This layer allows you to view all recorded earthquakes worldwide for up to the past month. Severity is indicated by color and size of the icon.

Very Small Gray/Blue Icon- < Mag.1.0

Small Green Icon– Mag. 1.1 – 2.4

Medium Yellow/Orange Icon – Mag. 2.5 – 4.4

Large Red Icon – Mag. 4.5-9.0


            Severity — Select the minimum magnitude of displayed earthquakes

            Recency — Choose whether you’d like to see earthquakes from the last hour, day, week, or month.

Earthquake Definitions

Alert – Indicated by corresponding icon color. “Green”, “Yellow”, “Orange”, and “Red”.

Gap – The largest azimuthal gap between azimuthally adjacent stations (in degrees). In general, the smaller this number, the more reliable is the calculated horizontal position of the earthquake. Earthquake locations in which the azimuthal gap exceeds 180 degrees typically have large location and depth uncertainties.

Depth – The depth where the earthquake rupture begins. This depth may be relative to average sea level or the average elevation of the seismic stations which provided arrival-time data for the earthquake location. The choice of reference depth is dependent on the method used to locate the earthquake. Sometimes when depth is poorly constrained by available seismic data, the location program will set the depth at a fixed value. For example, 33 km is often used as a default depth for earthquakes determined to be shallow, but whose depth is not satisfactorily determined by the data, whereas default depths of 5 or 10 km are often used in mid-continental areas and on mid-ocean ridges since earthquakes in these areas are usually shallower than 33 km.

RMS – The root-mean-square (RMS) travel time residual, in seconds, using all weights. This parameter provides a measure of the fit of the observed arrival times to the predicted arrival times for this location. Smaller numbers reflect a better fit of the data. The value is dependent on the accuracy of the velocity model used to compute the earthquake location, the quality weights assigned to the arrival time data, and the procedure used to locate the earthquake.

SIG - A number describing how significant the event is. Larger numbers indicate a more significant event. This value is determined on several factors, including: magnitude, maximum MMI, felt reports, and estimated impact.


Note: You can turn these layers on and off at your discretion by using the toggle switch.