Publications

This is the fourth in a series of six reports that the U.S. Geological Survey published on the results of a comprehensive geologic study that began, as a reconnaissance survey, within 24 hours after the March 27, 1964, Magnitude 9.2 Great Alaska Earthquake and extended, as detailed investigations, through several field seasons. The 1964 Great Alaska earthquake was the largest earthquake...

Kodiak Island and the nearby islands constitute a mountainous landmass with an aggregate area of 4,900 square miles that lies at the western border of the Gulf of Alaska and from 20 to 40 miles off the Alaskan mainland. Igneous and metamorphic rocks underlie most of the area except for a narrow belt of moderately to poorly indurated rocks bordering the Gulf of Alaska coast and local...

The earthquake of March 27, 1964, greatly affected the hydrology of Alaska and many other parts of the world. Its far-reaching effects were recorded as water-level fluctuations in gages operated on water wells and streams. The close-in effects were even more striking, however; sediment-laden ground water erupted at the surface, and even ice-covered lakes and streams responded by seiching...

One of the greatest geotectonic events of our time occurred in southern Alaska late in the afternoon of March 27, 1964. Beneath a leaden sky, the chill of evening was just settling over the Alaskan countryside. Light snow was falling on some communities. It was Good Friday, schools were closed, and the business day was ending. Suddenly without warning half of Alaska was rocked and jarred...

The lack of information on mantle velocities and crustal structure of the U.S.S.R. has led to a preliminary examination of published Soviet earthquake bulletins in the hope of deriving useful velocity and structure information from the data they contain. Mantle velocities deduced from earthquake data on several Russian earthquakes are in excellent agreement with results of Soviet deep...

Several mathematical models were investigated to determine the capa-bilities of the magneto-telluric method for determining the resistivity structure of the earth's crust. The model parameters were based on the crust model proposed by Keller (1963). The mathematical technique used was developed by Cagniard (1953). The investigations indicate that a three-layer model approximation of the...

Whittier, Alaska, lying at the western end of Passage Canal, is an ocean terminal of The Alaska Railroad. The earthquake that shook south-central Alaska at 5:36 p.m. (Alaska Standard Time) on March 27, 1964, took the lives of 13 persons and caused more than $5 million worth of damage to Government and private property at Whittier. Seismic motion lasted only 2½-3 minutes, but when it...

Anchorage, Alaska’s largest city, is about 80 miles west-northwest of the epicenter of the March 27 earthquake. Because of its size, Anchorage bore the brunt of property damage from the quake; it sustained greater losses than all the rest of Alaska combined. Damage was caused by direct seismic vibration, by ground cracks, and by landslides. Direct seismic vibration affected chiefly...

Seismic-refraction measurements from nuclear and chemical explosions were made along a line from the Nevada Test Site (NTS) to Ludlow, California, and additional recordings from nuclear explosions were made southward toward Calexico, California. The time of first arrivals from the Ludlow shotpoint is expressed as T0 = 0.00 + Δ/2.50 (assumed), T1 = 1.00 + Δ6.10, T2 = 2.81 + Δ/6.80, and T3...

The U.S. Geological Survey complete d a seismic-refraction survey in the vicinity of the Tonto Forest Seismological Observatory (T.F.S.O.) in April and May 1964. More than 1200 km of reversed profiles were surveyed to determine the crustal structure and crustal and upper mantle velocities in this area. The purpose of this work was to provide information on wave-propagation paths of...

Interpretation of a reversed seismic-refraction profile between Lake Mead, Nevada, and Mono Lake, California, indicates velocities of 6.15 km/sec for the upper layer of the crust, 7.10 km/sec for an intermediate layer, and 7.80 km/sec for the uppermost mantle. Phases interpreted to be reflections from the top of the intermediate layer and the Mohorovicic discontinuity were used with the...

Precise epicentral location of a seismic event is made difficult by variations in regional traveltimes. A discussion is presented on delays to be expected in the various segments of a generalized travel path of seismic waves. Traveltime variations caused by changes in crustal structure and velocity introduce a major part of the uncertainty in traveltime at both the seismic source and...