2006 PNACP Conference

Abstracts

Stacking your Physics Courses: A Good Idea or a Tragedy Waiting to Happen?
Grant C. Eastland, Blue Mountain Community College

When low enrollment is a problem, offering both the trig-based and calculus-based general physics sequence is challenging. When you are informed that you can only offer one sequence but have nearly enough to offer both what does one do? The answer is to stack the courses. Administratively, the instructor is just teaching one course, but realistically they are teaching two. In the beginning, this venture of teaching the trig-based course simultaneously with the calculus-based course seems rather outlandish. However, the task can be done successfully if one employs the correct approach. A traditional lecture-textbook approach can work, but is probably not the best way to do things because certain topics in the calculus-based course may have to be skipped due to their mathematical difficulty. The ideal way to stack your physics sequence is to teach them utilizing a workshop physics approach, where students “discover” the laws and principles of physics by doing daily hands on activities and experiments. This approach allows your students to become more involved in their own learning of the subject matter and they will find it more enjoyable.

A Short Primer in Geophysics
Steven Hoffmaster, Gonzaga University

A short presentation of some of the basic physical principles applicable to Geology. This includes magnetism, seismic wave speed, and pressure and density variations. Geological exploration techniques will also be discussed.

Using Isotopic Models to tell Geologic Time
Jose Miguel Hurtado, Jr., University of Texas at El Paso

The past two decades have seen the exciting growth of a variety of ingenious and powerful uses of isotopic chemistry and physics to mark the passage of geologic time. These analytical methods are varied in their fundamental systematics and applicability and give geoscientists access to a wealth of information about Earth processes and history. Among these are ⁴⁰Ar/³⁹Ar and (U-Th)/He thermochronology, and cosmogenic nuclide geochronology. The former are important methods for constraining the thermal evolution of the crust as well as for reconstructing exhumational and uplift histories, such as the tectonic evolution of the central Nepal Himalaya. The later is a novel and increasingly sophisticated approach to the previously intractable problem of determining the ages of geomorphic surfaces. Such knowledge is critical for determining, for example, rates of climate change and very recent, potentially hazardous, tectonic activity related to earthquakes.

Rocks, Fossils, and Meteorites from the Inside Out: Geological Applications of High Resolution X-ray Computed Tomography
Bill Carlson, University of Texas

High-resolution and ultra-high-resolution X-ray computed tomography are rapid, non-destructive, and extremely powerful techniques for 3-D examination and measurement of diverse geological materials and specimens with sizes from several millimeters to several decimeters. Sequential contiguous images are compiled to create 3-D representations that can be manipulated digitally to perform efficiently a large array of visualization and measurement tasks. Geological applications include interior examination of one-of-a-kind fossils or meteorites; quantitative textural analysis of igneous and metamorphic rocks; geometric description and quantification of porosity and permeability in rocks and soils; and any other investigation demanding 3-D data that formerly required physical serial sectioning.

Visceral Physics -- Using Motorcycles to Teach Mechanics, Thermodynamics and Acoustics
Martin Hackworth, Idaho State University

Introductory Physics courses provide a rich palette of opportunity to approach difficult concepts in a novel manner that both informs and piques interest. Martin Hackworth uses two-wheeled inline vehicles to illustrate many of the topics commonly encountered in first semester introductory courses. This talk will provide a brief review of motorcycle dynamics appropriate for introductory courses and examples of applications.

Exploring time and velocity dependent forces on rockets in the upper division lab
John Larkin, Whitworth College

We fly medium-powered rockets (4' to 6' tall) carrying altitude-recording electronics. The students then model the motion due to the time-dependent (rocket motor) and velocity-dependent (air resistance) forces and fit it to the data.

Earthquakes, Volcanoes & Tsunami -- The case for Prediction, Early Warning & Rapid Notification
Steve Malone, University of Washington

Earthquakes are critical to the prediction of volcanic eruptions and tsunami, yet currently there are no accepted ways to predict earthquakes. However, prediction attempts are being made and there are now ways to predict strong ground motion once an earthquake has started. Over different time periods, and using different techniques, science and technology can contribute to the mitigation of hazards from these rare but potentially devastating geophysical events.

Viscous Drag of Upper Mantle on the Lithosphere
David Terrell, Warner Pacific College

Physical conditions in the Upper Mantle such as convection can be used to infer a viscous drag on the lithosphere by using fluid dynamics and the rheological properties of the system. When an asymmetrical convection and other values such as average density (say 3.4 g/cc) are assumed, one can calculate a drag of about 3400 bar. This shear stress is enough to break material such as those in the crust, implying that a young earth with a crust of less than 10 km thick will break, initiating continental drift.

Hubbert's Peak in a Toy Model of Oil Extraction
Richard Wiener, Pacific University

Intraslab earthquakes in the Cascadia Subduction Zone
Ken Creager, University of Washington

This talk will review our current understanding of the earthquakes that occur within subducting oceanic plates, with a focus on the intraslab earthquakes of the Cascadia subduction zone. The three largest earthquakes in Washington during the past 100 years have all been intraslab quakes. We have analyzed travel time data from local earthquakes and from several active-source experiments to determine accurate earthquake locations and 3-D seismic wave speeds. At the same time, we analyze times of seismic phases that reflect off the crust-mantle boundary (Moho) of the subducting plate to determine its
location relative to the earthquakes. The reflector separates intraslab earthquakes into two groups, permitting a new understanding of the origins of intraslab earthquakes in Cascadia. Earthquakes up-dip of the Moho's 45 km depth contour occur below the reflector, in the subducted oceanic mantle, consistent with serpentinite dehydration, while earthquakes located down-dip occur primarily within the subducted crust, consistent with the basalt to eclogite transformation. To compliment this analysis of structure, we examine the detailed rupture history of the 2001, Mw 6.8, Nisqually intraslab
earthquake using seismograms recorded on the recently installed strong-motion network. This earthquake initiated at 52 km depth, south of the region where reflected waves constrain Moho depth, but at the extrapolated location of the subducted Moho. Rupture propagated primarily to the north along the strike of the slab, with a slip of about 1 meter on a 20-km long fault. Being elongated along strike, and apparently on a fault that is sub-parallel to the slab, this earthquake could just fit within a 7-km thick subducting oceanic crust. Whether intraslab earthquakes are constrained to occur within the subducted crust is important because the largest earthquake that can geometrically fit within the 7-km thick crust is about Mw 7, while an earthquake that ruptures the entire 20-km thick subducting lithosphere could be 30 times larger, Mw 8. This region, about 100 km south of Seattle, has experienced 3 magnitude 6.5 to 7.1 earthquakes during the past 100 years. I will also briefly review the exciting new results on episodic tremor and slip. Very slow earthquakes, of moment magnitude 6 to 7 occur every 14 months under the Olympic Peninsula and Vancouver Island. The duration of slip is a 2-3 weeks and these events are detected geodetically as well as from tremor recorded on seismograms.

The 2004-06 Eruption of Mt. St. Helens: Style of Eruption, Methods of Monitoring, and Lessons about Cascade Volcano Hazards
Robert Butler, University of Portland

Applications of physics to observations of volcanoes has greatly advanced volcano monitoring since the catastrophic eruption of Mt. St. Helens in 1980. Earthquake observations remain a fundamental component of monitoring programs and recognition of harmonic tremors can sometimes provide warning of an imminent eruption. New methods include high-resolution GPS, light detection and ranging (LIDAR), and forward-looking infrared (FLIR) photography. With all of these methods being applied at Mr. St. Helens, the ongoing eruption is surely the best-documented eruption in history. While these methods are furthering our understanding of volcanoes, it is uncertain whether our ability to monitor and mitigate volcanic hazards is advancing as rapidly as Pacific Northwest populations are encroaching on Cascade volcanoes. Mudflow hazards to the southern Puget Sound region from Mt. Ranier provide an interesting example.

The Night Sky: How Dark, How Clear, How Stable?
Robert Ruotsalainen, Eastern Washington University

The detectability and measurability of astronomical objects depend on at least three local properties of the earth's atmosphere. The quality of astronomical observations is affected by the darkness of the night sky, the transparency of the atmosphere, and the seeing associated with atmospheric turbulence. In this presentation all three factors are reviewed briefly.

Examination of Shallow Subduction Zone Processes in Central Costa Rica Using Large Earthquakes and Microseismicity
Susan Bilek, New Mexico Institute of Mining and Technology

The majority of global seismic moment release occurs in shallow subduction zones, as evidenced during the December 2004 magnitude 9+ earthquake in the Sumatra subduction zone. There are many important questions associated with subduction zones, including what controls limits on earthquake rupture and how heterogeneous fault zone conditions impact both large and small earthquakes occurring along the Costa Rica portion of the Middle American subduction zone.

Geophysics in a Complex World
Stephen Moysey, Clemson University

High-resolution imaging with ground-penetrating radar (GPR) has important applications for understanding geologic processes, ranging from linking sedimentary deposition with global change to predicting the migration of contaminants in groundwater. New data interpretation methods based on pattern recognition are making GPR a more reliable tool for detecting geologically significant regions in complex environments. However, scattering of electromagnetic energy and spatially variable wave velocity are challenges that continue to make accurate imaging of highly heterogeneous media with GPR difficult.

How Green is My Monitor?
David McKinstry, Eastern Washington University

No, not "Is my monitor energy efficient?" Rather, "How pure are the red, green, and blue colors of a monitor?" We all know that supposedly 16 million colors can be produced using 256 levels of intensity for each of the primary colors, and it seems to work quite well. However, out of curiosity, an analysis of the color spectra of three kinds of computer monitors is made. These are the standard CRT, the LCD, and DLP monitors. A report is made on the results of that analysis.

Angels in Images?
Allan Greer, Gonzaga University

A few years ago I received a call from a local Spokanite. He said he wanted to talk about Electromagnetic theory in regard to something he had recently been dealing with. I agreed to meet, and soon he came to my office. What he told me had very little to do with Electromagnetic theory (at least as far as I could tell). Details (sketchy though they may be) to come.