A PROGRAM FOR ROUTINE LOCATION OF T-PHASE SOURCES IN THE PACIFIC

Routine location of T-phase sources in the Pacific

Bulletin of the Seismological Society of America ◽

10.1785/bssa0560010109 ◽

1966 ◽

Vol 56 (1) ◽

pp. 109-118 ◽

Cited By ~ 1

Author(s):

Rockne H. Johnson

Keyword(s):

Peak Power ◽

Power Level ◽

Earthquake Magnitude ◽

Origin Time ◽

Arrival Times ◽

Early Results ◽

The Pacific ◽

Least Squares Fit ◽

The Kuril Islands ◽

T Phase

abstract A program for the routine location of T-phase sources in the Pacific is described. Data for this program are supplied principally by the Pacific Missile Range hydrophone network. Arrival times and power levels are read at Honolulu for processing by an IBM 7040 computer. The solution for location and origin time is the least-squares fit to all hydrophone arrivals which are weighted according to their distribution in azimuth and their distance from the T-phase source. The velocities for the program are obtained from algebraic functions of latitude and longitude which are based upon shot calibrations and upon hydrographic measurements. A T-phase strength is computed from readings of peak power level in a manner analogous to earthquake magnitude. Early results for the r.m.s. difference between T-phase source locations and the corresponding earthquake epicenters were 0.6° in the Aleutians and 1.1° in the Kuril Islands.

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Discussion of “Proposed use of the T phase in tsunami warning systems”*

Bulletin of the Seismological Society of America ◽

10.1785/bssa0410020165 ◽

1951 ◽

Vol 41 (2) ◽

pp. 165-167

Author(s):

L. Don Leet

Keyword(s):

Dominican Republic ◽

Pacific Coast ◽

Sea Water ◽

Tsunami Warning ◽

Columbia University ◽

Warning Systems ◽

The Pacific ◽

Short Period ◽

The Pacific Ocean ◽

T Phase

Abstract Ewing, Tolstoy, and Press of Columbia University reported that “a striking correlation between the occurrence of a short-period earthquake phase (T phase) traveling through the ocean with the speed of sound in sea water and the occurrence of tsunamis has been observed.” Their statements about the characteristics of T are incorrect in every essential detail. For the Pacific Ocean, they list five tsunami between 1933 and 1946, of which the largest, on April 1, 1946, was generated by an earthquake for which no T was recorded. They neglect to mention the earthquake of January 23, 1938, near Hawaii, which produced the largest T recorded on the Pacific coast to date, but no tsunami. The importance of these outstanding exceptions, errors in reporting the data, and uncertainty concerning the actual number of T phases recorded on the Pacific coast combine to make the evidence for any value of T as a tsunami warning decidedly inconclusive. In the Atlantic, the proposal that T be used as a tsunami warning reduces to an absurdity. Ewing, Tolstoy, and Press state that between 1939 and 1948 “20 Dominican Republic shocks produced T phases,” and that one of them was followed by a definite tsunami. Actually, more than 200 Dominican Republic shocks produced T within that span of years, and many in other Atlantic regions. With one minor tsunami among 200 to 250 T phases, the correlation is not impressive.

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T-phase radiators in the western Aleutians

Bulletin of the Seismological Society of America ◽

10.1785/bssa0580010001 ◽

1968 ◽

Vol 58 (1) ◽

pp. 1-10

Author(s):

Rockne H. Johnson ◽

Roger A. Norris

Keyword(s):

Large Volume ◽

Main Shock ◽

Source Location ◽

Earthquake Magnitude ◽

The Pacific ◽

Aleutian Arc ◽

Relationship Of ◽

T Phase ◽

The Relationship

abstract The aftershocks of the Rat Islands earthquake of 4 February 1965 provided a large volume of data for processing with a T-phase source location program. Although the earthquake epicenters were somewhat uniformly distributed through the Rat and Near Islands region, the computed T-phase sources were grouped in six clusters along the Aleutian arc. The clusters are considered to represent radiation from distinct sites along the Aleutian Ridge. These sites are probably submarine promontories which, due to their exposure, radiate energy over broader arcs of the Pacific than do intervening regions. The relationship of T-phase strength to earthquake magnitude varied little among these radiators; however, T phases from sources south of the Aleutian trench were significantly weaker. Identification of the arrivals from separate radiators in the signal from the main shock allowed an estimation of the length and velocity of the faulting. The estimate was 500 km and 3.5 km/sec.

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The Philological Association of The Pacific Coast

PMLA ◽

10.1017/s0030812900130597 ◽

1935 ◽

Vol 50 (4) ◽

pp. 1373-1374

Keyword(s):

Annual Meeting ◽

Pacific Coast ◽

Stanford University ◽

The Pacific

The thirty-seventh annual meeting of the Philological Association of the Pacific Coast was held at Stanford University, California, on November 29 and 30, 1935.

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A scanning electron microscopic study of the veliger larvae of the scallop argopecten purpuratus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103486 ◽

1988 ◽

Vol 46 ◽

pp. 284-285

Author(s):

G.C. Bellolio ◽

K.S. Lohrmann ◽

E.M. Dupré

Keyword(s):

Morphological Description ◽

Electron Microscopic ◽

Larval Stages ◽

Scanning Electron Microscopic Study ◽

The Pacific ◽

Argopecten Purpuratus ◽

Veliger Larvae ◽

20 Nm ◽

Ethanol Series ◽

Scanning Electron

Argopecten purpuratus is a scallop distributed in the Pacific coast of Chile and Peru. Although this species is mass cultured in both countries there is no morphological description available of the development of this bivalve except for few characterizations of some larval stages described for culture purposes. In this work veliger larvae (app. 140 pm length) were examined by the scanning electron microscope (SEM) in order to study some aspects of the organogenesis of this species.Veliger larvae were obtained from hatchery cultures, relaxed with a solution of MgCl2 and killed by slow addition of 21 glutaraldehyde (GA) in seawater (SW). They were fixed in 2% GA in calcium free artificial SW (pH 8.3), rinsed 3 times in calcium free SW, and dehydrated in a graded ethanol series. The larvae were critical point dried and mounted on double scotch tape (DST). To permit internal view, some valves were removed by slightly pressing and lifting the tip of a cactus spine wrapped with DST, The samples were coated with 20 nm gold and examined with a JEOL JSM T-300 operated at 15 KV.

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