Those fields not selected will not be included in the output report. Locating the epicenter and determining the magnitude of an. This volume is placed as a pdf file on the attached handbook cd, under the directory\48. Approximately how long will an swave take to travel from the epicenter of the same. What is the distance of the epicenter from seismic station. Ny29 shows a plot of how the travel times of pwaves and swaves are related to the distance from an earthquake s epicenter. Let t and t i be the origin time of the earthquake and the arrival time at the ith station, respectively. The map shows point x, which is the location of an earthquake epicenter, and point a, which is the location of a seismic station. Tracings made at three separate seismic stations are needed to locate an earthquake epicenter. Curated exercise 11 answers oxford university press. Interactive deep structures in ohio seismic station locations seismic station data seismic magnitudeintensity scales scales comparison chart magnitude scale defined mercalli scale defined what is a digital seismograph. When each point that is that distance away from kansas city is marked, the marks create a circle. A complete list of stations is also available 2 mb is size. The earthquake pwave and swave travel time graph p.
There are hundreds of seismic data recording stations throughout the united states and the rest of the world. How long would it take for the first swave to arrive at seismic station 4,000 kilometers from the epicenter. Iris operates many prominent geophysical facilities. Calculating the epicenter of earthquakes maple programming help. The station book may be searched by station codes, or by defining a search region. Earth science new york regents august 2005 exam base your answers to questions 63 and 64 on the diagram below, which shows two seismogram tracings, at stations a and b, for the same earthquake. Locating and measuring earthquakes putting down roots in. Station book listings international seismological centre. Much of the material in the remaining chapters of this book will deal with. Seismic site effects have been first evidenced during the 1985 mexico city earthquake. When an earthquake occurs, vibrations initiated by fracturing of the earths crust radiate outward from the point of fracture. Nearly 3000 seismic stations distributed worldwide have been systematically. Feb 14, 2010 a seismic station is a laboratory that has equipment that can detect, monitor and record earthquakes locally or anywhere in the world. This graph translates the difference in arrival times of the p waves and s waves into distance from the epicenter to each station.
There is a longer sp lag time at the station closer to the explosion. Base your answers to questions 31 and 32 on the map below. The cartesian coordinates of the true hypocenter and the ith seismic station are x, y, z and x i, y i, z i, respectively. The earthquake creates vibrations in the ground called seismic waves. Epicentral distance is the distance separating the epicenter and the recording seismic station.
For the stations that are less than 800 km in distance to the earthquake, plot the sp times you found in seconds on the sp difference in travel times curve. Why are three seismographs needed at each seismic station. Calculating the epicenter of earthquakes main concept seismology is the study of. What time was it at the station when the earthquake occurred. Scientists have inferred the structure of earths interior mainly by analyzing. Lets say that they know that an earthquakes epicenter is 50 kilometers from kansas city. If we know what those two speeds are, and measure the time interval between the p and s arrivals at the seismic station, we can easily calculate how far the epicenter was from that seismic station. Examine the graph of seismic wave travel times middle graph onthis page.
There are two types of seismic waves associated with every earthquake, called p and s waves. The sumatra earthquake and tsunami december 26, 2004. Determine the distance, in kilometers, from massena to the epicenter of this earthquake. Locating the epicenter of an earthquake introduction. The homogeneous medium gives us simple straightline raypaths to simplify the algebra. Points a, b, and c represent seismic stations on earths surface. The arrival time of the first earthquake pwave at a s a. How long would it take for the first swave to arrive at.
The sequence of problems below will show you how this is done. High school earth sciencemeasuring and predicting earthquakes. The lag time between them is directly related to the distance that the waves travel. Because they each travel with different speeds, seismologists can determine the distance from a seismic station to an epicenter. Using graphs if a seismic station is 2500 kilometers from the earthquakes. Thus, sp lag time can be used to calculated distance to the epicenter of an earthquake. Take a scale and measure the distance 07 mints of 4 mints on yaxis time in minutes from the epicenter by using the figure 6. The arrival times of the pwaves and swaves are indicated on each tracing. What is the distance of the epicenter from the seismic.
According to the earth science reference tables, how long does it take an swave to travel from. Long period seismogram zcomponent showing typical global phases. S wave if the seismic station is kilometers from the earthquake epicenter. Nonlinear acoustic waves in the viscous thermosphere and. The hypothetical seismogram at the top of the page shows how to measure the amplitude.
Find the epicenter of an earthquake polk county school. The question is a bit vague but i will explain as best as i can. International handbook of earthquake and engineering seismology, part a. Base your answers to questions 9 through 11 on the map below, which shows seismograph recording stations at locations a, b, and c. Notice that most of the groundshaking is associated with the surface waves. Base your answer to the following question on the diagram and map below. Approximately how long did it take the pwave to travel to station z. What is the distance between the seattle seismic station.
A seismic station in massena, new york, recorded the. Larger image the southern california seismic network scsn records data from more than 370 seismic stations. What is the difference between the arrival time of the first pwave and the arrival time of the first swave recorded at this station. The first surface wave group arriving at a seismic station at the epicenter. Finding the distance to the epicenter from a seismic station. Determining the earthquake distance you can now determine the distance from each seismic recording station to the earthquakes epicenter using the known times of travel of the s and p waves. The vertical velocity vz of the ground surface motion was measured by. Seismic station x is 800 kilometers from the epicenter. So generally, errors on depth determinations are somewhat greater than on location determinations. Point d represents a location at the boundary between the core and the mantle. They travel in every direction away from the source of an earthquake called the epicenter.
Apr 30, 2010 how long would it take for the first swave to arrive at seismic station 4,000 kilometers from the epicenter. The time it takes for the first s wave to reach the station. Seismic waves from the earthquake are detected at two recording stations. Assuming that swaves travel at 5 kms, it will take 800 s min. Seismic stations detect earthquakes by the tracings made on seismographs. Earth science new york regents august 2002 exam questions. A seismic station 4000 kilometers from the epicenter of an. If a seismic station is 3200 km from an earthquake.
In this case if the epicenter is 3200 km from the seismic station then the swave will take 11 mins 10 sec. In order to locate the epicenter of this earthquake, you need to estimate the time interval between the arrival of the p and s waves the sp interval on the seismograms from three different stations. Wave travel time from the epicenter to the seismic station can be estimated fro the travel charts. Seismograms are a complicated mixture of source radiation effects such as the spectral content and relative amplitude of the p and swave energy that is generated at the source, propagation phenomena such as multiple arrivals produced by reflection and transmission at seismic impedance boundaries or at the surface, and frequency bandlimiting effects of the recording. Figure 2 use the amplitude to derive the magnitude of the earthquake, and the distance from the earthquake to the station. Earth science new york regents august 2002 exam base your answers to questions 43 through 46 on the diagram and map below. Because they each travel with different speeds, seismologists can determine the distance from a seismic station. As an alternative to the search page, the listings page categorises stations by.
Analog seismograms from seismic stations in north america may thus. Approximately how long did it take the pwave to travel to station. Because p and s waves travel at different velocities, the p wave arrives at a seismic station ahead of the s wave. A pwave takes 8 minutes and 20 seconds to travel from the epicenter of an earthquake to a seismic station. If you fill in either the site name or the network affiliation, you may not enter anything in the network code andor station fields. Seismic station z is 1,700 kilometers from the epicenter. Each station records seismic waves from both near and distant earthquakes. Locating the epicenter, determining the magnitude, and. Generally speaking, at increasing distance from the epicenter the wave. The earthquake occurred as the result of thrust faulting on the. Locating the epicenter the source of an earthquake is called the focus, which is an exact location within earth were seismic waves are generated by sudden release of stored elastic energy. What is the time of arrival of an swave for a station that recorded the same event but 6000 km from the epicenter. Distance from the epicenter to the seismic station is. For more information regarding can you solve for the distance of the epicenter from the seismic station given that the sp interval is about 10 minutes, please open this given link.
The location of an earthquakes epicenter point on the earths surface directly above the. How long did it take the first swave to travel 500 kilometers to. Iris staff and subawardees oversee the construction, operation, and maintenance of seismic networks and related data facilities utilized by a wide sector of the earth science community. Approximately how far away from station y is the epicenter.
This book is intended for everyone processing earthquake data, both in the observatory routine and. Identify the information shown on the seismogram that was used to determine that the distance to the epicenter was 500 kilometers. A seismic station 4000 kilometers from the epicenter of an earthquake records the arrival time of the first pwave. Earthquake monitoring in southern california for seventyseven. The distances from each seismic station to the earthquake epicenter have been drawn on the map. The tsunami generated by this quake moved at an average speed of about 600 kilometers per hour. Seismographs are devices that record the earthquakes and do so by showing major waves patterns that is pwaves, swaves and lwaves. The distance of the epicenter of the earthquake from the seismic station is calculated according the difference in arrival time between the two types of seismic waves s waves and p waves. Note the simple transient waveform wavelet of p in the zcomponent of fig. A seismic station is 2,000 kilometers from an earthquake epicenter. Base your answer to the following question on the map below. The earthquake epicenter was located along the pacific coast several hundreds kilometers from mexicocity, the seismic shaking was however extremely strong leading to very large damages figure 2 displays the recordings performed at different distances from the epicenter during the earthquake sequence.
Which recording station is farther away from the epicenter. Approximately how long did it take the pwave to travel to station x. The observed maximum amplitude depends on how far the seismic station is from the epicenter, such that the observed maximum amplitude diminishes with distance from the epicenter. The epicenter is the location where the greatest damage associated with an earthquake occurs. To determine the distance of an earthquake epicenter. This material is discussed in the earthquakes chapter of your textbook. A6 mm 40 sec b9 mm 40 sec c15 mm 00 sec d19 mm 00 sec 14.
A seismic station is a laboratory that has equipment that can detect, monitor and record earthquakes locally or anywhere in the world. This is a set of simulations that demonstrate how seismic waves are used to. What method is used to determine the epicenter of an earthquake. Tutorial on how to find the arrival times of p and s waves from a seismogram for one station to determine distance to the epicenter and origin time of the earthquake also shows how to use page. The distance between an earthquake epicenter and the location of a seismographs can be calculated because. Chapter 2 seismic wave propagation and earth models gfzpublic. The diagram shows three seismograms of the same earthquake recorded at three different seismic stations, x, y, and z. Use the graph you made and the traveltime tool to estimate the distance to the epicenter if the sp lag time is 56. Dec 12, 2017 tutorial on how to find the arrival times of p and s waves from a seismogram for one station to determine distance to the epicenter and origin time of the earthquake also shows how to use page. A coordinate system has been placed on the map to describe locations.
What is the distance between the seattle seismic station and the earthquakes epicenter. Hence, the distance from the earthquake epicenter to the seismic station is 3,000 miles. The epicenter is the point on the surface of earth directly above the focus. All the data are transmitted automatically to caltechusgs in pasadena for processing and distribution of information such as epicenters, magnitudes, and shakemaps. How long did it take the first swave to travel 500 kilometers to reach this seismic station.