Man-made Earthquakes Threaten Central and Eastern U.S.

【Unlocking Word Meanings】

　今日の単語・フレーズ

Read the following words/expressions found in today’s article. 

1. frequency [FREE-kwuh n-see] (n.) – the number of times that something occurs during a certain period of time

Example:  The frequency of typhoons increased in the Southeast Asian region in the past five years.

2. magnitude [MAG-ni-tyood] (n.)  – a measure of an earthquake’s intensity or strength

 Example: Many of the town’s buildings collapsed when the earthquake with a magnitude of 8.0 struck last week.

3. contamination [kuh n-tam-uh-NEY-shuh n] (n.) – the state of being dirty or impure

Example: The doctors are investigating the water for possible contamination to avoid health problems.

4. aquifer [AK-wuh-fer] (n.) – an underground layer of rock that holds fresh groundwater

Example: The oil company injects the polluted water under aquifers to avoid contaminating the fresh groundwater.

5. dormant [DAWR-muhnt] (adj.) – presently inactive but may become active again in the future

Example: The volcano remained dormant for two hundred years before it exploded last year.

【Article】

　ニュース記事

Read the text below.

Scientists are convinced that the increase of earthquake occurrence in the central and eastern parts of the U.S. might be man-made. Over the past few years, the frequency of earthquakes in central and eastern U.S. has risen at an alarming rate. During 2010 to 2012, the regions experienced more than 300 earthquakes above magnitude 3.0. This result is a five-fold increase from the period of 1967 to 2000, when the rate was just 21 earthquakes per year. William Ellsworth, a geophysicist from the U.S. Geological Survey, believes that some of these recent earthquakes may have been caused by underground wastewater disposal. Wastewater is water mixed with harmful chemicals and is usually produced during the extraction of oil and gas from underground rocks. To prevent the contamination of fresh groundwater, wastewater is often disposed of by injecting it very deeply into the ground below aquifers. However, these injection wells might probably lead to man-made earthquakes. Ellsworth said that when the wastewater is injected near fault lines, the increased pressure in the fault may cause rock movement that leads to earthquakes. Even faults that have been dormant for millions of years may move under this condition. Ellsworth believes that these findings must be taken seriously and that further regulations on underground wastewater disposal may be necessary to address the risk of man-made earthquakes.

【Viewpoint Discussion】

　ディスカッションテーマ

Enjoy a discussion with your tutor.  

Discussion A

·         Do you think that underground wastewater disposal should be made illegal? Why or why not?

·         In your opinion, how can underground wastewater disposal be minimized? Give examples.

Discussion B

·         What do you think does the increase in the number of natural calamities, earthquakes for example, tell about the environment? Explain.

·         Do you believe that some natural disasters can really be caused by man? Why is that so?

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