rates: 1) Suppose that the rate of earthquakes in the past will continue; 2) Use geological information and add up the potential earthquake rate from all known faults; 3) Translate the geodetically-observed rate of crustal deformation into an equivalent earthquake rate. The three techniques should give equal values over 1000’s of years, however over shorter durations they do not. This paper first quantifies these rates for several regions of the United States, and then proposes a strategy to best incorporate their diverse opinions into hazard estimates.

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Ward, S. N., 1998. On the consistency of earthquake moment rates and space geodetic strain: Europe, Geophys. Jour. Int., 135, 1011-1018.

Carrying on the approach of paper #8, this article uses space geodesy to map strain rates for all of continental Europe. European strain rates vary from less than 0.09x10-8/y in the British Isles to >7.0x10-8/y in Turkey. In mediterranean Europe, observed seismic moment rates extracted from a 100-year historical catalog account for 56% to 68% of the moment rate predicted from geodesy. In Turkey, the proportion falls to 18%. Although aseismic deformation may contribute to this deficit, the magnitudes of the shortfall coincide with the variations expected in 100-year catalogs.

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Ward, S. N., 1998. A deficit vanished, Nature, 394, 829-830.

In this "News and Views" piece solicited by Nature, I comment on the southern California earthquake rate deficit implied in the Working Group’95 Report (see paper #1). New research suggests that the deficit was an artifact of the incomplete historical earthquake catalog used in the ’95 Report, coupled with several intertwined, and possibly unjustified, assumptions.

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Ward, S. N., 2000. San Francisco Bay Area Earthquake Simulations: A step toward a Standard Physical Earthquake Model, Bull. Seism. Soc. Am., 90, 370-386.

Earthquakes in California’s San Francisco Bay Area are likely to be more strongly affected by stress interaction than earthquakes in any other place in the world because of the region’s closely spaced, sub-parallel distribution of faults. I believe that meaningful quantification of earthquake probability and hazard in the Bay Area can be made only with the guidance provided by physically-based and region-wide earthquake models that account for this interaction. This paper represents a first step in developing a Standard Physical Earthquake Model for the San Francisco Bay Area through realistic, 3000-year computer simulations of earthquakes on all of the area’s major faults.

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Ward, S. N. and E. Asphaug, 2000. Asteroid Impact Tsunami: A probabilistic hazard assessment, Icarus, 145, 64-78..

Tectonics ORU researcher Erik Asphaug and I investigate the generation, propagation, and probabilistic hazard of tsunami spawned by oceanic asteroid impacts. The process first links the depth and diameter of parabolic impact craters to asteroid density, radius, and impact velocity by means of elementary energy arguments and crater scaling rules. Then, linear tsunami theory illustrates how these transient craters evolve into vertical sea surface waveforms at distant positions and times. In the final step, linear shoaling theory applied at the frequency associated with peak tsunami amplitude corrects for amplifications as the waves near land. By coupling this tsunami amplitude/distance information with the statistics of asteroid falls, the probabilistic hazard of impact tsunami is assessed in much the same way as probabilistic seismic hazard, by integrating contributions over all admissible impactor sizes and impact locations.

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Sieh, K., S. N. Ward, D. Natawidjaja and B. W. Suwargadi, 1999. Crustal deformation at the Sumatran Subduction Zone revealed by coral rings, Geophys. Res. Lett., 26, 3141-3144.

Along some tropical coastlines, one tool that is proving useful in illuminating interseismic deformations is coral microatolls. These coral forms fill the role of "tectonic tape recorders" by monitoring variations in relative sea level over decades with an accuracy of about one cm. This paper, co-authored with Kerry Sieh of Caltech, employs 25-year average rates of uplift extracted from coral microatolls to examine previously invisible interseismic deformations along a transect perpendicular to the Sumatran subduction zone.

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Ward, S. N., 2000. Landslide Tsunami, J. Geophys. Res., 106, B6, 11,201-11,216..

In the creation of "surprise tsunami", submarine landslides head the suspect list. Moreover, improving technologies for seafloor mapping continue to sway perceptions on the number and size of surprises that may lay in wait offshore. At best, an entirely new distribution and magnitude of tsunami hazards has yet to be fully appreciated. At worst, landslides may pose serious tsunami hazard to coastlines worldwide, including those regarded as immune. To raise the proper degree of awareness, without needless alarm, the potential and frequency of landslide tsunami have to be assessed quantitatively. This assessment requires gaining a solid understanding of tsunami generation by landslides, and undertaking a census of the locations and extent of historical and potential submarine slides. This paper begins the process by offering models of landslide tsunami production, propagation and shoaling; and by exercising the theory on several real and hypothetical landslides offshore Hawaii, Norway and the United States eastern seaboard. I finish by broaching a line of attack for the hazard assessment by building on previous work that computed probabilistic tsunami hazard from asteroid impacts.

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Ward, S. N. and S. Day 2001. Cumbre Vieja Volcano -- Potential Collapse and Tsunami at La Palma, Canary Islands, Geophys. Res. Lett., 28, 3397-3400.

Geologist Simon Day (University College, London) and I discuss the ramifications of a sudden failure of the western flank of Cumbre Veija volcano on La Palma Island. Simon has mapped a nearly continuous system of headwall cracks from sea level to over 1500 meters elevation. He interprets these cracks as evidence of an incipient landslide that could carry up to 500 km3 of material down the steep margin of the Island at speeds approaching 100 m/s. Support for such a scenario comes from sonar images of adjacent seafloor. These images reveal debris fields of 19 landslides of comparable volume that date from the Pleistocene. My calculations show that tsunami waves generated from a 500 km3 La Palma landslide would reach several hundred meters up the shores of the Canary Islands and would later span the entire North Atlantic basin with palpable amplitude. Because of the westerly direction of the potential landslide, North America is targeted especially. I predict that the East coast of Florida would experience a dozen or more waves of 25 meters height.

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Ward, S. N., 2002. "Tsunamis" in The Encyclopedia of Physical Science and Technology, ed. R. A. Meyers, Academic Press, Vol. 17, 175-191.

Academic Press asked me to write an article about tsunamis to be incorporated in the Natural Hazards section of a new edition of their Encyclopedia of Physical Science and Technology. It was challenging to develop a broad-based article touching upon tsunami generation (earthquake, sea floor landslide, and impact), propagation (geometrical spreading and frequency dispersion), and disposition (shoaling) within the spatial (8,000 words) and technical (Scientific American level) confines of a popular encyclopedia.

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Ward, S. N. and E. Asphaug, 2002. Impact Tsunami - Eltanin, Deep-Sea Research Part II, Vol. 46, 6, 1073-1079.

Employing classical tsunami theory and elementary assumptions about the initial shape of impact cavities, Erik Asphaug and I compute tsunami from the Eltanin asteroid collision at 2.15 Ma. We predict that an Eltanin impactor 4 km in diameter would have blown an initial cavity as deep as the ocean and 60 km wide into the South Pacific and delivered 200-300 m high tsunami to the Antarctic Peninsula and the southern tip of South America 1200-1500 km away. New Zealand, 6000 km distant, would have met 60 m waves. An asteroid the size of Chicxulub (10 km diameter), had it fallen into water deeper than 1000 m, would have sent a 100 m tsunami out to 4000 km distance, even if shoaling amplifications are neglected.

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Ward, S. N., 2002. Planetary Cratering: A Probabilistic Approach, J. Geophys. Res., 107, E4, 10.1029, p7-1 to 7-11.

I develop several statistical formulas governing indices of asteroid cratering. Specific indices include: the fraction of a planet surface expected to be cratered N occasions over a given time interval, the depth of regolith development and the variabilities there of. Naturally, these indices depend upon asteroid flux and the minimum asteroid size threshold imposed by the atmosphere. By feeding estimates of the history of these quantities spanning current conditions to those present on the early Earth, I explore ramifications such as the survivability of crustal fragments and early life forms.

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Ward, S. N. and S. Day 2002. "Suboceanic Landslides" in 2002 Yearbook of Science and Technology, McGraw-Hill, 349-352.

McGraw-Hill asked Simon Day and I to write an entry about underwater landslides for their 2002 edition of Yearbook of Science and Technology. In this 2000 word piece, we talked about the variety of scales of underwater landslides, a bit about their physics, and how they produce tsunami waves. We even managed to mention to wreck of the Titanic in connection with the 1929 Grand Banks Canada landslide.

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Ward, S. N., 2002. Slip-Sliding Away, Nature, 415, 973-974.

Nature asked me to write a "News and Views" piece on a recent GPS finding that a large hunk (2000 km3) of the flank of Kilauea Volcano had moved seaward 10 cm overnight. Knowing that huge volcanic landslides have happened many occasions over geologic time, I discussed the tsunami implications that this huge block might have if it someday slipped into the sea all at once. Tsunami waves would be generated that would span the entire pacific basin. About 20 m high waves would strike here in Santa Cruz. It's a good idea to keep an eye on oceanic volcanoes.

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Schnellmann, M., F. S. Anselmetti, D. Giardini, J. A. McKenzie, and S. N. Ward, 2002. Prehistoric earthquake history revealed by lacustrine slump deposits, Geology, 30, 1131-1134.

During a visit to Zurich, I became interested in an ongoing project by several researchers there at ETH. Using sonar, this group discovered a half-dozen large disturbed layers in the otherwise smoothly stratified bed of Lake Lucerne. From their characteristics, these layers were identified as landslide debris fields triggered by 4 different historical and pre-historical earthquakes. My role in this project was to compute the "tsunami" waves that would be generated in the Lake by these slides. I predict that waves about 4-m height would have been produced by the last quake there in 1601. Four meters is close to the wave size chronicled for the event by eyewitnesses.

The journal Science named this paper as "Editor's Choice".

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Ward, S. N. and E. Asphaug, 2003. Asteroid Impact Tsunami of 16 March, 2880, Geophys. J. Int., 153, F6-F10.

In 2002, several JPL scientists predicted that a 1-km diameter asteroid named 1950-DA had as much as a 0.3% likelihood of striking the Earth on March 16, 2880. Erik Asphaug and I had constructed several simulations of tsunami from asteroid impacts previously, so running a simulation of the waves gerated by 1950-DA seemed be a interesting means to present recent improvements in our techniques. From a supposed deep water impact about 600 km east of the North Carolina Coast, we predicted that most of the U.S. East Coast would suffer waves as high as 100 m. 20 m waves would make it all the way to Europe. Please view our movies of the events at

http://es.ucsc.edu/~ward/1950-DA(5).mov http://es.ucsc.edu/~ward/1950-DA(5_big).mov

The journal Science named this paper as "Editor's Choice" .

9 ______________________________________________________

Ward, S. N. and S. Day, 2003. Ritter Island Volcano- Lateral collapse and tsunami of 1888, Geophys. J. Int., 154, 891-902.

Back in 2001, Simon Day and I wrote a paper on the tsunami expected from a hypothetical flank collapse of a volcano in the Canary Islands. To reinforce the claims in that work, we felt it was useful to model a much smaller, but real, volcanic collapse that happened off New Guinea in 1888. Several eyewitness accounts of events and other nearly contemporaneous observations of the tsunami damage formed a small data set to "ground truth" our calculations. While there remained quite a bit of uncertainty on landslide kinematics, we felt that our approach successfully reproduced the 1888 data and that by extension, our predictions of a mega-tsunami from a much larger Canary Island landslide were defensible.

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Schnellmann, M., F. S. Anselmetti, and S. N. Ward, 2003. Sturm trotz Flaute: Tsunamis auf dem Vierwaldstrattersee (Storms in the Face of Calm: Tsunamis on Lake Lucerne), GAIA, 12(4), 13-18.

This piece was a German language take on our Lake Lucerne work written for the journal GAIA in a special issue dealing with Storms in Nature. This popular article emphasizes the landslide and tsunami modeling aspects of the work. We computed tsunami waves from one of the larger landslides triggered by the 1601 central Switzerland earthquake, placed the results in context with historical information, and discussed implications of the several paleo-landslides that had struck previously.

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Chesley, S. R. and S. N. Ward, 2003. Impact-generated tsunami: A quantitative assessment of human and economic hazard, Environmental Hazards, submitted.

About two years ago, NASA chartered a Science Definition Team to study the need for, and feasibility of, extending the astronomical search to detect and catalog potentially hazardous asteroids and comets (NEOs) whose orbits cross that of the Earth. Currently all NEO's greater than one km diameter are tracked. The extended search would include perhaps hundreds of thousands of NEOs whose diameters are less than one kilometer. Partly as a cost/benefit analysis, Steve Chesley (JPL) and I went through a formal assessment of human and economic hazards associated with tsunami waves generated by impacts. The process is similar to seismic hazard assessments that I have done in the past. Impactor size/frequency, tsunami generation efficiently, tsunami wave spreading, onshore run up and run in, population density and its elevation and distance from the coast all get stirred into the formulation.

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Asphaug E. , D. Korycansky and S. N. Ward, 2003. Exploring Ocean Waves from Asteroid Impacts, EOS, 84, 339.

In 2003, IGPP provided funds for E. Asphaug, D. Korycansky and I to host a conference here at UCSC on potential tsunami waves from asteroid impacts. This piece, published in EOS, summarizes the meeting in a form readable by the full audience of the American Geophysical Union. Safe to say, we don't have all the answers yet.

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Schnellmann, M., F. S. Anselmetti, D. Giardini, J. A. McKenzie, and S. N. Ward, 2004. Ancient Earthquakes at Lake Lucern, American Scientist, 92, 38-45.

This work by the same authors as the 2002 Geology paper (#7 above) gives a popular account of the Paleoseismic research being extracted from the sedimentary history of Lake Lucerne, Switzerland. This paper presents a time line account of how the entire research program unfolded from first recognition of quake-induced landslides to the final conclusions about seismic and tsunami hazard. The casual style of American Scientist and the availability of professional artists to "punch up" the graphics makes it a fun piece to read. As before, my role in the work was the modeling of tsunami waves from paleo-landslides.

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Natawidjaja, D. H., K. Sieh, S. N. Ward, H. Cheng, R. L. Edwards, J Galetzka, and B. W. Suwargadi, 2004. Paleogeodetic records of seismic and aseismic subduction from central Sumatra microatolls, Indonesia, J. Geophs. Res., Accepted and in Press.

For several years now, I have been involved in a project with Kerry Sieh (Caltech) that employs coral microatolls as "tape recorders" of changes in sea level on the west coast of Sumatra. Our interest is to use these corals to map out tectonically induced elevation changes associated with the whole earthquake cycle (both co-seismic and interseimsic). This (large!) paper, mostly the thesis work of Danny Natawidjaja, provides a nearly complete discussion of the coral data set that goes back some 200 years together with our initial interpretations of uplift signals due to historical quakes and subduction zone creep events.

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Ward, S. N., 2004. Earthquake Simulation by Restricted Random Walks, Bull. Seism. Soc. Am., submitted

This paper, explores the use of a certain class of random walks as an earthquake simulator. Surprisingly, humble random walks supply many unifying insights into earthquake behaviors. Random walk theory tells us that not only does b-value control the numerical ratio of small to large earthquakes produced, but b-value also fixes the form of many earthquake scaling laws (mean slip versus fault length, etc.) and the actual shape of earthquake ruptures. I believe that random walk earthquake simulators, in conjunction with physically based simulators, will provide an improved basis for statistical inference of earthquake behavior and hazard.

 

Pen Portrait, Steven Ward

Steven Ward is a solid earth geophysicist who, since 1984, has worked at the Santa Cruz branch of the Institute of Geophysics and Planetary Physics (IGPP), a multi-campus research unit of the University of California. Steve is a theoretical seismologist by training, but he has migrated into the areas of active tectonics and geological hazards. Lately he has contributed to fault-based interpretations of uplifted marine terraces, computer simulations of seismicity and fault interaction, and multidisciplinary assessments of probabilistic seismic and tsunami hazard. Steve is quick to grasp the importance of new technologies in Earth science and is particularly integrative in research. Recent examples of this research style include: the melding of surface slip data from field geology with dynamic rupture models of earthquakes; the use of space geodesy to infer heretofore unquantifiable aspects of earthquake recurrence; the introduction of rigorous probability theory into the hazards of asteroid impact tsunami; and the extraction of long term patterns of subduction zone deformation from the growth rings of shallow marine corals. Steve is proud to be path breaker in multidisciplinary science and he believes that new developments in Earth sensing will ensure that geodynamics will be an increasingly exciting field for years to come.

 

Geophysical Journal International Editor:

For eleven full years ending July 2003, I served as one of the four North American editors of Geophysical Journal International. GJI is the premier Geophysical Journal in Europe. GJI editors are solely responsible to administer all aspects of the evaluation process from manuscript submission, through review and revision, to final acceptance or rejection. I handled about 20 papers per year for the Journal. This editor position provided UCSC and IGPP wonderful international exposure (see Frontpiece Attachment A1).

 

Vision Statement: "Tectonics in the Next Decade" (written Spring 2002)

Of all of the University of California campuses, I should think that Santa Cruz should be keenly aware of tectonics. UCSC’s buildings shake violently from periodic ruptures of one of world’s most active faults, the San Andreas, just a stone-throw away. The beaches surrounding UCSC drown now and again from tsunami waves parented from undersea earthquakes, both distant ones and those that happen right offshore. The very ground on which UCSC perches has been shoved up from the sea in a geological eye blink. The hand of tectonics on the Santa Cruz landscape is seen everywhere.

At UCSC especially, I believe that tectonic studies remain as exciting and rewarding today, as they were 15 years ago when the Institute of Tectonics was christened. I view the next decade as presenting even more wondrous opportunities to see the Earth operate and to understand the physical processes behind the operations. The opportunities ‘to see’ lie in new technologies that precisely monitor the fingerprints of tectonics. Deformations of the Earth can now be tracked over most any time or space scale that you can imagine. Networks of digital seismometers image earthquake ruptures expanding at 6,000 miles per hour. Space geodetic instruments perceive Chicago drifting from Boston at a rate 1000 times slower than your fingernails grow. Quizzically, deformation is both the cause, and the effect of tectonics. The opportunities ‘to understand’ lie in evermore complex computer simulations of what we see. Computer models, like nothing else, have the abilities to tie together theory, experiment, and observation into a single package and to allow the operator to "turn the knobs" to grasp the importance of this or that piece of the puzzle. Computer modeling of tectonics however, is not all a game. It is fully reasonable and desirable, even at this early stage, to employ numerical simulations of earthquake recurrence on all of the faults of the San Francisco Bay Area to help estimate their hazard. So far, we have only had a taste of computer models in tectonics. In the next decade, I picture people "calling up" earthquake forecasts on their PC, much like we summon weather forecasts today. With exploding opportunities to see and to understand Earth movements, the next decade should be a golden era for tectonics, especially here in Santa Cruz where its touch is so strongly felt.