Natural Hazards

Ninety-nine percent of the gas molecules emitted during a volcanic eruption are water vapor (H 2 O), carbon dioxide (CO 2 ), and sulfur dioxide (SO 2 ). The remaining one percent is comprised of small amounts of hydrogen sulfide, carbon monoxide, hydrogen chloride, hydrogen fluoride, and other minor gas species. Learn more: Volcanic gases can be harmful to health, vegetation and infrastructure

The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) determines the amount and composition of gases emitted by Kīlauea Volcano. Changes in gas emissions can reveal important clues about the inner workings of a volcano, so they are measured on a regular basis. HVO scientists use both remote and direct sampling techniques to measure compositions and emission rates of gas from Kīlauea...

Landslides are a serious geologic hazard common to almost every State in the United States. As people move into new areas of hilly or mountainous terrain, it is important to understand the nature of their potential exposure to landslide hazards, and how cities, towns, and counties can plan for land-use, engineering of new construction and infrastructure which will reduce the costs of living with...

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material...

No. Even huge amounts of explosive almost never cause even small earthquakes, and it would take hundreds and thousands of small earthquakes to equal a large one, even if it could be done. In addition, we wouldn't have any control over the size of the earthquake being created if it worked, since small and large earthquakes all start out in exactly the same way. It's just not physically possible.

Explosions and earthquakes both release a large amount of energy very quickly, and both can be recorded by seismic instruments. However, because the forces involved in each are very different, the waveforms that each creates look different. Nuclear tests are very near the surface of the earth; all of the energy is released from a small volume surrounding the device. Earthquakes are typically...

On September 10, 1996, the United Nations General Assembly voted 158-3 to approve a treaty prohibiting all nuclear tests. The Comprehensive Test Ban Treaty has been signed by 130 nations - including the United States. President Clinton signed the agreement on September 24, 1996. Seismology is one of several fields which plays a role in monitoring the Comprehensive Test Ban Treaty. Underground...

Solar flares and magnetic storms belong to a set of phenomena known collectively as "space weather". Technological systems and the activities of modern civilization can be affected by changing space-weather conditions. However, it has never been demonstrated that there is a causal relationship between space weather and earthquakes. Indeed, over the course of the Sun's 11-year variable cycle, the...

Kīlauea typically emits between 500 and 14,000 metric tons of sulfur dioxide gas (SO 2 ) per day during periods of sustained eruption. During the 2018 eruption at Kīlauea’s Lower East Rift Zone, SO 2 emissions were over 100,000 metric tons per day, in keeping with the increased vigor of that eruption. Methods for calculating emission rates for SO 2 can be complicated and challenging in the high...

The most critical factors that determine how much vog impacts an area are wind direction and speed. Air temperature, humidity, rainfall, location of the source, and the amount of sulfur dioxide (SO2) being emitted are also factors. During prevailing trade (from northeast) wind conditions, any SO2 emitted from Pu`u `Ō`ō is blown out to sea, while any SO2 from the summit vent often creates vog in Ka...

There is no scientific explanation for the symptoms some people claim to have preceding an earthquake, and more often than not there is no earthquake following the symptoms.

Shallow crevasses can form during earthquake-induced landslides, lateral spreads, or from other types of ground failures, but faults do not open up during an earthquake. An earthquake occurs when two blocks of the earth’s crust slide past one another after having been stuck together in one place for a long time, because of friction on the fault, while the rest of the crust away from the edges has...