ISSN:
1573-0581
Keywords:
real-time observation network
;
ocean-bottom-seismometer
;
velocity seismometer
;
accelerometer
;
tsunami sensor
;
pressure data
;
tsunami record
;
P- and S-waves
;
hypocenter determination
;
Sagami trough
;
subduction zone
;
Tokyo metropolitan area
;
Philippine sea plate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract We installed a real-time operating regional observation network of Ocean-Bottom-Seismometers, connected to an electro-optical fiber communication cable, at the Sagami trough subduction zone, just south of the Tokyo metropolitan area, central Japan. The network, called ETMC, has six seismic observation sites at approximately 20 km spacing. In addition, there are three tsunami observation sites along the ETMC network to monitor the propagation process of tsunamis around the Sagami trough region. The on-line data from the ETMC has been improving the detection capability of smaller-magnitude earthquakes even at areas close to the margin of the trough. The ETMC data analyzing system, which has a function of real-time digital filtering for each seismic channel, can read the arrival times of P- and S-waves precisely, constraining well the automatic on-line hypocenter locations. The network has been providing useful information regarding the bending and downgoing process of the Philippine sea plate at the Sagami trough subduction zone. The pressure sensors of the installed network have a detection capability of tsunami wave trains with an amplitude of less than 1 cm. For example, the sensors recorded the full time history of tsunami wave trains, with mm order resolution, originating from a ‘tsunami earthquake’ with 5.7 MW and the tsunami magnitude of 7.5 occurred near Tori Shima (Tori Is.) of the Izu-Bonin Is. arc on September 4, 1996. The maximum amplitude of the tsunami signals on the trough-floor was approximately 1 cm (P-P), in contrast with approximately 20 cm (0-P) at a coastal site on Izu-Oshima, near the trough. Also, the pressure sensors observed tsunamis due to a large tsunami earthquake (7.1 MW) at the northern New Guinea, on July 17, 1998.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004334021329
