Featured Research

from universities, journals, and other organizations

Toward a Better Understanding of Earthquakes

Date:
July 5, 2012
Source:
Karlsruhe Institute of Technology
Summary:
The earth is shaken daily by strong earthquakes recorded by a number of seismic stations worldwide. Tectonic tremor, however, is a new type of seismic signal that seismologist started studying only within the last few years. Tremor is less hazardous than earthquakes and occurs at greater depth. The link between tremor and earthquakes may provide clues about the more destructive earthquakes that occur at shallower depths. Geophysicists have collected seismic data of tectonic tremor in California. These data are now being evaluated in order to better understand this new seismic phenomenon.

Rebecca Harrington, Geophysical Institute, and Peter Duffner, Black Forest Observatory Schiltach, install a seismic station near Cholame, California.
Credit: Werner Scherer, KIT

Earth is shaken daily by strong earthquakes recorded by a number of seismic stations worldwide. Tectonic tremor, however, is a new type of seismic signal that seismologist started studying only within the last few years. Tremor is less hazardous than earthquakes and occurs at greater depth. The link between tremor and earthquakes may provide clues about the more destructive earthquakes that occur at shallower depths. Geophysicists of Karlsruhe Institute of Technology (KIT) collected seismic data of tectonic tremor in California. These data are now being evaluated in order to better understand this new seismic phenomenon.

About a decade ago, researchers discovered a previously unknown seismic signal, now referred to as tectonic tremor. Contrary to earthquakes, tectonic tremor causes relatively weak ground shaking. While tremor may last longer than earthquakes, it does not cause any direct danger. "Both earthquakes and tremor have the same cause. They result from the relative movement on fault surfaces, a result of the motion of the tectonic plates," explains seismologist Dr. Rebecca Harrington, who heads a research group at KIT. "While earthquakes at our research site in California typically occur at depths of up to 15 km below the surface, tectonic tremor signals are generated at depths ranging from approximately 15 to 35 km."

Tectonic tremor was first detected a decade ago in subduction zones in Japan and in the Pacific Northwest in North America. Since then, seismologists have discovered that tremor occurs in many other places, including the San Andreas fault in California. The San Andreas fault marks the boundary where the Pacific Plate and the North American plate drift past each other, generating many earthquakes in the process. KIT researchers have collected new seismic data recording tremor closer to where it occurs than the seismic stations currently installed near Cholame. In mid-2010, KIT researchers, together with scientists of the University of California, Riverside, and the US Geological Survey, Pasadena, installed 13 seismic stations near Cholame, located approximately halfway between San Francisco and Los Angeles. Each seismic station was equipped with a broadband seismometer in a thermally insulated hole in the ground, a small computer, and a solar panel for power. Broadband seismometers are extremely sensitive to small ground motions, are therefore ideal for detecting tremor and small earthquakes. The data recorded over a period of 14 months are presently being analyzed at KIT.

Tectonic tremor signals have a unique character that differs from earthquakes, making them more difficult to detect using automated techniques. In order to address the detection problem, the KIT researchers first developed a new algorithm for the automatic isolation of tectonic tremor. Using their new technique, they found over 2600 tremor events that are now being studied in detail. "In addition to detecting tremor, we will determine their size or magnitude of the individual events. In order to do so, each of the tremor events must be precisely located," says Rebecca Harrington. Additionally, KIT geophysicists compare the tremor and earthquake recordings in California with earthquake recordings at Mount St. Helens volcano, located in the Cascadia subduction zone, located to north of California, in the US state of Washington. A volcano eruption from 2004-2008 produced a series of earthquakes on newly formed faults, where the scientists of the US Geological Survey collect data that are also made available to Rebecca Harrington.

Seismology is still a long way from being able to predict earthquakes. However, seismologists can better estimate the danger posed by earthquakes by understanding what happens on a fault during a seismic event. According to Rebecca Harrington, research of tectonic tremor may play an important role understanding fault behavior. "We understand very little about what happens on a fault when it ruptures. The tectonic tremor generated on the deep part of a fault may provide clues about the behavior on the more shallow parts of a fault where more damaging earthquakes occur."


Story Source:

The above story is based on materials provided by Karlsruhe Institute of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Karlsruhe Institute of Technology. "Toward a Better Understanding of Earthquakes." ScienceDaily. ScienceDaily, 5 July 2012. <www.sciencedaily.com/releases/2012/07/120705133716.htm>.
Karlsruhe Institute of Technology. (2012, July 5). Toward a Better Understanding of Earthquakes. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2012/07/120705133716.htm
Karlsruhe Institute of Technology. "Toward a Better Understanding of Earthquakes." ScienceDaily. www.sciencedaily.com/releases/2012/07/120705133716.htm (accessed July 30, 2014).

Share This




More Earth & Climate News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Climate Change Could Cost Billions According To White House

Climate Change Could Cost Billions According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins