Research Field - Geophysics & Geology
Geophysics and Geology deal with the composition and structure of the Earth by studying and observing the physical characteristics of processes that occur on or below the surface. The research includes many fields such as seismology (earth quakes), oil and water exploration, environmental quality (pollution of underground water and the coastal waters), remote sensing of the surface (image processing) and oceanography (marine sciences). The researchers in these areas are developing methods to study the inner Earth using seismic waves, magnetic fields, gravity, and mathematical and physical models to understand the processes and forces behind phenomenon like plate tectonics, ocean formation, mountain building, volcanoes and earthquakes. These research tools are also applied to solving problems related to strengthening buildings, and finding natural resources.
Seismic methods – based on the theory of acoustic waves. In this method we measure the propagation speed of sound waves in the internal layers of the Earth. The sound velocity of waves depends on the physical characteristics of the rock. The seismic waves are entered into the Earth by explosions or hitting the surface with a hammer or weight. Seismic methods are the most important methods in oil exploration in Israel and the world. The data is then inserted into models for analysis and interpretation. In this way we can obtain a picture of the sub-surface below the continents and oceans, including the thickness of the layers, their geometric slope below the surface, location of faults, anticlines, synclines, and salt bodies.
Magnetic methods – These methods measure the Earth's magnetic field. Since the source of the Earth's magnetic field is within the core of the Earth, monitoring the changes in intensity and direction of the field tells us about processes occurring within the core. This method, based on the difference in magnetic properties of rock is useful in locating core deposits, buried archeological sites, and rock types underground.
Gravity methods – These methods measure the different mass and location of rocks below the surface, as a tool to interpret the inner structure of the Earth. This method allows us to detect geological structures and different rock types.
Remote Sensing – Using satellites and planes is an important and efficient way of studying the Earth by frequently observing areas that may be difficult to access. Images from aircraft or satellite, together with measurements on the surface can provide information that is hidden to the eye. The applications of these methods are found in: environmental quality, geology, hydrology, agriculture, forestry and climate phenomenon.
The use of new space technologies allows us to measure the motion of the tectonic plates and the stress created in the crust between earthquakes.
Earthquakes are one of the most damaging natural hazards on Earth. They normally occur along the boundaries of the tectonic plates. Using GPS measurements together with seismic measurements at the surface allow us to perform innovative research describing the nature of earthquakes and better understand their formation.
Work of a Geophysicst
Planning and performing research using different physical methods and tools, and the appropriate analysis and interpretation of the observations to get information on the composition and structure of the geological strata below the surface, information that cannot be obtained on the surface. In most regions where exploration for natural resources takes place, it is difficult to know what lies underground due to the surface being covered by vegetation, water, lakes, or the layers are buried deep below the surface. Hence the information about the sub-surface can only be obtained using geophysical methods. Geophysicist are often part of teams on land and on ocean ships that carry geophysical equipment to study the deep oceans, and the structure of the crust below our feet and under the oceans.
Earthquake source seismology
Imaging of fault slip and finite fault inversions
Usage of non-traditional seismic networks for monitoring active faulting
Prof. Evgeny Landa (Emeriti)
- Seismic Inversion: pitfalls and challenges Full waveform inversion (FWI) attempts to estimate a velocity model that minimizes the difference between measured and simulated data.
Unfortunately, these inversion schemes have little success except on some synthetic data experiments. Fundamental problem with this approach is that do not know how well any of our forward modeling approximates natural processes. Seismic waves that propagate in the earth hardly satisfy any wave equation. Our inversion algorithms can therefore not be expected to fully reverse the natural physical processes that have produced our data, and errors are bound to arise.
- Seismic Diffraction Imaging
Diffraction imaging is at the core of the seismic diffraction method.
The diffraction image represents the subsurface location of geological features such as faults, pinchouts, karsts, fracture zones etc. which produce diffraction. Successful diffraction imaging essentially involves separation between reflective and diffractive components of the total wavefield, attenuation of the reflection energy and imaging the residual diffractive component
Seismic sensing with optical fibers (Distributed Acoustic Sensing), Microseismic and induced seismicity monitoring, Near-surface geophysics
Active tectonics, earthquakes, Paleoseismology and earthquakes in the Middle East, Seismites and soft sediment deformation, Paleo- and archaeo-seismology, Paleomagnetism, secular variations of the Earth magnetic field, Anisotropy of Magnetic Susceptibility, archaeomagnetism
Seismic data analysis and imaging, Algorithm development for seismic exploration, Geological model-building and prospect generation for subsurface drillingת Design of seismic surveys, Global earth crustal studies.
My study aims to improve the understanding of earthquake mechanics. I combine data analysis and modeling in my studies, and related work that I have performed includes time-space analyzes of earthquake catalogs, numerical modeling of seismic faults, comparison between simulated and natural earthquake catalogs, co-seismic slip inversions and design of earthquake early warning algorithms.
Dr. Lev Eppelbaum (Principal Research Assoc.)
Processing, interpretation and modeling of potential geophysical fields (gravity, magnetic, thermal and self-potential), VLF data and induced polarization. Environmental geophysics, Application of statistic-probabilistic methods and information theory in geophysics, Archaeological geophysics, Analysis of different earthquake's precursors, Tectonics, geodynamics and paleomagnetic reconstructions.