AU2001100655A4 - Method of morphometric analysis - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 INNOVATION PATENT SPECIFICATION

(ORIGINAL)

Name of Applicant: Diana Ivanova Polonska of 9/59 Kensington Road, Kensington 2033, New South Wales.

Actual Inventor(s): Diana Ivanova Polonska Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne 3000, Victoria, Australia Innovation Patent specification for the invention entitled: "Method for Morphometric Analysis" The following statement is a full description of this invention, including the best method of performing it known to me: Q:\OPER\SSB\2486714COM.DOC 18/12/01 P:\oper ssb\2486714spec.docI8/12/I -1- METHOD OF MORPHOMETRIC

ANALYSIS

FIELD OF THE INVENTION The present invention relates to a method of morphometric analysis. More particularly, the invention relates to methodologies for determining subsurface inhomogeneous structures in the lithosphere (exhibiting at present or in the past different physical and chemical properties) through delineation and analysis of naturally predetermined elements of the Earth's crust.

BACKGROUND OF THE INVENTION Earth's crust, constituting the outer shell of our planet, is directly linked to the state of the environment and the continued survival of the planet's inhabitants. It is a complex structure which continues to shift and change over time. Detailed knowledge of Earth's crust local manifestations is a key to many problems of scientific and applied disciplines.

A wide array of practical applications ranging from prospecting minerals to infrastructure planning and seismic zonation require detailed description of the subsurface structures.

Obtaining such information for a wide area, however, requires prohibitively costly and labour-intensive techniques. Drilling, tunnelling or mining information and geophysical exploration data are typically either very limited or do not provide sufficient coverage and clarity. In addition to that, direct analysis techniques have depth limitations. Their sequential character leaves a large degree of uncertainty in spatially locating subsurface discrepancies on a few tens of kilometres wide territory or similar scale. Indirect measurements analysis of seismograms) are largely instrumentation-dependent and very often interpretation of such data can vary significantly.

In many applications, insufficient data regarding the extensive areas of interest results in lack of integrity and only coarse spatial resolution, thus giving inherently unreliable estimates. In particular, seismic zonation is one of the applications with such problems.

P:\oper\ssb\2486714spec.doc-18/12/Oi -2- Due to the current limitations in resolving subsurface irregularities, and consequently distribution of the ground motion, there is inadequate understanding about how earthquakes are generated and how their energy is released and distributed throughout affected areas.

To provide application-specific solutions to the abovementioned problems, investigations of a parallel character are needed. In principle, when the only available sources of information include topographic maps (aerial photographs) of sufficiently high resolution, the presently proposed methods can be applicable to the regions with little or no preceding geotechnical field surveying. Additional data and field checks can be very helpful, but they do not govern the main conclusions of the proposed cameral, parallel approach.

Instead of relying primarily on field observation methods to investigate the subsurface structures, the proposed cameral analysis is based on applying the principles of geomorphology for analysing subsurface structures. Geomorphology is the study of landforms and their formation and development as a result of endogenous (internal, tectonic) and exogenous (external) forces acting on the Earth's crust. Its main area of focus is the interaction between the lithosphere and the atmosphere and/or hydrosphere.

Reconstruction of the most likely scheme of local landform development over long periods of time provides an indication of the likely inhomogeneities present in the land area, and thus provides crucial information about local manifestations of events affecting the Earth's crust, for example earthquakes.

Structural geomorphology, also known as tectonic geomorphology, deals with the resistance of earth materials to degradational processes over long period of time. This subdiscipline of geomorphology went through decades of development, with different schools pursuing study of regional tectonics. The methodology described in this patent application uses the terminology, initially evolved from that of morphostructural analysis, introduced in the 1940s and widely accepted in the geoscience schools of the former USSR and Eastern Europe.

P:\oper\ssb\2486714spec.doc-18/12/01 -3- SUMMARY OF THE INVENTION The present invention provides a method of morphometric analysis of lithospheric component structures within a predetermined area of the Earth's crust, including the steps of: delineating blocks within said component structures based on a plurality of different thematic maps of said predetermined area; grouping said blocks into one or more macroblocks according to a plurality of predetermined morphometric values and coefficients associated with each block by comparing respective ones of said morphometric values and coefficients of each block with ones of said morphometric values and coefficients of at least each adjacent block to determine common morphometric properties of the blocks; iteratively redefining the macroblocks according to statistical analysis of each of the morphometric values and coefficients of all of the blocks within the macroblock.

The present invention further provides a system for morphometric analysis of lithospheric component structures within a predetermined area of the Earth's crust, including: means for delineating blocks within said component structures based on a plurality of different thematic maps of said predetermined area; means for grouping said blocks into one or more macroblocks according to a plurality of predetermined morphometric values and coefficients associated with each block by comparing respective ones of said morphometric values and coefficients of each block with ones of said morphometric values and coefficients of at least each adjacent block to determine common morphometric properties of the blocks; and means for iteratively redefining the macroblocks according to statistical analysis of each of the morphometric values and coefficients of all of the blocks within the macroblock.

Preferably, the system and method described above are effected by use of a computer.

P:\oper\ssb\2486714spec.doc.18/12/Ol -4- Embodiments generally relate to a method of modelling a naturally predefined hierarchical structure of the Earth's crust. The elements of the Earth's crust three-dimensional blocks of different hierarchical ranks are relatively loose (tectonically) dynamic units. The smallest blocks and their combinations are generally situated closer to the surface. The bigger blocks of higher rank correspondingly have their foundations at deeper levels, ultimately reaching asthenosphere. Having certain degrees of freedom, the blocks and their combinations may undergo significant movement in all three dimensions over periods of time (on a geological scale). Exogenous forces may drastically change the relief of the Earth's surface (erosion, when traces of landscape evolution are significantly eliminated, is an apparent example), while endogenous forces may lead to mutual uplifting, subsidence, bending over, forming faults and so on. Therefore, different scenarios of acting forces may lead to seemingly similar state of modern landforms. However, taking into consideration the proposed method of modelling, statistically irregular patterns can be revealed through delineation and consequent analysis of the corresponding block structures of the regions.

By adopting this method of modelling, one can assume that the block structures, reflecting inhomogeneous structures of the area under investigation, are naturally predefined. Despite largely eliminated evidences of landscape evolution and smoothing of tectonic relief, footprints of the blocks can still be depicted on various morphometric maps. With different types of morphometric maps pointing to the same possible borders of blocks, the probability of correct reconstruction of the blocks is increased. Correspondingly, statistical analysis of morphometric characteristics for supposedly distinctive blocks will result in more affirmative conclusion of delineated earlier block boundaries. Sister blocks with similar morphometric values and coefficients, formed within a larger parent block, will exhibit similar three-dimensional movements in comparison with sister blocks of another parent block a block of higher rank. Block structures of higher rank, comprising blocks of lower rank (and/or smaller block structures) similarly exhibit distinguishing characteristics among themselves. Any sufficiently big part of the surface can thus be divided (according to the available input data) into blocks.

One preferred embodiment relates to a method of delineating the surface within a given territory into blocks elementary units of the analysis at a predetermined level of P:\oper\ssb\2486714 spccdoc- 18/12/01 magnification, and subsequent statistical verification of the delineation. The abovementioned ranks of blocks correspond to the different levels of magnification for the analysis. The method includes the steps of: Delineation of blocks and outlining the sketch of the block structure, which includes the steps of: i. Creating a hypsometric map of the region for investigation. Such a map represents a range of altitude variations characteristic of a particular area. Such a map for a mountainous area with thousands of meters difference between the lower and the higher average height of local landforms will significantly differ from a map for a plain area, where differences in height are orders of magnitude smaller.

Input maps for the analysis should not be interpreted in a narrow sense, and any suitable technique resulting in creating topographic maps, such as producing aerial photos, satellite images, spatially distributed satellite altimetry digital data, Digital Elevation Model (DEM) data etc. will be considered as obtaining an input map.

This may be regarded, loosely, as raw data initial map; ii. Creating map of lineaments for the territory of investigation. Such a map can be compiled from initial data, such as a topographic map, satellite imagery and so forth; iii. Performing contouring of the recognisable tectonic relief (contrasting combinations such as river beds and valleys; low hypsometric steps and corresponding maximum marks; relief-forming faults, based on various features; chains of lakes, etc.), based on the maps of the previous two steps, and those to follow in consequent steps. This procedure, when used in conjunction with any of the steps below, enables the delineation of possible block borders. Drastic or significant change in map-specific values (such as slope angle for the map of slope angles) provides an indicator for such contouring. The probability of correct delineation of such borders increases, when more additional maps (more steps of the analysis) point to the same spatial location of such borderlines. Steps ii-vi can also be concurrent, depending on the circumstances of a particular area. Upon repeating steps and steps not gaining new information can be skipped; P:\oper\ssb\2486714specdoc.l 8/12A0 -6iv. Creating a drainage network map for the specified area, based on the initial map (usually topographic map). A suitable technique to do that (including the use of modern commercially available software tools such as GIS packages) will be known to a person skilled in the art. An iteration of a block's delineation can be achieved on this step as the blocks of increasing rank can be assumed to be located between the streams of increasing order. Borders defined in such a fashion, along with the borders described in the previous step iii, will constitute surfaced borderlines of particular blocks; v. creating a map of slope angles. Creation of such a map can be done by the procedures of contouring described in step iii; vi. creating a map of tectomorphoisohypses, resulting from hypsometric map.

Creation of such a map can be done by the procedures of contouring described in step iii; vii. creating other thematic maps, relevant to the particular case study, which can be relevant to geomorphic circumstances of the territory under investigation.

Creation of such maps can be done by the procedures of contouring described in step iii; generating corresponding geomorphological hypotheses about the blocks' geometry and positioning, their mutual hierarchy and three-dimensional tectonic movement. Repeating the necessary procedures of the step to narrow the search spaces when certain geomorphological hypothesis does not result in improved spatial resolution; (Geomorphological hypotheses reflect the possible interplay of exogenous and endogenous forces during the development of a landscape. For example, if we have two blocks with drastically different slope angles, it may mean 1) either different rock denudation characteristics of the materials comprising each of the blocks, or 2) significantly different influence of such external factors as weathering under high humidity due to closer positioning to the sea cost, or 3) significantly different vertical movement of the block caused by tectonic forces, which resulted in an uneven exposure of the blocks to the influence of external forces. Verification of hypothesis No 3 can consist of performing statistical analysis of slope angles for the blocks in the area. If statistics for sufficiently large number of blocks chosen for such analysis will show a clear correlation of average P:\oper\ssb\2486714spec.doc-18/12/01 -7slope angle and block's proximity to the sea coast, the corresponding geomorphological hypothesis can be considered as correct. Otherwise, other hypotheses must be considered as dominant and a relevant procedure for verification must be chosen.) verification of the posited geomorphological hypotheses by means of morphometric and statistical analysis, leading to eventual changes in geomorphological hypothesis of the previous step. Grouping the elementary units of analysis into the bigger formations, based on the similar characteristics exhibited through morphometric values and coefficients upon completing statistical analysis of such values and coefficients. When based on such procedure new combinations of elementary blocks, forming blocks of higher rank are uncovered, repeating the step changing the spatial scale of the analysis towards more or less details, subject of application-specific requirements with eventual repeating of algorithmic cycle starting from the step producing preliminary results of the analysis in the form of a map of delineated blocks; analysing other sources of data such as geological maps through integrating such data within corresponding thematic maps of above-mentioned step (a)-vii, to facilitate further verification of the geomorphological hypotheses according to step and producing a verified map of delineated blocks representative of the likely, based on the input data.

The elementary land units to which the methods of the present invention are directed morphotectonic elements of the Earth's crust of various shape and size are believed to be naturally predetermined. This supports forming hypotheses relating scenarios of the interplay of exogenous and endogenous (tectonic) forces. Appropriately framed geomorphologic hypotheses, verified and reiteratively improved through creating a series of morphometric maps can thus reconstruct the likely local subsurface inhomogeneities with a high degree of reliability. Without the need for detailed sequential field investigations, embodiments of the invention offer previously unattainable integrity, elegance and clarity of morphometric analysis.

P:\oper\ssb\2486714spec.doc-18/12/)1 -8- These and other features and advantages of the present invention will be further apparent from the following specification when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates a hypothetical naturally predefined hierarchical structure of the Earth's crust; Figure 2 is a plan view of a hypothetical example of a block's surface borders, where the ranks of blocks are illustrated; Figure 3 is a simplified schematic representation of a hypsometric map of a hypothetical region; Figure 4 shows a hypothetical example of a drainage network map of a region, with an example of delineating the block's borders, based on the map; Figure 5 shows two hypothetical examples of performing contouring of the recognisable tectonic relief: based on the hypsometry of the region; based on contrasting slope angles derived from the elements of a corresponding thematic map of slope angles; and Figure 6 illustrates the application of statistical analysis of the block's morphometric values and coefficients to verify the possible interrelationship of the blocks.

DETAILED DESCRIPTION OF THE PREFERRED

EMBODIMENT

P:perssb\2486714pec.doc- 18112/111 -9- Figure 1 shows a hypothetical naturally predefined hierarchical structure of the Earth's crust. Unlike plate tectonics, which is a paradigm familiar to geoscientists, the suggested method of modelling goes beyond delineation of the earth crust into big plates. The concept of plate tectonics holds that the earth's crust is divided into a mosaic of about eight rigid but shifting plates in which the continents are embedded and drift along as passive entities.

Instead, proposed is the delineation of the Earth's crust into elements with a hierarchical structure (blocks). In accordance with this method of modelling, the elements of the crust three-dimensional blocks of different hierarchical ranks are relatively loose (tectonically) dynamic units. The smallest blocks and their combinations are generally situated closer to the surface. The bigger blocks of higher rank correspondingly have their foundations at deeper levels, ultimately reaching the asthenosphere.

As can be seen from the example in Figure 1, there are three blocks of the highest rank (namely I, II and III) with their foundation reaching astenosphere. Block I includes a structure of smaller units, situated on its top, with two blocks of the lower rank and a structure of yet smaller rank blocks incorporated on the top of them. Other options of how blocks can be positioned correspond to blocks II and III.

Turning now to Figure 2 one can see how the blocks can be organised in plane view. As an example only, one of the biggest blocks (II) is shown to contain a number of blocks of smaller ranks, including blocks II-1, II-2 and II-3 of only one order smaller rank. It is apparent, that the blocks of smallest ranks can theoretically be uncovered when operating only with input maps of adequately high resolution. Using finer scale input maps, in practice, has application-specific limitations.

Figure 3 is a simplified schematic representation of a hypsometric map of a hypothetical region. Modern software packages can be used to produce rather dense coverage of area's hypsometry. It has to evenly cover altitudes of the landscape of particular area. Thus, a metre elevation step was chosen for relatively shallow areas adjacent to sea level, while P:\oper\sb\2486714spec.doc- 18/1 2/01O steep areas would not be represented properly with such step. Consequently, after the 30 m mark, there are correspondingly 50, 100, 200 and 300 metres marks.

Figure 4 shows imaginable example of drainage network of the region, with an example of delineating few blocks' borders, based on such map and certain additional data for performing contouring of the recognisable tectonic relief (as referred to in the step a-iii.

Typical examples of the contouring guidelines are illustrated on Figure As can be seen, borders of a large block No I are assigned to two high order rivers. However, the choice of the river for the left border is governed by particular geomorphologic hypothesis. Another hypothesis would eventually assigned the left border of the block No I to another river, and only verification of such hypothesis may bring a conclusion regarding a reconstruction of this particular block. For example, depending on the characteristics exhibited by blocks 1,2,3 and 4 of smaller rank, with their borders being delineated along the river streams of lower orders, these four blocks can be determined to belong to either block No I or Block No II of a higher rank.

Fig 5 illustrates two imaginable examples of performing contouring of the recognisable tectonic relief: based on hypsometry of the region; based on contrasting slope angles derived from the elements of corresponding thematic map of slope angles. For the case the changeover from the steeper relief to a smoother one can be considered as a sign of changed subsurface structure (for example, as a result of different geological sediments). The consequently drawn line can, with high degree of probability, serve as the block's border line. For the case there is an apparent discrepancy in the slope angles between the adjacent landforms, which gives a reason for delineating the line, tracing this difference as a probable border. Numerous variants of such delineation will be known to a person skilled in the art.

Fig. 6 demonstrates applying statistical analysis of the block's morphometric values and coefficients to verify the possible interrelationship of the blocks, maintained by corresponding geomorphological hypothesis. Let us assume that elementary blocks for the analysis with a given zoom factor (corresponding scale of the input maps) have been P:\operssb2486714spec.doc- I8/12A)1 -11delineated. Let us also assume that we are using morphometric coefficient a/b (explained on the drawing as a proportion of the shorter and longer axes of the ellipse, fitted within the block) and some morphometric value, symbolically depicted as different colour of corresponding blocks. Statistical distribution of the value of the coefficient a/b gives a certain bell-shaped distribution on corresponding graph. Considering all the blocks contained within the areas 1, 2 3 drastically differs from the separate distribution for the blocks from either only 1, or only 2, or only 3. It is apparent that blocks from the area 1 have similar morphometric coefficient and are very likely to be "sister" blocks. Indeed, ellipse fitted within their borders would be close to the circle with ratio a/b=l. While for the blocks belonging to areas 2 and 3, a/b ratio is closer to 2. Observed '"jump" of statistically analysed characteristics is used to verify one geomorphologic hypothesis.

Another geomorphologic hypothesis would eventually state that blocks from areas 2 3 belong to the same bigger entity block of a higher rank. However, statistical analysis of a morphometric value symbolically expressed through a different colour, rejects this second geomorphologic hypothesis. Consequently, the separation line must be drawn between the areas 2 and 3. This line with high probability can thus be a border of two blocks (namely 2 3) with a rank higher than that of the elementary blocks under analysis for the given zoom factor.

Claims (4)

1. A method of morphometric analysis of lithospheric component structures within a predetermined area of the Earth's crust, including the steps of: delineating blocks within said component structures based on a plurality of different thematic maps of said predetermined area; grouping said blocks into one or more macroblocks according to a plurality of predetermined morphometric values and coefficients associated with each block by comparing respective ones of said morphometric values and coefficients of each block with ones of said morphometric values and coefficients of at least each adjacent block to determine common morphometric properties of the blocks; iteratively redefining the macroblocks according to statistical analysis of each of the morphometric values and coefficients of all of the blocks within the macroblock.

2. A system for morphometric analysis of lithospheric component structures within a predetermined area of the Earth's crust, including: means for delineating blocks within said component structures based on a plurality of different thematic maps of said predetermined area; means for grouping said blocks into one or more macroblocks according to a plurality of predetermined morphometric values and coefficients associated with each block by comparing respective ones of said morphometric values and coefficients of each block with ones of said morphometric values and coefficients of at least each adjacent block to determine common morphometric properties of the blocks; and means for iteratively redefining the macroblocks according to statistical analysis of each of the morphometric values and coefficients of all of the blocks within the macroblock.

3. A method of delineation of a surface of a portion of the earth's crust into lithospheric component blocks at a predetermined scale by analysis of data concerning said surface, the method including the steps of: P:\operssb\2486714spec.doc-18/12A/ -13- delineating macroblocks of said surface and outlining a likely macroblock structure, including the steps of: i) creating a hypsometric map of said portion; ii) creating a map of lineaments of said portion; iii) performing contouring of the recognisable tectonic relief based on said hypsometric map and said map of lineaments to establish possible macroblock borders; iv) creating a drainage network map for said portion, based on topographic information to indicate surfaced borderlines of possible macroblocks; v) creating a map of slope angles of said surface; vi) creating a map of tectomorphoisohypses, based on said hypsometric map; generating corresponding geomorphological hypotheses of the geometry, positioning, mutual hierarchy and three-dimensional tectonic movement of said macroblocks based on the maps created in step and repeating step to narrow the search space when one or more geomorphological hypotheses do not provide an improved spatial resolution; testing the generated geomorphological hypotheses by means of morphometric and statistical analysis, changing one or more of said geomorphological hypotheses based on identified weaknesses in said one or more geomorphological hypotheses, grouping blocks or macroblocks into larger formations, based on similar characteristics of said blocks or macroblocks exhibited through morphometric values and coefficients upon completing statistical analysis of such values and coefficients, and forming blocks of higher rank and repeating step when new combinations of blocks or macroblocks are indicated by a changed geomorphological hypothesis; changing the spatial scale of the analysis towards more or less detail depending on application-specific requirements and repeating steps to producing preliminary results of the analysis in the form of a map of delineated blocks; analysing other sources of data such as geological maps to facilitate further testing of the geomorphological hypotheses according to step and producing a verified map of delineated blocks representative of the likely PAoper\ssb\2486714spec.doc-18/12/01 -14- location of respective morphotectonic blocks within said portion.

4. The method of claim 1 or 3, wherein the method is executed using a computer. DATED this 18th day of December, 2001 Diana Ivanova Polonska by DAVIES COLLISON CAVE Patent Attorneys for the Applicant