March 11, 2010 in Washington Voices

Recent large earthquakes within normal activity range

Randy Mann

Several students from my physical geography class at North Idaho College asked me about the recent earthquake activity in Haiti, Chile and Turkey. They wanted to know if this was an increase in seismic activity.

According to earthquake experts at the United States Geological Survey, the recent earthquake activity is within normal ranges, but there are three main reasons why we’re seeing more news about the deadly quakes.

The first reason is that the quality of reporting is much higher in recent years. Second, there are now more digital seismic networks around the globe for better reporting and also receiving data in real time. The last reason is that more people live in quake-prone areas now when compared with several decades ago.

The big earthquake in Chile on Feb. 27 measured 8.8 on the Richter scale and slightly altered the Earth’s rotation. Richard Gross, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., calculated last week that the recent Chile earthquake shortened the day’s length by approximately 1.26 microseconds. This microsecond dip is permanent, according to Gross. The very slight decrease in our day’s length was likely due to the shifting of land masses from the big quake.

The length of a solar day is the exact time that it takes for the Earth to complete one rotation, 86,400 seconds or 24 hours. A change of just 1.26 microseconds will have little, if any, effect on the residents of this planet.

Locally, it is looking less promising for snow as we move further along into March. Our best chance to see snow is around the end of this month into early April. It still looks like a cooler and wetter spring season ahead for the Inland Northwest. However, there will be many days with bright sunshine and mild to warm temperatures to enjoy.

The summer of 2010 looks hot and drier than normal. This is good news for golfers and other outdoor enthusiasts. However, the dry weather may present problems for area firefighters.

Reach Randy Mann at randy@longrange

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