I met a gentleman via email, Matt, that has a number of older = seismometers for sale, with some on EBay, a Kinemetrics vertical and = horizontal and a ranger. One of the item numbers is 110369876034, that = listing will take you to the other two he has. He also would like help = in identifying a number of other seismometers he has that he has not = listed as yet. The URL for the pictures is = http://s271.photobucket.com/albums/jj139/shostang/Seismology/ He would = really appreciate list members help in identifying the units he has. ----- Original Message -----=20 From: Bob Hancock=20 To: psn-l@................. Sent: Monday, March 30, 2009 11:58 AM Subject: Re: Rayleigh and Love waves Hi Martin - With two horizontal channels, you an use the amplitude of the P wave = arrivals to determine a great circle path through your station. However = that is insufficient information for you to determine which of two = inbound headings the signal came from. For that information, you need = the initial motion on the P waves from both horizontal channels and the = vertical channel. =20 Bob Hancock On Mar 30, 2009, at 1:53 AM, Tangazazen@....... wrote: Hi Bob, I was most interested in your surface wave comments.Here in = England local earth quakes are rare so most events detected are = teleseismic. I have a pendulum seismometer that resolves both X and Y axis = components independently ( broadband 50 seconds ). If I plot the N-S = verses E-W components during the first few minutes of a teleseismic = event one gets a form that indicates the direction of arrival. The = Svalbard event you mention shows a form whose major axis is along the = NNW-SSE, consistent with it's location relative to England. For the = recent Tonga event M7.8, the X-Y plot has a majors axis virtually north- = south consistent with the shortest path though China, Siberia and the = north pole. Inspection of the individual seismographs show an initial strong = radial component relative to the transverse as would be expected. The last local event was 2 years ago ( M 4.7 ) so I have to make = the most of teleseismic events! Regards Martin =20I met a gentleman via email, = Matt, that has a=20 number of older seismometers for sale, with some on EBay, a Kinemetrics = vertical=20 and horizontal and a ranger. One of the item numbers is = 110369876034, that=20 listing will take you to the other two he has. He also would like = help in=20 identifying a number of other seismometers he has that he has not listed = as=20 yet. The URL for the pictures is ht= tp://s271.photobucket.com/albums/jj139/shostang/Seismology/ =20 He would really appreciate list members help in identifying the units he = has.=----- Original Message -----From:=20 Bob = Hancock=20Sent: Monday, March 30, 2009 = 11:58=20 AMSubject: Re: Rayleigh and Love=20 wavesHi Martin -With two horizontal channels, you an use the amplitude of the P = wave=20 arrivals to determine a great circle path through your station. = However=20 that is insufficient information for you to determine which of two = inbound=20 headings the signal came from. For that information, you need = the=20 initial motion on the P waves from both horizontal channels and the = vertical=20 channel.Bob Hancock
On Mar 30, 2009, at 1:53 AM, Tangazazen@....... = wrote:
Hi Bob,I was most interested in your surface wave comments.Here = in=20 England local earth quakes are rare so most events detected are=20 teleseismic.I have a pendulum seismometer that resolves both X and Y axis=20 components independently ( broadband 50 seconds ). If I plot = the N-S=20 verses E-W components during the first few minutes of a teleseismic = event=20 one gets a form that indicates the direction of arrival. The = Svalbard event=20 you mention shows a form whose major axis is along = the NNW-SSE,=20 consistent with it's location relative to England. For = the recent=20 Tonga event M7.8, the X-Y plot has a majors axis virtually = north-=20 south consistent with the shortest path though China, Siberia = and the=20 north pole.Inspection of the individual seismographs show an initial = strong radial=20 component relative to the transverse as would be expected.The last local event was 2 years ago ( M 4.7 ) so I have = to make=20 the most of teleseismic events!Regards=20 Martin