After a magnitude 7.0 earthquake shook areas near Humboldt County on Wednesday morning and sparked tsunami fears, residents are being reminded again not to be “caught off guard” by these earthquakes by staying alert and alert with earthquake warning systems stay up to date.

California is using science, advanced ground motion monitoring, and new and existing alerting methods to send alerts to residents’ cell phones before the strongest shaking occurs.

“Seconds to dozens of seconds of alarm can provide an opportunity to take life-saving measures such as dropping, covering and restraining, and placing devices into various forms of safe mode,” according to the state’s Earthquake Warning California website.

How quickly someone is alerted depends on how close they are to the origin of the earthquake. The closer someone is to the origin, the faster they will receive the notification.

Officials said there are cases where people may not be warned until the tremors have begun or have passed.

Types of earthquake warnings

California uses the MyShake app, Android earthquake alerts and wireless emergency alerts to send alerts to residents.

Once you get the warning or feel a tremor, that’s your cue to drop, hide and hold on.

How they work

Wireless Emergency Alerts (WEAs): A nationwide system that sends text-like messages to phones during emergencies or imminent danger to life. These types of warnings can be sent by state and local security officials, the National Weather Service and the president.

WEA alerts are used in response to a quake of magnitude 5.0 or greater and are sent to people experiencing mild tremors or greater.

MyShake app

MyShake app: The warning system sends a notification to mobile phones that shaking is occurring. Using ground motion sensors, the system detects earthquakes that have already begun and estimates their size, location and impact. When significant strength is detected, the system issues a ShakeAlert message, providing a warning before the shaking begins.

MyShake alerts are used in response to earthquakes of magnitude 4.5 or greater and are sent to people where the shaking is weak or stronger.

You can download the mobile app for free from the App Store and Google Play.

Android notifications

Android Notification: Google has partnered with the California Governor’s Office of Emergency Services (Cal OES) and the United States Geological Survey (USGS) to send earthquake alerts directly to Android devices in California.

Early warning technology is automatically built into the phones of millions of Android users.

The alerts delivered through the system are based on the ShakeAlert program operated by Cal OES and USGS, which analyzes data from seismic networks across the state, calculates preliminary magnitudes and then estimates which areas will experience shaking.

Note that the Android notification system uses your phone’s general location to determine who receives notifications. Therefore, it is important to enable location services.

Warnings are used in response to a magnitude 4.5 quake and are sent to people who feel only weak or stronger tremors.

For more information, Californians can click here.

KTVU’s O. Gloria Okorie contributed to this report.