In 30 Days, More Than 4,000 Earthquakes Hit New York City to Los Angeles; USGS Issues New Hazard Map


Over the previous 30 days, more than 4,000 earthquakes have impacted the United States, with hundreds occurring from New York City to Los Angeles and Alaska to Hawaii. While this shaking continues, the USGS has issued an updated seismic hazard map, demonstrating what recent earthquake activity has revealed: significant portions of the country are vulnerable to earthquake damage.

According to the new findings, approximately 75% of the United States may experience potentially devastating earthquakes and strong ground shaking during the next century.

The United States National Seismic Hazard Model (NSHM) was revised in 2023 for all 50 states, including current knowledge on seismicity, fault ruptures, ground movements, and probabilistic approaches to create a standard of practice for public policy and other technical applications. The newly published model data indicates significant modifications as it takes into account more data as well as improved earthquake rupture estimates and ground-motion components.

“In developing the 2023 model, we tried to apply best available or applicable science based on the advice of co-authors, more than 50 reviewers, and hundreds of hazard scientists and end-users, who attended public workshops and provided technical inputs,” the authors of the paper said.

“The hazard assessment incorporates new catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling equations, fault-based structural and deformation models, multi-fault earthquake rupture forecast models, semi-empirical and simulation-based ground-motion models, and site amplification models conditioned on shear-wave velocities of the upper 30 m of soil and deeper sedimentary basin structures.”

A recent study led by the US Geological Survey (USGS) and the Federal Emergency Management Agency (FEMA) predicted that buildings across the US would suffer direct economic losses of $14.7 billion each year due to damage caused by ground shaking. The program authors wrote in the introduction to the new model data, “The USGS National Seismic Hazard Model (NSHM) forms the underlying ground-shaking hazard layer used in this risk assessment.

It is made by developing the nation’s fault and fold deformation databases, interpreting crustal and volcanic seismicity, and evaluating the probabilistic ground-shaking levels for different earthquake sizes, distances, tectonic regimes, and site conditions.” They also said, “The expected number of earthquakes and economic risk in some cities are dangerous to people and the infrastructure there.”

Over the past 50 years, the USGS has continued to improve the NSHM. These models are regularly updated to include new research on earthquake risks in the places they cover. The mainland United States, Hawaii, Alaska, Puerto Rico, and American Samoa have all had new information added.

According to the report for 2023, there is a chance of severe earthquakes everywhere in the US except in the upper midwest, the northern Great Lakes, central and southern Texas, and central and southern Florida. Most of central Alaska, the Big Island of Hawaii, the New Madrid Seismic Zone (NMSZ) around Missouri, Illinois, Kentucky, Tennessee, Mississippi, and Missouri, as well as northwest Wyoming, southern Montana, northeastern Idaho, California, western Nevada, and western Oregon and Washington, are the places where damaging earthquakes are most likely to happen.

Scientists found 500 new flaws in the U.S. that could cause a damaging earthquake as a result of the work they did on this 2023 update.

In the last 200 years, quakes bigger than magnitude 5 have happened in 37 states. This shows that the country has a long history of earthquake activity.

The USGS recently said that both California and Hawaii have a good chance of seeing a damaging earthquake soon, but this model update doesn’t say which one it will be. Scientists say there is a greater than 99% chance that California will have at least one big earthquake in the next 30 years. Scientists in Hawaii say there is a 90% chance that an earthquake will destroy the islands of Hawaii and Maui in less than 100 years.

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