William Leith

Evaluation of topographic effects on P and S-waves of explosions at the northern Novaya Zemlya Test Site using 3-D numerical simulations

Using a 3-D finite difference simulation, we calculated the effects of surface topography on the amplitudes and waveforms of seismic waves generated by a hypothetical nuclear explosion at the northern Novaya Zemlya test site (Matochkin Shar). The simulation shows substantial azimuthal variations in the amplitude of the downgoing P waveform at shallow depths beneath the source, caused by variations in the amplitude of pP. However, these azimuthal amplitude variations diminish as the wavefront propagates deeper in the crust. Based on these results, we estimate that the topographic scarp considered here produces a maximum azimuthal variation of ±0.05 magnitude units for mb determined from teleseismic P-waves. The sloping topography causes substantial SH motion for azimuths along the strike of the scarp.

Deep seismic sounding in northern Eurasia

For nearly 40 years, the former Soviet Union has carried out an extensive program of seismic studies of the Earths crust and upper mantle, known as “Deep Seismic Sounding” or DSS [Piwinskii, 1979; Zverev and Kosminskaya, 1980; Egorkin and Pavlenkova, 1981; Egorkin and Chernyshov, 1983; Scheimer and Borg, 1985]. Beginning in 1939–1940 with a series of small-scale seismic experiments near Moscow, DSS profiling has broadened into a national multiinstitutional exploration effort that has completed almost 150,000 km of profiles covering all major geological provinces of northern Eurasia [Ryaboy, 1989].

A Review of Nuclear Testing by the Soviet Union at Novaya Zemlya, 1955–1990

The Novaya Zemlya Test Site was used by the Soviet Union for many different types of nuclear weapons tests and nuclear effects tests. Taking our information principally from numerous books and papers in Russian published from 1988 to 2003, we describe the test site history and facilities, the early underwater tests, the many atmospheric tests from 1957 to 1962, and the underground tests in adits and shafts from 1964 to 1990. Each test often entailed several nuclear explosions fired simultaneously. We describe the largest group underground test (about 4.2 mt on 12 September 1973), which was conducted in a unique combination of horizontal adit and vertical shaft; and comment briefly on radioactive releases, which were substantial for some tests. In many but not all cases, the Soviet Unions nuclear tests at Novaya Zemlya followed similar tests conducted by the United States.

Seismic experiments, nuclear dismantlement go hand in hand in Kazakhstan

Unique seismic experiments involving large chemical explosions at different depths have been conducted in Kazakhstan, thanks to nuclear dismantlement activity there. Collaborative efforts of several bodies have provided this creative, cost-efficient extension of the dismantling work, improving technical monitoring and verification of the Comprehensive Test Ban Treaty (CTBT). For the past several years, the Defense Special Weapons Agency (DSWA) has been closing the nuclear test tunnels and bore-holes at the former Soviet nuclear test site nearSemipalatinsk, eastern Kazakhstan, as part of the Nunn-Lugar Cooperative Threat Reduction (CTR) Program. The existence of this program and the infrastructure that was in place to implement it made it possible to conduct the seismic experiments. As a result, benchmark data have been collected on the variations in seismic signals from explosions at different burial depths.

Geophysical advances triggered by 1964 Great Alaska Earthquake

A little more than 50 years ago, on 27 March 1964, the Great Alaska earthquake and tsunami struck. At moment magnitude 9.2, this earthquake is notable as the largest in U.S. written history and as the second-largest ever recorded by instruments worldwide. But what resonates today are its impacts on the understanding of plate tectonics, tsunami generation, and earthquake history as well as on the development of national programs to reduce risk from earthquakes and tsunamis.

Sakhalin earthquake renews concerns about seismic safety in the former Soviet Union

On May 28,1995, a shallow, Ms = 7.6 earthquake struck the northeastern portion of Sakhalin Island, which lies north of Japan in the western part of the Sea of Okhotsk. Most of the oil town of Neftegorsk (Figure 1) was leveled; of its 3000 inhabitants, as many as 2000 may have died. This earthquake is the worst natural disaster to strike the former Soviet Union since 1988, when an Ms = 6.8 earthquake occurred in a populated region of Armenia, killing more than 25,000. Building damage was reported as far north as Okha, 125 kilometers north of Neftegorsk. Ground shaking ruptured the main oil pipeline in at least twelve places between the epicentral area and Okha, and caused the spillage of oil from a storage tank.

Leveraging geodetic data to reduce losses from earthquakes

Seismic hazard assessments that are based on a variety of data and the best available science, coupled with rapid synthesis of real-time information from continuous monitoring networks to guide post-earthquake response, form a solid foundation for effective earthquake loss reduction. With this in mind, the Earthquake Hazards Program (EHP) of the U.S. Geological Survey (USGS) Natural Hazards Mission Area (NHMA) engages in a variety of undertakings, both established and emergent, in order to provide high quality products that enable stakeholders to take action in advance of and in response to earthquakes. Examples include the National Seismic Hazard Model (NSHM), development of tools for improved situational awareness such as earthquake early warning (EEW) and operational earthquake forecasting (OEF), research about induced seismicity, and new efforts to advance comprehensive subduction zone science and monitoring. Geodetic observations provide unique and complementary information directly relevant to advancing many aspects of these efforts (fig. 1). EHP scientists have long leveraged geodetic data for a range of influential studies, and they continue to develop innovative observation and analysis methods that push the boundaries of the field of geodesy as applied to natural hazards research. Given the ongoing, rapid improvement in availability, variety, and precision of geodetic measurements, considering ways to fully utilize this observational resource for earthquake loss reduction is timely and essential. This report presents strategies, and the underlying scientific rationale, by which the EHP could achieve the following outcomes: 1. The EHP is an authoritative source for the interpretation of geodetic data and its use for earthquake loss reduction throughout the United States and its territories. 2. The USGS consistently provides timely, high quality geodetic data to stakeholders. 3. Significant earthquakes are better characterized by incorporating geodetic data into USGS event response products and by expanded use of geodetic imaging data to assess fault rupture and source parameters. 4. Uncertainties in the NSHM, and in regional earthquake models, are reduced by fully incorporating geodetic data into earthquake probability calculations. 5. Geodetic networks and data are integrated into the operations and earthquake information products of the Advanced National Seismic System (ANSS). 6. Earthquake early warnings are improved by more rapidly assessing ground displacement and the dynamic faulting process for the largest earthquakes using real-time geodetic data.

NEHRP Turns 40

This year, the National Earthquake Hazards Reduction Program (NEHRP) turns 40, four decades since the Earthquake Hazards Reduction Act of 1977 was enacted establishing the Program, spurring numerous federal, state, and community actions to reduce earthquake losses in the U.S.A. and its territories and setting a standard for earthquake loss‐reduction projects internationally. Four agencies are partners in NEHRP: the Federal Emergency Management Agency (FEMA), the National Institute of Standards and Technology (NIST, the lead agency), the National Science Foundation (NSF), and the U.S. Geological Survey (USGS). Remarkably few major earthquakes have occurred since 1977, in terms of economic impact, so the earthquake threat has faded from the memories of most Americans, even as geologists and seismologists have identified and quantified a number of fault systems that pose risks of national economic scale. The genesis of NEHRP has been well covered in previous summaries by Wallace (1996) and Hamilton (2003), each of whom described the earthquakes, the people, and the reports that led to the passage of the 1977 Act. The 1964 Alaska and 1971 San Fernando earthquakes were, of course, seminal events. Several expert panels weighed in, there was great enthusiasm for earthquake prediction, and even the ephemeral Palmdale Bulge contributed. There is no need to repeat those good stories here; instead, I will review what has been accomplished since the Act was passed and what key objectives are yet to be realized. In this space, it will not be possible to cover this topic comprehensively, so indulge me while I survey just a few highlights. First, remarkably few major U.S. earthquakes have occurred since 1977, at least in terms of economic impact. In fact, only three have caused losses greater than

Composite regional catalogs of earthquakes in the former Soviet Union

1 billion: 1989 Loma Prieta,

Building for Earthquakes

10.7 billion; 1994 Northridge,