### What is an earthquake?

Earthquakes with magnitude of about 2.0 or less are usually called microearthquakes; they are not commonly felt by people and are generally recorded only on local seismographs. Events with magnitudes of about 4.5 or greater - there are several thousand such shocks annually - are strong enough to be recorded by sensitive seismographs all over the world. Great earthquakes, such as the 1964 Good Friday earthquake in Alaska, have magnitudes of 8.0 or higher. On the average, one earthquake of such size occurs somewhere in the world each year.

Magnitude measures the energy released at the source of the earthquake as determined from measurements on seismographs. An earthquake has one magnitude. The magnitude scale most commonly in use now is called the moment magnitude scale. Moment is a physical quantity proportional to the slip on the fault times the area of the fault surface that slips; it is related to the total energy released in the EQ. The moment magnitude provides an estimate of earthquake size that is valid over the complete range of magnitudes, a characteristic that was lacking in other magnitude scales.

Intensity measures the strength of shaking produced by the earthquake at a certain location. Intensity is determined from effects on people, human structures, and the natural environment. An earthquake can produce shaking of many different intensities. The Modified Mercalli Intensity Scale is used in the US.

### Symbols Used in Excel Formula | The purpose of Symbols in Excel Formula

Following symbols are used in Excel Formula. They will perform different actions in Excel Formulas and Functions. Each of these special characters have used for different purpose in Excel. Symbol Name Description = Equal to Every Excel Formula begins with Equal to symbol (=). Example: = B1+B6 () Parentheses All Arguments of the Excel Functions specified between the Parentheses. Example: =COUNTIF ( B1:B5,5 ) () Parentheses Expressions specified in the Parentheses will be evaluated first. Parentheses changes the order of the evaluation in Excel Formula. Example:   =25+ ( 35*2 ) +5 * Asterisk Wild card operator to to denote all values in a List. Example:   =COUNTIF(B1:B5,” * “) , Comma List of the Arguments of a Function Separated by Comma in Excel Formula. Example:   =COUNTIF(B1:B5 , “>” &C1) & Ampersand Concatenate Operator to connect two strings into one in Excel Formula. Example:   =”Total: “ & SUM(C2:C25) \$ Dollar Makes Cell Reference as Absolute in Excel Formula. Exam

### How to create a Barcode Using PHP Barcode 128 Generator

A barcode is an optical, machine-readable, representation of data, the data usually describes something about the object that carries the barcode.We will use PHP to generate Barcode in this tutorial. In this script, we are using coding which will generate barcodes in barcode format Code 128 . First, we will create index.php which will ask for the user input for which Barcode has to be created PHP Barcode Generator <fieldset><legend>Detail Informations</legend><form action="createbarcode.php" method="post"><b>Enter Your Code </b><input name="barcode" type="text" /><input type="submit" value="Create Barcode" /></form></fieldset> Now we will create createbarcode.php which will call function from Barcode code128 class for creating barcode <? php include('barcode128.php'); // include php barcode 128 class // design our barcode display echo

### How to change a MySQL database’s table prefix

Changing a database table prefix is easy and here’s the simple step-by-step guide! For WordPress installations, it’s essential! How to change a prefix 1. In your text editor, change database_name, old_prefix_ and new_prefix_ to the required values: SET @database = "database_name"; SET @old_prefix = "old_prefix_"; SET @new_prefix = "new_prefix_"; SELECT concat( "RENAME TABLE ", TABLE_NAME, " TO ", replace(TABLE_NAME, @old_prefix, @new_prefix), ';' ) AS "SQL"  FROM information_schema.TABLES WHERE TABLE_SCHEMA = @database; 2. Run the query in cPanel or PHPMyAdmin on your WordPress database 3. The output will be a series of SQL queries that will rename the tables for you 4. Run the output 5. Done!   How to add a prefix    If your database doesn’t have a prefix at all, follow the steps above but use the below query that’s been slightly modified fo