Research Activities
Dr. von Frese's research activities at OSU have focused mostly on investigating the utility of satellite measured magnetic and gravity anomaly fields for obtaining new insight on the properties and processes of the Earth's crust. Such insight is important for improving our knowledge of the evolution in space and time of the outer part of the Earth, including its atmosphere, biosphere, mineral and energy resources, and crustal hazards (e.g., earthquakes, landslides, volcanic activity). He has also conducted research on the application of geophysical methods for the exploration and characterization of archaeological and engineering sites.
Considerable research has been undertaken to identify the regional-scale features and properties of the lithosphere and core-mantle boundary from integrated satellite, airborne and surface geophysical data.
(Magsat and its ground tracks over the Russian Arctic)
His group developed and published procedures that permit the detailed analysis and modeling of crustal components in satellite measured magnetic and gravity anomalies. In particular, his group was able to demonstrate with these capabilities that NASA's satellite magnetic observations provide important constraints on reconstructions of the continents (e.g., Pangea and Gondwana).
His group studied the problem of extracting the crustal components in NASA's satellite (Magsat) magnetometer observations over the Antarctic. This was an especially difficult problem because these data were collected during the Austral Summer when the observations were severely contaminated by signals from highly agitated external (auroral) magnetic fields. As a result of these research efforts, his group discovered and published the theory of spectral correlation. Satellite orbits that are close to each other relative to their altitudes above the Earth's surface contain repeatable or correlative signals related to the static geology of the crust that may be separated by spectral correlation filters from incoherent signals of the highly dynamic external fields.
Using spectral correlation theory, his group produced and published state-of-the-art procedures for reducing satellite magnetic observations for their core field, external field, and lithospheric field components.
These procedures will be used to process the
satellite magnetic observations for crustal features from the pending European Space
Agency (ESA)/NASA Oersted mission. As an Oersted investigator, he is helping NASA to
prepare procedures for servicing the data reduction and analysis requirements of the
mission (1995-1997), process the data during the mission (1997-1999), and conduct
follow-on crustal studies of the mission data (1999-2003). The Oersted mission data will
also be used to support an international effort to produce a magnetic anomaly map for
the Antarctic (Figure: ESA's ERS1 Satellite).
His group adapted its magnetic data reduction and analysis procedures to the problem of extracting marine gravity anomalies from satellite altimetry with remarkable success. Supported by NASA and matching industry funding, these procedures have been applied to the U.S. Navy's Geosat-GM and ESA's ERS « satellite altimetry data to obtain marine gravity anomalies of unprecedented detail and accuracy. His group is currently working to document these procedures for publication. These procedures will be used to investigate the crustal properties of the poorly known continental platform regions of the Arctic and Antarctic.
His group adapted spectral correlation theory to compare geopotential field anomalies observed at common observation coordinates for developing new and enhanced insight on the crust. In particular, improved models of Ohio's crust have been developed and published based on the spectral correlation analysis of the state's magnetic and gravity anomaly fields. His group is also in the process of documenting a new isostatic model for Ohio's crust from the spectral correlation between the state's observed gravity field and the gravity field modeled from its topography.
(Ohio terrain-correlated free-air gravity anomalies and Precambrian crustal thickness model
obtained by spectral correlation)
His group is currently working with colleagues from OSU's Dept. of Materials Science & Engineering to develop procedures for modeling crustal stress from the isostatic data that may help to account for Ohio's earthquake activity. The origin of intraplate earthquakes such as found in Ohio is a frontier area of inquiry in the geosciences. If this interdisciplinary effort is successful, additional studies will be undertaken on the crustal stability of Ohio and other states with major energy producing facilities (e.g., nuclear power plants), as well as how crustal stress fields may influence the intraplate distribution of mineral and energy resources, earthquakes, and other crustal features of great societal and scientific concern.
His group developed the new theory on modeling the isostatic properties of the crust from
anomaly correlations between the observed and topographic gravity fields in a study of the
Moon's crust using DoD/NASA's Clementine satellite gravity and laser altimetry data. This
study, which was funded by an OSU interdisciplinary seed grant and carried out with colleagues
from the Center for Mapping and Dept. of Civil & Environmental Engineering and Geodetic
Science, has resulted in a paper that has been submitted for publication on the crustal
properties of the spectacular Mare Orientale impact basin. His group is working to expand this
study to the entire crust of the Moon in anticipation of the requirements for analyzing the
gravity, magnetic, and topographic data that will be collected by the pending Lunar Prospector
mission. The group also plans to extend these activities to a crustal analysis of Mars where
gravity and topographic data will soon be returned by the Mars Surveyor mission
(Figure: The Earth and the Venus, two sister planets).
In another application, his group studied the spectral correlation between satellite measured
gravity and topographic gravity anomalies of the Antarctic. The results of this study, which
have been submitted for publication, suggest that much less continental crust may exist beneath
the ice sheet of East Antarctica than is commonly assumed. His group is currently developing a
magnetic anomaly model for the isostatically compensated Antarctic crust for comparison against
satellite (Magsat and pending Oersted) magnetic observations. A good comparison between the two
data sets would be the first evidence ever produced for the existence of a crustal
"magnetoisostatic" effect.
This effect may also be the cause of the poor correlation that is commonly observed between satellite measured magnetic anomalies and large-scale compilations of near-surface magnetic anomalies such as have been produced for North and South America, Africa, Australia, India, and the Arctic. The objective for the production of such magnetic anomaly compilations is to obtain enhanced insight on the evolution and features of the crust. However, the reduction of near-surface magnetic observations from airborne, shipborne, and terrestrial surveys for crustal anomalies commonly produces long-wavelength errors (e.g., secular variations of the core field, leveling of adjacent surveys, etc.) that can greatly distort magnetoisostatic anomalies which in satellite surveys may be present with minimal distortion. Hence, demonstrating the existence of magnetoisostatic anomalies will, in addition to providing new scientific insight on the crust, also demonstrate the necessity for using satellite measured magnetic anomalies to augment near-surface magnetic measurements for a more complete picture of the magnetic properties of the crust.
(Conceptual models for Midcontinent hot dry rock geothermal resources)
A significant complication to interpreting crustal correlations in topographic, gravity, and magnetic data is the presence of heat flow anomalies related to variations of geothermal flux beneath the crust and the distribution of radioactive elements and other heat sources within the crust. His group is currently developing spectral correlation and modeling procedures to quantify relationships between heat flow and topographic, gravity, and magnetic anomalies of the crust.
With the increasing availability of regional magnetic, gravity, and topographic data for the Arctic and Antarctic, his group has begun a comparative analysis of the lithospheric features and processes of the north and south polar regions. This investigation also includes efforts to determine the properties of the core-mantle boundary in the two polar regions from combined analyses of the Earth's geoid and main magnetic field.
The research interests and activities of his group also include the development of high resolution geophysical procedures for investigating archaeological and engineering sites.
As part of an NSF funded project to anthropology colleagues at Michigan State University, he conducted a magnetic survey of the Ft. Ouiatenon site in west-central Indiana that revealed the distribution of a number of important 18th century artifacts. Several of the archaeological site investigations that he has performed have been funded by the Army Corps of Engineers in conjunction with major engineering projects such as the Tennessee-Tombigbee Waterway and Clark Maritime projects.
(Ft. Ouiatenon archaemagnetic anomalies and some of their sources)
Research efforts have also focused on seismic, magnetic and electrical methods for high resolution imaging of archaeological features of the Justinian Fortress of Isthmia near Corinth, Greece, which is being excavated by the American School of Archaeology under the management of OSU colleagues in the Dept. of History.
His group is currently working with colleagues from the Center for Mapping and Dept. of Civil & Environmental Engineering and Geodetic Science on integrating inertial navigational systems (INS) with global positioning systems (GPS), to facilitate the implementation of high resolution mobile geophysical surveying for environmental, engineering, and archaeological applications. The objective here is to develop a portable, real-time positioning system that allows the surveying crew to determine its ground position in much the same way that aircraft currently operate. The positioning accuracy required in these applications is on the order of a few centimeters or less. The development of such a piloting system will greatly facilitate ongoing projects and the competitiveness of proposals for field geophysical investigations in engineering and archaeological applications.