Why was the World-Wide Standardized seismic Network Built in the 1960s?
The World-Wide Standardized Seismograph Network (WWSSN) – originally the World-Wide Network of Seismograph Stations (WWNSS) – was a global network of about 120 seismograph stations built in the 1960s that generated an unprecedented collection of high quality seismic data. The WWSSN arose from a political concern.
How many seismic stations exist worldwide?
Formed in partnership among the USGS, the National Science Foundation (NSF) and the Incorporated Research Institutions for Seismology (IRIS), the GSN provides near-uniform, worldwide monitoring of the Earth, with over 150 modern seismic stations distributed globally.
Where are seismographs located?
A seismograph is an instrument for measuring earthquake (seismic) waves. They are held in a very solid position, either on the bedrock or on a concrete base.
What was discovered by the Global seismic Network?
mantle and core, including the discovery of the fine structure in the inner core, maps of mantle strain that reveal details of mantle deformation, observations of “slow earth- quakes,” some of which may be ice quakes associated with movement of glaciers, and insight on the processes that govern how earthquake ruptures …
How many seismograph stations are needed to locate the epicenter of an earthquake?
Seismic stations detect earthquakes by the tracings made on seismographs. Tracings made at three separate seismic stations are needed to locate an earthquake epicenter. Objective: To identify the location of an earthquake epicenter using a travel time graph and three seismograph tracings.
Which wave causes the most damage P or S?
S waves are more dangerous than P waves because they have greater amplitude and produce vertical and horizontal motion of the ground surface. The slowest waves, surface waves, arrive last. They travel only along the surface of the Earth. There are two types of surface waves: Love and Rayleigh waves.
How strong is a 5.5 magnitude earthquake?
Earthquake Magnitude Scale
|5.5 to 6.0||Slight damage to buildings and other structures.|
|6.1 to 6.9||May cause a lot of damage in very populated areas.|
|7.0 to 7.9||Major earthquake. Serious damage.|
|8.0 or greater||Great earthquake. Can totally destroy communities near the epicenter.|
How many seismometers are needed to locate an earthquake?
Triangulation is required to determine exactly where it happened. Three seismographs are needed. A circle is drawn from each of the three different seismograph locations, where the radius of each circle is equal to the distance from that station to the epicenter.
What are the three types of seismographs?
To overcome this problem, modern seismograph stations have three separate instruments to record horizontal waves – (1) one to record the north-south waves, (2) another to record east-west waves, and (3) a vertical one in which a weight resting on a spring tends to stand still and record vertical ground motions.
How many seismograph stations are there in the world?
The World-Wide Standardized Seismograph Network (WWSSN) – originally the World-Wide Network of Seismograph Stations (WWNSS) – was a global network of about 120 seismograph stations built in the 1960s that generated an unprecedented collection of high quality seismic data.
Which is the first community instrument for Global Seismology?
Foreword A good case can be made that the World-Wide Standardized Seismograph Network (WWSSN) was the first community instrument that enabled Global Seismology to become a quantitative, predictive science.
Where can I see a seismogram from an earthquake?
Seismograms from WWSSN stations in the western United States figured very prominently in my first experience with seismological research as a new graduate student. Many of those images are personal icons of how body and surface waves from large earthquakes should be viewed.
Are there any seismic stations in the USSR?
A similar system, the Unified System of Seismic Stations (ESSN, transliterated from Russian), was built in the USSR with 168 stations using Kirnos seismographs. Limited Test Ban Treaty of 1963. The VELA Program.