On September 8, 1900, a Category 4 hurricane hit the island of Galveston, off the coast of Texas. Category 4 hurricanes are tropical cyclones with intense winds. At the time, weather forecasting did not exist, nor did satellites that can detect the formation of hurricanes in the world's oceans. The United States had never seen a hurricane of this magnitude before. Many residents of Galveston were surprised by the strength of the storm.
The Great Galveston Hurricane devastated the island city with winds of 130 to 140 miles per hour and a storm surge in excess of 15 feet. When its fury finally abated, at least 8,000 people were dead, 3,600 buildings were destroyed, and damage estimates were greater than $20 million ($700 million in today's dollars). To this day, the 1900 Galveston hurricane remains the deadliest natural disaster in the nation's history.
U.S. Weather Bureau forecasters were aware of the Galveston hurricane as early as August 30. By the time the storm reached a position just northwest of Key West on September 6, forecasters were convinced the storm would continue to track to the northeast. However, once in the Gulf of Mexico, the system began to strengthen and veer westward. It was then on a collision course with the Texas coast. Since wireless ship-to-shore communications were not yet available, there was no way to know just when and where the hurricane would strike.
While the usual signs associated with the approach of a hurricane were still not in evidence, Galveston Weather Station Chief Isaac M. Cline was becoming increasingly suspicious of the weather. On September 7, Cline ordered hurricane warning flags to be flown.
In a special report on the hurricane, published in the Monthly Weather Review, Cline later noted, "A heavy swell from the southeast made its appearance in the Gulf of Mexico during the afternoon of the 7th. The swell continued during the night without diminishing, and the tide rose to an unusual height when it is considered that the wind was from the north and northwest. . ."
Early the next morning, Cline said he harnessed his horse to a cart, drove to the beach, and warned everyone of the impending danger from the storm. He advised them to get to higher ground immediately. At the time, the highest point in the city was only 8.7 feet above sea level.
During the storm, Galveston was inundated with a storm surge of 15.7 feet. Cline and his brother Joseph continued to send updated reports to headquarters until the last of the telegraph lines went down.
Cline reported that winds increased steadily throughout the afternoon, reaching a sustained velocity of 100 miles per hour shortly after 6:00 p.m.—at which time the station's anemometer was blown away. Within another two hours, wind speeds were estimated in excess of 130 miles per hour.
With the wind and debris swirling around them, the citizens of Galveston waded through the rapidly rising floodwaters. They sought protection in the strongest-looking homes and structures they could find. One of these structures was Cline's own house, where his wife, three daughters, brother, and about 50 neighbors took refuge from the maelstrom.
In what has frequently been described as the city's finest hour, the citizens of Galveston displayed exceptional resiliency and determination. They decided to rebuild and, in so doing, achieved a remarkable feat of civil engineering. The two-fold project called for raising the grade of the entire city and building a seawall to help protect it.
Read the following sentence from the passage.

The United States had never seen a hurricane of this magnitude before.

Explain the meaning of the word magnitude. Use details from the passage to support your response.