Southland officials stepped up outreach efforts on earthquake preparedness today in the wake of last week’s major twin temblors in the Mojave Desert, which were Southern California’s two biggest earthquakes in 20 years.

Los Angeles County Supervisor Janice Hahn was joined by seismologist Lucy Jones of Caltech and experts from the county’s Office of Emergency Management at a presentation Sunday in downtown Los Angeles intended to remind local residents how to prepare for the inevitable Big One.

The powerful quake struck about 8:16 p.m. Friday, about 9 miles west- southwest of Searles Valley in southwestern San Bernardino County, and occurred on the same fault that produced a magnitude 6.4 foreshock on Thursday, according to the U.S. Geological Survey.

There were no reports of serious damage in Long Beach or Los Angeles and surrounding cities, but seismologists have said the danger is not over yet, with a high number of aftershocks expected during the week.

On Sunday, officials recommended that in the event of an earthquake that knocks out power, water, natural gas or other essential services, people follow the following three basic steps:

Stock up (buy a supply of the same items you purchase every time you go to the market, such as a case of water, ready-to-eat food, etc.);

Have a conversation with family members about your exact emergency plan so everyone will be on the same page and know what to do;

Stay connected by making sure you have an emergency contact list, and make sure you have a backup battery for your cell phone.

Jones, founder of the Dr. Lucy Jones Center for Science & Society, has said that the twin quakes near Ridgecrest do not increase the chances of a

major quake occurring closer to Los Angeles, but officials know that fact doesn’t assuage the fears of many residents.

“These earthquakes have left us rattled,” Hahn said. “… people are worried, and I don’t know if this press conference today is going to make them more worried or less worried, but we’re hoping that what it does is get them prepared, so they can rest a little easier.”

County residents were also urged to sign up for the #ShakeAlertLA app.

Urban search and rescue teams from the Los Angeles and Los Angeles County fire departments and Orange County Fire Authority were deployed to the Kern County city of Ridgecrest to help authorities there in assessing damage to homes and businesses.

“These veteran LAFD responders are proud emissaries of the people of Los Angeles, and eager to leverage considerable skill in helping the people of Kern County,” said Brian Humphrey of the Los Angeles Fire Department.

Los Angeles County Fire Department’s Urban Search and Rescue Team 136 and Hazardous Materials Team 811 were sent to Ridgecrest Friday night, according to Inspector Brian Stevens.

A heavy rescue apparatus and urban search and rescue support vehicle with six firefighters left Friday night for Ridgecrest, the OCFA said.

Many aftershocks have followed, the majority between magnitudes 3 and 4, with seismologists estimating there have been more than 3,000 earthquakes since July 6.

The USGS estimated a 3% chance of another earthquake of magnitude 7 or greater striking the region within the next week. The chance of a quake of magnitude 6 or higher was estimated at 27%, and it is most likely that as many as two such quakes will occur. The chance of a magnitude 5 or higher quake is 96%, with as many as eight likely to occur, the USGS said.

Seismologists say they anticipate between 240 and 410 quakes of magnitude 3 or higher.

“Prepare yourself for the next week to two weeks, this isn’t going to stop in the near future,” Ridgecrest Police Chief Jed McLaughlin told residents late Friday night.

Only minor injuries, “cuts and bruises,” were reported in Ridgecrest. The city’s water system was intact, but water was out in the small town of Trona in San Bernardino County.

Caltrans reported that all roads near the quake area were open, including State Route 178, which re-opened after emergency temporary repairs.

The earthquake was felt as far away as Las Vegas, forcing stoppage of an NBA Summer League game and at Dodger Stadium, where the Los Angeles Dodgers were facing the San Diego Padres. It was the largest in Southern California since a 7.1 quake in 1999 hit the Hector Mines area of the Mojave Desert.

Cracked buildings and injuries were reported in Kern and San Bernardino counties, ABC7 reported. Up to 50 structures were thought to have been damaged overall.

In Ventura County, Naval Air Weapons Station China Lake was declared not mission-capable, according to a post on the base’s Facebook page, although it remained accessible for mission-essential personnel only.

Gov. Gavin Newsom surveyed quake damage in the Ridgecrest area on Saturday and said he had discussed the situation with President Donald Trump. Newsom has requested a presidential emergency declaration for direct federal assistance to further support emergency response and recovery in impacted communities and activated the Governor’s Office of Emergency Services to its highest level. The state is also coordinating mutual aid to local first responders, Newsom said.

“I have all the confidence in the world that the president will be forthcoming in immediate terms with the federal declaration,” Newsom said during a news conference following his tour. “We don’t agree on everything, but one area where there’s no politics, and we (have) worked extraordinarily well together is on emergency response and recovery, and increasing that emergency preparedness.”