Hazard Assessment of Mt. Vesuvius

2019

SCHULZ, SKYLAR A

GEO327G

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Introduction:

Mt. Vesuvius is a famous volcano that gained its notoriety by erupting in 79 AD. and destroying Pompeii. I will be creating an assessment map of tephra hazard falls, to discover which cities/villages could be in the way of a fallout and calculate an estimate of populations effected by such an event. The range of a small vs. large tephra fall will be portrayed by a 2D map that is shown later in the report.

Problem Formulation:

Making a lahar flow map didn’t seem reasonable considering lahar flows are typically along a river valley and this region of southern Italy doesn’t have any river valleys and is relatively flat in elevation. I am going to create a multiple ring buffer around Mount Vesuvius with a large and small hazard range, then calculate the geometry of the buffers to assess the number of people affected by large and small tephra fallouts. This project will deal solely with approximate tephra ranges and numbers of people that could be effected by an event of various sizes.

Questions:

What places (cities, villages, airports) would feel the effect of a tephra fallout from a Mt. Vesuvius volcanic event?

How can I incorporate wind as a function in the process of making tephra rings to replicate an actual tephra fallout zone?

Data Collection:

Country outline shape files: https://geo.nyu.edu/catalog/stanford-bg854qz0981

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Places with populations: https://mapcruzin.com/free-italy-arcgis-maps-shapefiles.htm

Roads: https://www.diva-gis.org/datadown

Data Preprocessing:

First, I created a geodatabase to store my feature classes and maintain order in keeping all data files contained. When importing the necessary layer files, compressing and extracting the .zip files is important for getting them in an Arc readable format (Figure 1). Of course, double checking the spatial reference data and coordinate system to make sure they are consistent. After importing the appropriate Italian country outline, roads, and places shapefiles, with GCS WGS 1984 coordinate system, I then had to process and import correct point data for the volcano (Figure 2). This was done through excel and saved in the CSV format where it could be imported into a format easily read by the program. When converting these files into arcmap friendly files, keeping spatial reference and coordinate systems consistent is key.

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Figure 0. Creating a geodatabase

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Figure 1. Properly compressing and extracting .zip file *note pink tab*

Excel was used to import point data for Mount Vesuvius.

Figure 2. Mt. Vesuvius point data

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Data Processing and Analysis:

Creating buffers approximately the size of a realistic tephra fallout was the main procedure for my end result. Creating a buffer allows me to visualize and calculate population effected by the tephra fallout. By selecting the input feature for what you want to buffer around and outputting it into a folder concealed in the correct geodatabase is essential for allowing the program to work. I used the distances of 10 km and 100 km to replicate a small and large tephra fallout. Those distances were taken from lab 11 directions.

Figure 3. Creating Buffer Rings to replicate possible tephra fallout

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Buffers were used as boundaries for the hazard being assessed. Once I create multiple ring buffers, I can identify and symbolize the appropriate places of study.

Figure 4. Map image of buffer rings in south west Italy.

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I used the Select By Attributes Tool (Figure 5) in order to marginalize the cities, villages and towns within the buffer. This will help in labeling appropriate places on the map.

Figure 5. Select by Attribute

In order to label places and features appropriate for the map, I had to create new layers for each selected feature (Figure 6.). My ‘places’ feature class would label every town, city, village, airport in Italy when the goal is to solely label the cities and airports effected by the approximate tephra range, so I would use the

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selection tool to select a single type of place and convert that into its own layer. And continue this method for the rest of the places.

Figure 6. Creating Layers from Selected Features

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Results of the multiple buffers are seen in figures 7 and 8 below.

Map 1.

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Map 2.

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Conclusion:

Arcmap is a handy tool in assessing hazard like situations such as this one. By being able to construct a simple 2D map and import appropriate to-date data, I was able to identify towns, cities and the lone airport at risk of this natural disaster. This project resulted in a population of 1,383,152 people feeling the effect of a large tephra fallout and 579,490 people feeling the effect of a small tephra fallout, assuming there were no evacuation warnings and a sudden tephra fallout occured. One of my questions in that I was unsuccessful in answering was about how integrating wind direction and speed into creating this map would affect the tephra fallout zone. If I was able to incorporate wind data, this would be a much more accurate assessment of tephra fallout risks.