EARTHQUAKE PREDICTION BY USING GIS

Transcription

1 EARTHQUAKE PREDICTION BY USING GIS Prepared by: Mansoor Jehangir -A CRP 514 Term Project- -Submitted to : Dr. Baqer Al-Ramadan-

2 INTRODUCTION Natural hazards and catastrophes are recurring phenomenon which affects one or the other part of the world every now and then. Of all such hazards the most devastating are the earthquakes. Occurrence of earthquakes is very uncertain. It can neither be predicted nor forecast. Causes immense destruction and loss of life.

3 INTRODUCTION What is an earthquake and what causes them to happen? Earthquakes occur from the deformation of outer, brittle portions of "tectonic plates", the earth's outermost layer of crust and upper mantle. Due to the heating and cooling of the rock below these plates, causes the adjacently overlying plates to move, and, under great stresses, deform. The rates of plate movements range from about 2 to 12 centimeters per year. What is plate tectonics? The earth's crust (the outer layer of the planet) is made up of several pieces, called plates. Plate tectonics is the continual slow movement of the tectonic plates. What is a fault? A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other.

4 INTRODUCTION Figure on the left shows the world divided into different tectonic plates and figure on the right describes the three plate boundaries

5 Earthquake Prediction It may never be possible to predict the exact time and location of the earthquake. However, when predicting where the next big earthquake might occur, seismologists look closely at areas where major earthquakes have occurred in the past. There are several different methods used for earthquake prediction: Statistical probability Physical measurements Geochemical observations Observations of animal behavior

6 Earthquake Prediction Statistical Method: By collecting adequate historical data, predictions can be made as where and when might a big earthquake strike. Predictions based on statistical analysis of historical earthquake data can only be given for the long or intermediate time frames. Example: If there have been four magnitude 7.0 or greater earthquakes in an area in a 200 year period, then this frequency is one in 50 years i.e. if the last data used for evaluation was of year 2000, then the prediction for earthquake will be on This term project involves the use of this method to predict a future earthquake activity in Japan.

7 Skills Involved: Navigating through and effectively using a GIS software. Changing map symbology. Manipulating tabular information, including selecting attributes, querying tables and sorting tables. Querying map data. Downloading and formatting data from the Internet for use in GIS. Changing map projections. Creating new information from existing data.

8 First task was to download data from the site. Layers include faults, plate lines, countries and world. View of base map with all features on

9 This task includes downloading data from the internet and exploring it. Data was downloaded from the USGS site, which provides many different kinds of Earthquakes data, involving historical data

10 Editing data: ArcView requires a comma deliminated text file or a dbase file to generate points. It also expects west longitude and south latitude to be negative numbers, with no directional designations (N, S, E, or W). For plotting the Earthquake data, I have used a third party software called ET Geowizard. ET Geowizard: It is a third party software through which data from text files, comma delaminated files, or dbase files can be generated into Arcview format and features like points, lines and polygons can be created. There are many other useful functions available in the software.

11 Labeling and symbolizing features: Colors, fonts, size and positions were assigned to the features so that the map can be viewed without any difficulty. Symbolizing Features: Plate boundary layer was symbolized by categorical attributes, using different colors for different types. Earthquake data layers (points) were also categorically symbolized for making the map more informative. Classifying the earthquake values by magnitude (natural brinks) presents a clear picture on the map, as to which value of the earthquake is larger at any particular location.

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13 Analyzing Data: Eight different earthquake data layers were added. Layers include earthquake data of the year 1997, 2000, 2001, 2002, 2003 and Two other data sets were included to perform historical analyses in the most earthquake prone area of the world, Japan.

14 What do we notice about the distribution of these earthquakes? By examining the map, we can say that most of the earthquakes occur near plate boundaries. By running a query we can also find out the percentage of earthquakes within 100 miles or 200 of the plate boundaries. The result of the query shows that about 87% of the earthquakes strike within the 200 miles of the plate boundary.

15 What type of plate boundary is associated with earthquakes with a magnitude of 6.0 or greater? Using features by attributes and running a query can point us to the plate boundary which is mostly associated with earthquakes having larger magnitude. Therefore the result of the query clearly shows that big earthquakes occur most frequently at convergent plate boundaries.

16 Similar query is performed as before, to find the percentage of earthquakes striking within 100 and 200 miles of convergent boundaries. Results in the table below shows the number of earthquakes occurring within 100 and 200 miles of convergent boundaries. Year Within 200 miles Within 100 miles % 47 % % 63 %

17 Why is Japan, so earthquake prone area? Display units were set to decimal minutes seconds, but for our query, we need to change it to miles, as shown in figure. Next task will be to zoom to Japan. The zoomed frame is captured as a bookmark for future reference.

18 Why is Japan, so earthquake prone area? Query is run by which convergent boundaries and country Japan is selected. The figure clearly shows that Japan lies near most active boundary i.e. Convergent boundaries. Using the measurement tool, we can find the distance from the plate boundary to the closest large earthquake. Display shows the figure of 174 miles, which proves why Japan is most earthquake prone country of the world. Since it is already proved that most EQs occur within 200 miles from the convergent boundary.

19 Next and final task is to predict when the next big earthquake will strike Japan in future. Using the statistical method a query is run to find the occurrence of earthquake (magnitude 6.5 or greater) in the country Japan. This data is from year 1556 till 2003.

20 By the query results shown in the previous slide, the results can be calculated as: Since the data is from year 1556 till 2003, means a ( ) 447 years data. In 447 years, 9 big earthquakes have struck Japan. With a frequency of 1 in 50 years (447 / 9 = 50). Therefore we can say that in the year 2053 ( ), there is a fair chance of big earthquake striking the country Japan again.

21 CONCLUSION Scientists can not predict the exact location, time, or magnitude of an earthquake. But by statistical method we can identify approximate time, as to when it is more likely for a big earthquake to occur sooner rather than late. All the detail analysis of the data clearly shows why Japan is most earthquake prone area of the world, and By statistical method of prediction of earthquake; it is mostly likely that in the year 2053, next big earthquake will strike Japan.

22 THANKYOU Questions & Comments