Natural Hazards

Filter Total Items: 590
Date published: July 11, 2019
Status: Completed

Comparing Shaking Intensity from Two Bay Area Earthquakes

The 1989 Loma Prieta earthquake caused billions of dollars in damage and claimed more than sixty lives. But was it "the big one"? Take a look at the comparison between the images below for the 1989 Loma Prieta and the 1906 San Francisco earthquakes, and decide for yourself.

The colors on the map indicate Modified Mercalli Shaking Intensity (MMI) at each point, which is usually (but not...

Date published: July 1, 2019
Status: Completed

Seismographs - Keeping Track of Earthquakes

Throw a rock into a pond or lake and watch the waves rippling out in all directions from the point of impact. Just as this impact sets waves in motion on a quiet pond, so an earthquake generates seismic waves that radiate out through the Earth.

Date published: June 28, 2019
Status: Active

Seismic Seiches

Definition of seismic seiches and examples dating back to their first public mention in 1755.

Date published: June 28, 2019
Status: Active

Recommended Reading for the Changing Earth

Recommended titles for the Changing Earth for both adults and kids.

Date published: June 28, 2019
Status: Active

Introduction to Paleoseismology

  

Date published: June 28, 2019
Status: Completed

Paleoseismology and the Hayward Fault

A large, widely damaging earthquake will occur on the Hayward fault in the future. That much we know.
What we don't know is when.

Date published: June 27, 2019
Status: Completed

How Seismic Waves Affect Different Size Buildings

  

Date published: June 27, 2019
Status: Completed

Groundwater Effects from Earthquakes

Note: Some of the explanations below are speculative and should not be relied upon for decision-making. Please see the reference articles (below) for published results.

Seismic waves have two main types of effects on groundwater levels: oscillations, and "permanent" offsets. Muddy or turbid water at long distances from...

Date published: June 27, 2019
Status: Completed

Focal Mechanisms... or "Beachballs"

This page explains the concept of focal mechanisms, commonly referred to as "beachballs".

Date published: June 27, 2019
Status: Completed

Earthquake Magnitude, Energy Release, and Shaking Intensity

Earthquake magnitude, energy release, and shaking intensity are all related measurements of an earthquake that are often confused with one another. Their dependencies and relationships can be complicated, and even one of these concepts alone can be confusing.

Here we'll look at each of these, as well as their interconnectedness and dependencies.

Date published: June 26, 2019
Status: Active

Information by Region - Wisconsin