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Shaky Earth Project~The science of phenomena due to earthquakes(2004)

Introduction

Introduction

　In Friendship Outreach Meeting, third year students specializing in science education develop science experimental programme as a part of their courses and give junior high students guidance in them at Miyagi University of Education during summer holidays.

Goal

　It is the goal of this programme to understand the mechanism of earthquakes, phenomena caused by earthquakes especially mechanisms of Tsunami and liquefaction through the experiments. Following the big earthquake in 2003 off Miyagi coast or and another big earthquake highly likely, is one of the immediate disasters for the junior high students in Miyagi. Consequently, the students determined to teach the mechanism of earthquakes and other phenomena to understand more about earthquakes through the experiments.

Programme

　In the morning the mechanism of earthquakes were taught with experiments and observations and in the afternoon the phenomena associated with earthquakes were.

Teaching Plan

Handout worksheet　PDF 696kb

Mechanism of earthquake

Mechanism of earthquakes

　Discussing a familiar earthquake experience related to the generation mechanism of the earthquake for the introduction, and the hypocentre and the epicentre of a structural movement and the earthquake,and other earthquake terms related to the movement in the plate were studied in the morning.

1. Introduction：Motivating from their experiences of the earthquake, the definition of earthquake terms is confirmed, and from the observation of the epicentre distribution in the world, the bias of the hypocentre distribution are demonstrated.
2. The hypocentre distribution and the movement in the plate of the region around Japan: The fact that the hypocentre distribution in the region around Japan correlates to the position of the plate is observed from the observation of the hypocentre distribution according to depth (Figure 1). In addition, the plate is dragged with the reproduction of the movement in the plate device (Figure 2) and movement of plates is observed and modeled.
3. The earthquake by the fault movement: A shallow fault type earthquake such as inland active faults, besides the plate boundary type earthquake, is made to be read from the hypocentre distribution. The model experiment of the fault formation (Figure 3) that observes the cracking by putting the hexahedron agar likened to the earth hardened in the milk carton into an acrylic board without the upper surface and one side and pushing the agar from side is executed, and the photograph of the fault of the Tohoku Institute of Technology Aoba-yama ground is observed.

Figure 1: Left: Hypocentre distribution sheet. The one that Hypocentres of earthquakes that occur in the past ten years around Japan (Science Chronological Table) were plotted on acetate in every 10km from surface of the earth to depth of 100km. Right: A pupil is observing the feature of seismic centre distribution piling up and down the hypocentre distribution sheet in order of depth.

Figure2: Plate motion simulator	Figure3: Fault formation experiment by agar

The science of phenomena due to earthquakes

In the afternoon, it aimed to understand (1) Tsunami and (2) liquefaction especially in phenomenon due to earthquakes through the experiments. Pupils are divided into two groups, and both themes are experienced alternately.

1. Tsunami

　The experiment that simulates the reason Tsunami causes big damage is conducted. The Tsunami tidal wave generation device (Figure 4) is a device that generates the wave by filling the water tank made of acrylic board with water and pushing an acrylic board on the edge of the tank. When the tidal wave surged in the ria type seashore, when damage becomes large, from this case, pupils are told to pay attention to a. the change of the width of water and b. the change of the depth of water. In a, the tidal wave is generated by using the chip in the water tank that width narrows gradually, and the height of the wave at various locations is recorded. In b, depth is changed to three stages, and the spread time of the wave of the distance 1m is measured. The pupils play the role of the person in charge of generation, the person in charge of the measurement, and the person in charge of the record.
It is confirmed that wave rises when width of geographical features narrows, speed quickens when depth is shallow, and big power is necessary for generating wave when depth is deep, so Tsunami is generated by huge power. The model made of the styrene foam that imitates the bay shore in the ria shoreline type geographical features where two above-mentioned effects become visible is set into the water tank and waves are generated. General sea wave that is continuous and short wavelength and how the wave rises ashore are observed and simulated damages by Tsunami.

Figure 4: Appearance of experiment of generation Tsunami	Figure5: Observing Liquefaction

2. Liquefaction

　It aims to understand the conditions under which liquefaction occurs. First of all, the actuality is understood from the damage photograph of liquefaction. Imitating a building on the weak ground by putting a model of a building onto the sand that contains water in a water tank and simulating the moving phenomenon (liquefaction) by generating vibration under the container(Figure 5). In addition, the state of the sand when vibrating is experienced touching by the hand.It makes clear that water, and strong vibration are necessary as the condition that liquidizing occurs from conducting the experiment that changes the volume of water and vibration strength. It is understood through these experiments that liquefaction occurs easily when there is the shake of a strong earthquake in the vicinity of the reclaimed ground along the coast to which ground strength is weak.

Results and Discussion

　The junior high school students had more interest and previous knowledge about earthquakes than they imagined. They helped the progress of the class. It is appreciable enough this time for the students' taking up the earthquake as a theme, devising the experiment handmade, and having made up the class. In the questionnaire that the student executed, most were favourably evaluated in the point of understanding and guidance level.
　The subject of physical geography that starts from the outdoors observation mostly ends learning only by textbooks or experiments in classrooms in the elementary education because of the difficulty of the field observation. At the chance like this time, though the outdoors observation was expected to be taken by all means, the students seemed to think as, "It is necessary to express the event that occurs in too deep place to see by eyes or things that should be observed in the outdoor in a laboratory." , that meant they tended to focus.
　The students took time to decide the theme. In the frame "Physical geography", "The size of the solar system is shown in the playground" experiment was shown from the concept of "Size of the scale" at first, however the theme had to be changed because it didn't progress to a concrete educational content afterwards. It is to be considered in the future also on the teacher side that three months is not enough time for the students who have not done practice teachings to finish making up the experiment class for a whole day.